0001628280-24-036127 | 10-Q | XBRL Viewer

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License, and Funding Agreements	6 Months Ended
License, and Funding Agreements	Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
License, and Funding Agreements	LICENSE AND FUNDING AGREEMENTS Research and Development Incentive Program The Company participates in a research and development incentive program provided by the Austrian government whereby the Company is entitled to reimbursement by the Austrian government for a percentage of qualifying research and development expenses and capital expenditures incurred by the Company’s subsidiary in Austria. As of June 30, 2024, the amount due under the program is $0.9 million, which amount is included in research and development incentive receivable in the condensed consolidated balance sheet. During each of the six months ended June 30, 2024 and 2023, the Company recorded $0.3 million of income related to the program within the condensed consolidated statements of operations and comprehensive income (loss) as other income. License Agreements In July 2014, the Company entered into a license agreement with Genzyme (the “Genzyme Agreement”) pursuant to which the Company was granted an exclusive license to certain patents and intellectual property owned or controlled by Genzyme related to the CXCR4 receptor to develop and commercialize products containing licensed compounds (including but not limited to mavorixafor) for all therapeutic, prophylactic, and diagnostic uses, with the exception of autologous and allogenic human stem cell therapy. Under the terms of the Genzyme Agreement, the Company is obligated to use commercially reasonable efforts to develop and commercialize licensed products for use in the field in the United States and at least one other major market country. The Company has the right to grant sublicenses of the licensed rights that cover mavorixafor to third parties. As of June 30, 2024, the Company is obligated to make future milestone payments in the aggregate amount of up to $13.0 million, contingent upon the achievement by the Company of certain clinical-stage regulatory and sales milestones with respect to licensed products. During the three months ended June 30, 2024, a $7.0 million regulatory milestone was made after receipt of FDA approval of the Company’s NDA on April 26, 2024. The payment was recorded as a definite-lived intangible asset as discussed in Note 8. The remaining regulatory milestones include (i) $3.0 million for the acceptance by the European Medicines Agency (“EMA”) of the Company’s first drug application and (ii) $5.0 million upon the notification by the EMA of regulatory approval of the Company’s first drug application. The Company must also make one-time sales milestone payments of $0.5 million, $1.5 million, and $3.0 million on cumulative net sales of $50.0 million, $150.0 million, and $300.0 million, respectively. The Company has accrued $3.0 million of regulatory milestones and $0.5 million of sales-based milestones as a component of the definite-lived intangible asset, as management has concluded that the achievement of these milestones is probable. The Company is also obligated to pay Genzyme tiered royalties based on net sales of licensed products that the Company commercializes under the agreement. Upon the first sale of the Company’s drug product in the U.S., the Company will incur a royalty on annual net sales at a rate of 6% up to $150 million, 10% on the portion of annual net sales between $150 million and $300 million, and 12% thereafter on annual sale over $300 million. The Company includes these royalties in cost of revenue. There were no material modifications of the Company’s license or research and development incentive agreements during the six months ended June 30, 2024.

Commitment and Contingencies	6 Months Ended
Commitment and Contingencies	Jun. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitment and Contingencies	COMMITMENTS AND CONTINGENCIES The Company has agreements with clinical research organizations (“CROs”) pursuant to which the Company and the CROs are conducting clinical trials. The Company may terminate these agreements by providing notice pursuant to the contractual provisions of such agreements and would incur early termination fees. The Company has agreements with contract manufacturing organizations (“CMOs”) for the production of mavorixafor for use in clinical trials. The Company’s agreement with the CMO who produces batches of drug substance for use in the Company’s clinical and commercial drug supply contains cancellation provisions that would require the Company to pay up to the full contract value upon cancellation. As of June 30, 2024, the Company has approximately $2.7 million of such commitments in place subject to cancellation provisions. Indemnification Agreements— In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and its executive officers that will require the Company to, among other things, indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnification obligations. The Company is not currently aware of any indemnification claims and has not accrued any liabilities related to such obligations in its condensed consolidated financial statements as of June 30, 2024 or December 31, 2023. Legal Proceedings— The Company is not a party to any litigation and does not have contingency reserves established for any litigation liabilities. At each reporting date, the Company evaluates whether or not a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of the authoritative guidance that addresses accounting for contingencies. The Company expenses as incurred the costs related to any legal proceedings.

Long Term Debt - Hercules Loan Agreement - Additional Information (Detail) - USD ($)		3 Months Ended	6 Months Ended	30 Months Ended
	Jul. 01, 2024	Jun. 30, 2024	Jun. 30, 2024	Mar. 31, 2021
Hercules Loan Agreement
Debt Instrument [Line Items]
Proceeds from lines of credit				$ 75,000,000.0
Debt instrument variable percentage		10.15%
Interest rate increase percentage		4.00%
Effective interest rate of loan		12.60%	12.60%
Principal payments			$ 0
Maximum term loan borrowing capacity		$ 115,000,000.0	115,000,000.0
Hercules Loan Agreement \| Share-Based Payment Arrangement, Tranche One
Debt Instrument [Line Items]
Maximum term loan borrowing capacity		32,500,000	32,500,000
Hercules Loan Agreement \| Share-Based Payment Arrangement, Tranche Two
Debt Instrument [Line Items]
Maximum term loan borrowing capacity		20,000,000.0	20,000,000.0
Hercules Loan Agreement \| Share-Based Payment Arrangement, Tranche Three
Debt Instrument [Line Items]
Maximum term loan borrowing capacity		7,500,000	$ 7,500,000
Hercules Loan Agreement \| Forecast [Member]
Debt Instrument [Line Items]
Line of credit facility periodic payment	$ 2,800,000
Hercules Loan Agreement \| Prime Rate
Debt Instrument [Line Items]
Debt instrument variable percentage			3.15%
Hercules Second Amended Loan Agreement \| Min Cash Test Date 1
Debt Instrument [Line Items]
Line of Credit, Covenant, Minimum Cash		$ 20,000,000	$ 20,000,000

Summary of Significant Accounting Policies - Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Cash and cash equivalents	$ 147,218	$ 99,216
Restricted cash, current (included within prepaid expenses and other current assets)	0	250
Restricted cash, non-current	778	782
Total cash, cash equivalents and restricted cash	$ 147,996	$ 100,248	$ 137,456	$ 123,028

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 147,218	$ 99,216
Marketable securities	21,536	15,000
Research and development incentive receivable	854	562
Inventory	831	0
Prepaid expenses and other current assets	4,977	7,298
Total current assets	175,416	122,076
Property and equipment, net	808	745
Goodwill	17,351	17,351
Finite-Lived Intangible Assets, Net	10,375	0
Right-of-use assets	4,872	5,650
Other assets	1,789	1,436
Total assets	210,611	147,258
Current liabilities:
Accounts payable	7,986	8,947
Accrued expenses (Note 9)	19,744	12,816
Current portion of lease liability	1,172	1,099
Total current liabilities	28,902	22,862
Long-term debt, including accretion, net of discount	75,030	54,570
Lease liabilities	2,026	2,612
Warrant liability (Note 5)	9,223	15,683
Other liabilities	979	432
Total liabilities	116,160	96,159
Commitments and contingencies (Note 12)
Stockholders’ equity:
Common stock, $0.001 par value, 500,000,000 shares authorized as of June 30, 2024 and December 31, 2023, respectively; 168,196,180 and 167,434,595 shares issued and outstanding as of June 30, 2024 and December 31, 2023, respectively	168	167
Additional paid-in capital	533,280	528,956
Accumulated other comprehensive loss	(159)	(119)
Accumulated deficit	(438,838)	(477,905)
Total stockholders’ equity	94,451	51,099
Total liabilities and stockholders’ equity	$ 210,611	$ 147,258

Net Loss per Share - Additional Information (Detail)	Jun. 30, 2024 $ / shares
Pre Funded Warrant \| Maximum
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Exercise Price (usd per share)	$ 0.01

Leases - Additional Information (Detail) $ in Thousands		6 Months Ended
Leases - Additional Information (Detail) $ in Thousands	Nov. 11, 2019 USD ($)	Jun. 30, 2024 USD ($) m²	Dec. 31, 2023 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease, liability		$ 3,198
Right-of-use assets		$ 4,872	$ 5,650
Vienna Lease
Lessee, Lease, Description [Line Items]
Office space \| m²		1,200
Lease not yet commenced, term of contract		7 years
Annual base rent		$ 282
Allston Lease
Lessee, Lease, Description [Line Items]
Lease not yet commenced	$ 1,100

Stock-Based Compensation

6 Months Ended

Jun. 30, 2024

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

STOCK-BASED COMPENSATION

As of June 30, 2024, there is an aggregate of approximately 2.0 million shares of common stock available for issuance under the Company’s equity incentive plans. Approximately 4.7 million shares of common stock remain available for issuance under the 2017 ESPP.

Stock Option Valuation— The following table presents, on a weighted average basis, the assumptions used in the Black-Scholes option-pricing model to determine the grant-date fair value of stock options granted to employees, directors and non-employees.


	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023		2024		2023
Risk-free interest rate	4.4	%	4.0	%	4.2	%	3.8	%
Expected term (in years)	6.1		6.1		6.1		6.0
Expected volatility	96.5	%	93.4	%	96.0	%	92.1	%
Expected dividend yield	0	%	0	%	0	%	0	%

Stock Options

The following table summarizes the Company’s stock option activity for the six months ended June 30, 2024:


	Number of Shares	Weighted Average Exercise Price		Weighted Average Contractual Term (Years)	Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2023	6,008,541	$	2.97	8.6	$	24
Granted	4,373,875	1.09

Forfeited and Expired	(476,118)	2.12
Outstanding as of June 30, 2024	9,906,298	$	2.18	8.8	$	—
Exercisable as of June 30, 2024	1,813,063	$	6.55	6.2	$	—
Vested and expected to vest as of June 30, 2024	7,672,558	$	2.47	8.6	$	—

The weighted average grant-date fair value per share of stock options granted during the six months ended June 30, 2024 and 2023 was $0.86 and $1.05, respectively.

Restricted Stock Units— The following table summarizes the Company's restricted stock unit activity for the six months ended June 30, 2024:


			Number of Shares
Unvested as of December 31, 2023			3,118,824
Granted			6,242,459
Vested			(829,851)
Forfeited			(313,961)
Unvested as of June 30, 2024			8,217,471

During the six months ended June 30, 2024, the Company granted performance-based restricted stock units (“PRSUs”) to its employees. The PRSUs vest 50% based on the Company’s achievement of each of two operational milestones conditioned on the grantee’s continued employment with the Company. As of June 30, 2024, neither of the two performance criteria had been met. Stock-based compensation expense has been recognized for awards for which vesting is considered probable using the accelerated attribution model based on the fair value of the awards as of the date of grant and management’s best estimate of the date the probable operational milestone will be achieved. The Company updates its estimates related to the probability and timing of achievement of the operational milestones each period until the award either vests or is forfeited.

Stock-Based Compensation— As of June 30, 2024, total unrecognized compensation expense related to unvested stock options and restricted stock units was $8.5 million, which is expected to be recognized over a weighted average period of 2.2 years.

Stock-based compensation expense was classified in the condensed consolidated statements of operations and comprehensive income (loss) as follows:


	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2024		2023		2024		2023
Research and development expense	$	1,182	$	1,120	$	1,965	$	1,951
Selling, general and administrative expense	1,246		1,022		2,202		1,836
Total stock-based compensation	$	2,428	$	2,142	$	4,167	$	3,787

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, weighted average grant date fair value (in usd per share)	$ 1.05	$ 0.86
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost of stock based awards	$ 8,500
Unrecognized compensation cost of stock based awards, recognition period	2 years 2 months 12 days
2019 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance	2,000,000
Two Thousand Seventeen Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance	4,700,000

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Revenue

6 Months Ended

Jun. 30, 2024

Revenue from Contract with Customer [Abstract]

Revenue

PRODUCT REVENUE, NET

During the three and six months ended June 30, 2024, the Company recorded $0.7 million of gross revenue from the sale of its product to its customer. The Company also recorded an estimate of variable consideration as a provision against gross revenue resulting in net revenue of $0.6 million for the three and six months ended June 30, 2024.

The following table summarizes the activity in each of the product reserve accounts for the six months ended June 30, 2024.


(in thousands)	Rebates and Discounts		Co-Pay Assistance		Product Returns		Total
Beginning balance at December 31, 2023	$	—	$	—	$	—	$	—
Provision related to revenue in the three and six month period ended June 30, 2024	44		35		92		171
Credits and payments made during the period	(21)		(20)		—		(41)
Balance as of June 30, 2024	$	23	$	15	$	92	$	130

The provision for contractual discounts provided to the Company’s customer is recorded as a reduction of accounts receivable. The provisions for co-pay assistance payments, contractual rebates and product returns are classified within accrued expenses.

The following table provides a rollforward of accounts receivable for the six months ended June 30, 2024. There was no activity in accounts receivable in the six months ended June 30, 2023.


(in thousands)	Accounts Receivable
Beginning balance at December 31, 2023	$	—
Increase in accounts receivable for drug product sales	713
Decrease in accounts receivable for cash collections	(713)
Balance as of June 30, 2024	$	—

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

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-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-13

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org//606/tableOfContent

+ Details

Net Loss per Share

6 Months Ended

Jun. 30, 2024

Earnings Per Share [Abstract]

Net Loss per Share

NET INCOME (LOSS) PER SHARE

Basic and diluted net income (loss) per share was calculated as follow:


	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands, except share and per share data)	2024		2023		2024		2023
Numerator:


Net income (loss)	$	90,833	$	(55,712)	$	39,067	$	(79,732)
Denominator:
Weighted average shares of common stock outstanding—basic	200,440,473		168,737,764		200,216,035		157,415,524
Net income (loss) per share— basic	$	0.45	$	(0.33)	$	0.20	$	(0.51)
Effective of dilutive securities
Time-based restricted stock units	244,804		—		163,072		—

Employee stock purchase plan	116,034		—		76,776		—
Dilutive potential common shares	360,838		—		239,848		—
Weighted average shares of common stock outstanding—diluted	200,801,311		168,737,764		200,455,883		157,415,524
Net income (loss) per share— diluted	$	0.45	$	(0.33)	$	0.19	$	(0.51)

Basic and diluted weighted average shares of common stock outstanding for the three and six months ended June 30, 2024 and June 30, 2023 include the weighted average effect of outstanding pre-funded warrants for the purchase of shares of common stock for which the remaining unfunded exercise price is $0.01 or less per share. The Company’s potentially dilutive securities include outstanding stock options, unvested restricted stock units and warrants to purchase shares of common stock for the three and six months ended June 30, 2024 and 2023. For the three and six month periods ended June 30, 2023, during which the Company recorded a net loss, all potentially dilutive securities have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share, and thus they are considered “anti-dilutive.” For these periods, the weighted average number of shares of common stock outstanding used to calculate both basic and diluted net loss per share of common stock is the same. For the three and six month ended June 30, 2024, the Company reported net income. For these periods, the dilutive effect of outstanding stock options, restricted stock units and warrants were calculated using the treasury stock method, whereby all such awards were assumed to be exercised at the beginning of the period. The hypothetical proceeds from such exercises, including the average unrecognized stock compensation expense for outstanding stock options and restricted stock units, were assumed to be used to purchase outstanding common stock at the average price during the period. The net share impact of dilutive securities was added to the weighted average basic common shares outstanding to calculate weighted average diluted shares outstanding.

The Company excluded the following potential shares of common stock, presented based on amounts outstanding at each period end, from the computation of diluted net income (loss) per share for the periods indicated because including them would have had an anti-dilutive effect:


	Three Months Ended June 30,		Six Months Ended June 30,
	2024	2023	2024	2023
Options to purchase shares of common stock	9,906,298	3,583,186	9,906,298	3,583,186
Unvested restricted stock units	7,800,805	5,859,232	7,800,805	5,859,232
Warrants to purchase shares of common stock (excluding prefunded warrants, which are included in basic shares outstanding)	76,378,805	80,246,459	76,378,805	80,246,459
	94,085,908	89,688,877	94,085,908	89,688,877

Common Stock Warrants - Summary of Outstanding Warrants to Purchase Shares of Common Stock (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jun. 30, 2024	Dec. 09, 2022	Jul. 06, 2022	Mar. 03, 2022	Nov. 09, 2021	Mar. 23, 2021	Nov. 02, 2020	Nov. 29, 2019
Class of Warrant or Right [Line Items]
Number of Shares of Common Stock Issuable (in shares)	108,792,939
Class Of Warrant Or Right. Aggregate Proceeds From Warrants Issued		$ 7,500	$ 14,500	$ 1,400	$ 10,000	$ 435		$ 21,000
Class of Warrant or Right, Additional Exercise Price of Warrants or Rights			$ 0.001	$ 0.01			$ 0.01	$ 0.001
Funded
Class of Warrant or Right [Line Items]
Exercise Price (usd per share)			$ 1.094	$ 1.79	$ 4.97	$ 8.69		$ 11.999
Issuance On October 25, 2016
Class of Warrant or Right [Line Items]
Exercise Price (usd per share)	$ 19.78
Issuance On October 25, 2016 \| Legacy Warrants
Class of Warrant or Right [Line Items]
Number of Shares of Common Stock Issuable (in shares)	5,155
Issuance On December 28, 2017 One
Class of Warrant or Right [Line Items]
Exercise Price (usd per share)	$ 19.78
Issuance On December 28, 2017 One \| Legacy Warrants
Class of Warrant or Right [Line Items]
Number of Shares of Common Stock Issuable (in shares)	115,916
Issuance On September 12, 2018 One
Class of Warrant or Right [Line Items]
Exercise Price (usd per share)	$ 19.78
Issuance On September 12, 2018 One \| Legacy Warrants
Class of Warrant or Right [Line Items]
Number of Shares of Common Stock Issuable (in shares)	20,220
Issuance On October 19, 2018
Class of Warrant or Right [Line Items]
Exercise Price (usd per share)	$ 19.78
Issuance On October 19, 2018 \| Legacy Warrants
Class of Warrant or Right [Line Items]
Number of Shares of Common Stock Issuable (in shares)	20,016
Issuance On March 13, 2019
Class of Warrant or Right [Line Items]
Exercise Price (usd per share)	$ 19.78
Issuance On March 13, 2019 \| Legacy Warrants
Class of Warrant or Right [Line Items]
Number of Shares of Common Stock Issuable (in shares)	5,000
Issuance On November 29, 2019 One
Class of Warrant or Right [Line Items]
Exercise Price (usd per share)	$ 12.00
Issuance On November 29, 2019 One \| Pre Funded Warrant
Class of Warrant or Right [Line Items]
Number of Shares of Common Stock Issuable (in shares)	1,250,000
Issuance On March 23, 2021
Class of Warrant or Right [Line Items]
Exercise Price (usd per share)	$ 8.70
Issuance On March 23, 2021 \| Pre Funded Warrant
Class of Warrant or Right [Line Items]
Number of Shares of Common Stock Issuable (in shares)	50,000
Issuance on November Nine Two Thousand Twenty One
Class of Warrant or Right [Line Items]
Number of Shares of Common Stock Issuable (in shares)	2,008,032
Exercise Price (usd per share)	$ 4.98
Issuance on March 3 2022
Class of Warrant or Right [Line Items]
Number of Shares of Common Stock Issuable (in shares)	766,666
Exercise Price (usd per share)	$ 1.80
Issuance on July 2022 1
Class of Warrant or Right [Line Items]
Number of Shares of Common Stock Issuable (in shares)	13,276,279
Exercise Price (usd per share)	$ 1.095
Issuance on July 6 2022 Two
Class of Warrant or Right [Line Items]
Number of Shares of Common Stock Issuable (in shares)	44,075,050
Exercise Price (usd per share)	$ 1.095
Issuance on December 9 2022
Class of Warrant or Right [Line Items]
Number of Shares of Common Stock Issuable (in shares)	32,137,448
Exercise Price (usd per share)	$ 1.50
Issuance on December 9 2022 2
Class of Warrant or Right [Line Items]
Number of Shares of Common Stock Issuable (in shares)	6,800,000
Exercise Price (usd per share)	$ 1.10
Issuance On May 19, 2023
Class of Warrant or Right [Line Items]
Exercise Price (usd per share)	$ 1.52
Issuance On May 19, 2023 \| Pre Funded Warrant
Class of Warrant or Right [Line Items]
Number of Shares of Common Stock Issuable (in shares)	8,263,157

Nature of the Business and Basis of Presentation	6 Months Ended
Nature of the Business and Basis of Presentation	Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business and Basis of Presentation	NATURE OF THE BUSINESS AND BASIS OF PRESENTATION X4 Pharmaceuticals, Inc. (together with its subsidiaries, the “Company”) is a biopharmaceutical company discovering, developing, and commercializing novel therapeutics for the treatment of rare diseases and those with limited treatment options, with a focus on conditions resulting from dysfunction of the immune system. On April 29, 2024, the Company announced that the FDA approved the Company’s New Drug Application (“NDA”) for mavorixafor, which is being marketed in the U.S. under the trade name XOLREMDI, for use as an oral, once-daily therapy in patients 12 years of age and older with WHIM syndrome (warts, hypogammaglobulinemia, infections, and myelokathexis), to increase the number of circulating mature neutrophils and lymphocytes. WHIM syndrome is a rare combined primary immunodeficiency and chronic neutropenic disorder. The Company is currently engaged in its U.S. launch of XOLREMDI in WHIM syndrome while also planning to seek regulatory approvals to commercialize mavorixafor outside of the U.S. The U.S. approval of XOLREMDI in the WHIM syndrome indication is the first for mavorixafor, which is an orally bioavailable selective antagonist of chemokine receptor CXCR4, a key regulator of the movement of immune cells throughout the body. Due to its ability to increase the mobilization of white blood cells from the bone marrow into the bloodstream, the Company believes that mavorixafor has the potential to provide therapeutic benefit across a variety of immune system disorders in addition to WHIM syndrome. As a result, the Company is completing a Phase 2 clinical trial evaluating the safety and efficacy of mavorixafor as a monotherapy and in combination with human granulocyte colony-stimulating factor (“G-CSF”) in people with certain chronic neutropenic disorders. Positive interim data from this Phase 2 trial were presented in June 2024. The Company initiated a global, pivotal Phase 3 clinical trial of mavorixafor (the 4WARD study) in the second quarter of 2024 that aims to evaluate the efficacy, safety, and tolerability of oral once-daily mavorixafor with or without G-CSF in people with congenital or acquired primary autoimmune and idiopathic chronic neutropenia who are experiencing recurrent and/or serious infections. The Company is headquartered in Boston, Massachusetts and has a research facility in Vienna, Austria. Going Concern Assessment—In accordance with the requirements of Accounting Standards Codification (“ASC”) 205-40, the Company has evaluated whether there are certain conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the condensed consolidated financial statements are issued. Although the Company has an approved drug product, sales of the Company’s drug product over the next 12 months will not be sufficient to fund the Company’s operating expenses. Since inception, the Company has incurred significant operating losses and negative cash flows from operations. During the quarter ended June 30, 2024, the Company sold a Priority Review Voucher (see Note 17) for $105.0 million in cash. As of June 30, 2024, the Company had $168.8 million of cash, cash equivalents and short-term marketable securities, and an accumulated deficit of $438.8 million. Net cash used in operating activities was $63.9 million for the six months ended June 30, 2024. The Company has a covenant under its Second Amended and Restated Loan and Security Agreement, as amended (the “Hercules Loan Agreement”) with Hercules Capital Inc. (“Hercules”), that requires that the Company currently maintain a minimum level of cash of $20 million, subject to adjustments beginning January 31, 2025, at which time the Company will be required to maintain a minimum level of cash equal to at least 20% of outstanding borrowings under the Hercules Loan Agreement, the (“Minimum Liquidity Covenant”). The Company has incurred losses and negative cash flows from operations since its inception, and the Company expects to continue to generate operating losses and negative cash flows from operations in the foreseeable future. Based on its current operating plan which includes estimates of anticipated cash inflows from product sales and cash outflows from operating expenses, the Company believes that its existing cash, cash equivalents and short-term marketable securities of $168.8 million as of June 30, 2024 will enable it to fund its planned operating expenses, debt service obligations and capital expenditures at least through the next 12 months from the issuance date of these condensed consolidated financial statements, while the Company observes the Minimum Liquidity Covenant. To finance its future operations beyond the one-year period following the issuance of these condensed consolidated financial statements, the Company will need to raise additional capital, which cannot be assured. Unless and until the Company reaches profitability in the future, it will require additional capital to fund its operations, which could be raised through a combination of equity offerings, debt financings, other third-party funding, marketing and distribution arrangements, or other collaborations and strategic alliances. If the Company is unable to obtain funding, it could be forced to delay, reduce, or eliminate some or all of its research and development programs, product portfolio expansion or commercialization efforts, which would adversely affect its business prospects, or it may be unable to continue operations. The Company is subject to risks common to companies in the biopharmaceutical industry including, but not limited to, uncertainties relating to conducting preclinical and clinical research and development, the manufacture and supply of products and product candidates for clinical and commercial use, obtaining and maintaining regulatory approvals and pricing and reimbursement for the Company’s products and product candidates, market acceptance, managing global growth and operating expenses, availability of additional capital, competition, obtaining and enforcing patents, stock price volatility, dependence on collaborative relationships and third-party service providers, dependence on key personnel, and from time to time government investigations, litigation, and potential product liability claims. Principles of Consolidation— The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, including X4 Pharmaceuticals (Austria) GmbH (“X4 Austria”), which is incorporated in Vienna, Austria, and X4 Therapeutics, Inc. All intercompany accounts and transactions have been eliminated. Unaudited Interim Condensed Consolidated Financial Statements— The condensed consolidated balance sheet at December 31, 2023 that is presented in these interim condensed consolidated financial statements was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America (“GAAP”). The accompanying condensed consolidated financial statements are unaudited. The accompanying unaudited interim condensed consolidated financial statements have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) for interim financial statements. Accordingly, certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. However, the Company believes that the disclosures are adequate to make the information presented not misleading. These unaudited interim condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements and the notes thereto for the year ended December 31, 2023 included in the 2023 Annual Report filed with the SEC on March 21, 2024. In the opinion of management, all adjustments, consisting only of normal recurring adjustments as necessary, for the fair statement of the Company’s condensed financial position, condensed results of its operations, and comprehensive loss and cash flows have been made. The results of operations for the three and six months ended June 30, 2024 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2024. Use of Estimates— The preparation of the Company’s consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of expenses during the reporting period. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses, the accrual of operational and financial license milestones (Note 3), the accrual of reserves for variable consideration related to product revenue, and the impairment or lack of impairment of long-lived assets including operating lease right-of-use assets and goodwill. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates when there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. As of the date of issuance of these consolidated financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgments or revise the carrying value of its assets or liabilities. Actual results could differ from those estimates, and any such differences may be material to the Company’s consolidated financial statements.

Intangible Assets, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
2024 (remainder of year)	$ 375
2025	750
2026	750
2027	750
2028	750
Thereafter	7,000
Total	$ 10,375	$ 0

Inventory

6 Months Ended

Jun. 30, 2024

Inventory Disclosure [Abstract]

Inventory

INVENTORY

Inventory consists of the following:


(in thousands)	June 30, 2024		December 31, 2023
Raw materials	$	612	—

Finished goods	219		—
Total inventory	$	831	$	—

Long-Term Debt - Schedule of Future Principal Payments and the Final Payments Due (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Aug. 02, 2023
Debt Disclosure [Abstract]
2024	$ 0
2025	0
2026	0
2027		$ 75,789
Principal amount of long-term debt	$ 75,789

Fair Value of Financial Assets and Liabilities - Narrative (Details)	Jun. 30, 2024 USD ($)
Measurement Input, Discount Rate
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value of derivative liability	$ 0.17

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

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+ Details

Leases - Schedule of Components of Lease Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Leases [Abstract]
Fixed operating lease cost	$ 489	$ 521	$ 978	$ 1,043
Total lease expense	489	521	978	1,043
Operating cash outflows from operating leases	343	345	687	691
Sublease income	$ 0	$ 48	$ 0	$ 97
Weighted-average remaining lease term-operating leases (in years)	2 years 8 months 12 days	3 years 7 months 6 days	2 years 8 months 12 days	3 years 7 months 6 days
Weighted-average discount rate-operating leases	11.50%	11.40%	11.50%	11.40%

Intangible Assets, Goodwill and Other

6 Months Ended

Jun. 30, 2024

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets, Net

INTANGIBLE ASSET, NET

As of June 30, 2024, the Company’s definite-lived intangible asset, which totaled $10.4 million, resulted from the capitalization of certain milestone payments made or accrued related to its license agreement for the intellectual property contained in its drug product. The Company amortizes the intangible asset to cost of revenue over the remaining life of the underlying patent protecting the intellectual property through 2038.

As of June 30, 2024, amortization expense for the next five years and beyond is summarized as follows (in thousands):


Year	Amortization expense
2024 (remainder of year)	$	375
2025	750
2026	750
2027	750
2028	750
Thereafter	7,000
Total	$	10,375

The Company began amortizing its finite-lived intangible assets in April 2024 over a 14-year period based on the expected patent exclusivity period for XOLREMDI. Amortization expense totaled $0.1 million for the three and six months ended June 30, 2024. Amortization expense is recorded as a component of cost of revenue on the consolidated statements of operations and comprehensive income (loss).

Cover Page - shares	6 Months Ended
Cover Page - shares	Jun. 30, 2024	Aug. 05, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2024
Document Transition Report	false
Entity File Number	001-38295
Entity Registrant Name	X4 PHARMACEUTICALS, INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-3181608
Entity Address, Address Line One	61 North Beacon Street
Entity Address, Address Line Two	4th Floor
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02134
City Area Code	857
Local Phone Number	529-8300
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	XFOR
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		168,499,514
Amendment Flag	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
Entity Central Index Key	0001501697
Current Fiscal Year End Date	--12-31

Fair Value of Financial Assets and Liabilities - Schedule of Assets and Liabilities Measured at Fair Value (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash equivalents	$ 151,552	$ 96,841
Fair value of derivative liability	9,233	15,693
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash equivalents	130,016	81,841
US Treasury Bill Securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash equivalents	21,536	15,000
Embedded derivative liability
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value of derivative liability	10	10
Class C Warrant Liability
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value of derivative liability	9,223	15,683
Level 1
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash equivalents	106,171	76,856
Fair value of derivative liability	0	0
Level 1 \| Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash equivalents	106,171
Level 1 \| US Treasury Bill Securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash equivalents	0	0
Level 1 \| Embedded derivative liability
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value of derivative liability	0	0
Level 1 \| Class C Warrant Liability
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value of derivative liability	0	0
Level 2
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash equivalents	45,381	19,985
Fair value of derivative liability	0	0
Level 2 \| Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash equivalents	23,845	4,985
Level 2 \| US Treasury Bill Securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash equivalents	21,536	15,000
Level 2 \| Embedded derivative liability
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value of derivative liability	0	0
Level 2 \| Class C Warrant Liability
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value of derivative liability	0	0
Level 3
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash equivalents	0	0
Fair value of derivative liability	9,233	15,693
Level 3 \| Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash equivalents	0
Level 3 \| US Treasury Bill Securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash equivalents	0	0
Level 3 \| Embedded derivative liability
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value of derivative liability	10	10
Level 3 \| Class C Warrant Liability
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value of derivative liability	$ 9,223	$ 15,683

Property and Equipment, Net - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 2,547	$ 2,364
Less: Accumulated depreciation and amortization	(1,739)	(1,619)
Property and equipment, net	808	745
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	228	228
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,381	1,301
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	263	160
Software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	24	24
Lab equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 651	$ 651

Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2024	Dec. 31, 2023
Number of Shares
Beginning balance (in shares)	6,008,541
Granted (in shares)	4,373,875
Forfeited (in shares)	(476,118)
Ending balance (in shares)	9,906,298	6,008,541
Number of shares Options, Exercisable (in shares)	1,813,063
Number of shares Options, Vested and expected to vest (in shares)	7,672,558
Weighted Average Exercise Price
Beginning balance (in usd per share)	$ 2.97
Granted (in usd per share)	1.09
Forfeited (in usd per share)	2.12
Ending balance (in usd per share)	2.18	$ 2.97
Weighted average exercise price, Exercisable (in usd per share)	6.55
Weighted average exercise price, Vested and expected to vest (in usd per share)	$ 2.47
Weighted average contractual term outstanding (in years)	8 years 9 months 18 days	8 years 7 months 6 days
Weighted average contractual term outstanding, Exercisable (in years)	6 years 2 months 12 days
Weighted average contractual term outstanding, Vested and expected to vest (in years)	8 years 7 months 6 days
Aggregate intrinsic value, Beginning balance	$ 24
Aggregate intrinsic value, Ending balance	0	$ 24
Aggregate intrinsic value, exercisable	0
Aggregate intrinsic value, vested and expected to vest	$ 0

CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK, REDEEMABLE COMMON STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]
Beginning balance, shares at Dec. 31, 2022		121,667,250
Beginning balance at Dec. 31, 2022	$ 74,051	$ 122	$ 450,786	$ (119)	$ (376,738)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted stock units (in shares)		540,238
Vesting of restricted stock units	0
Stock-based compensation expense	1,645		1,645
Net income (loss)	(24,020)				(24,020)
Ending balance, shares at Mar. 31, 2023		122,207,488
Ending balance at Mar. 31, 2023	51,676	$ 122	452,431	(119)	(400,758)
Beginning balance, shares at Dec. 31, 2022		121,667,250
Beginning balance at Dec. 31, 2022	74,051	$ 122	450,786	(119)	(376,738)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(79,732)
Ending balance, shares at Jun. 30, 2023		164,418,011
Ending balance at Jun. 30, 2023	67,535	$ 164	523,960	(119)	(456,470)
Beginning balance, shares at Mar. 31, 2023		122,207,488
Beginning balance at Mar. 31, 2023	51,676	$ 122	452,431	(119)	(400,758)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock and prefunded warrants in private placement equity transaction, net of issuance costs (in shares)		34,521,046
Issuance of common stock and prefunded warrants in private placement equity transaction, net of issuance costs	60,443	$ 35	60,408
Issuance of shares of common stock under employee stock purchase plan (in shares)		114,577
Issuance of shares of common stock under employee stock purchase plan	175		175
Exercise of stock and warrants (in shares)		7,476,345
Exercise of stock and warrants	8,811	$ 7	8,804
Vesting of restricted stock units (in shares)		98,555
Vesting of restricted stock units	0
Stock-based compensation expense	2,142		2,142
Net income (loss)	(55,712)				(55,712)
Ending balance, shares at Jun. 30, 2023		164,418,011
Ending balance at Jun. 30, 2023	67,535	$ 164	523,960	(119)	(456,470)
Beginning balance, shares at Dec. 31, 2023		167,434,595
Beginning balance at Dec. 31, 2023	51,099	$ 167	528,956	(119)	(477,905)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock and warrants	0		(1)
Vesting of restricted stock units (in shares)		503,186
Vesting of restricted stock units		$ 1
Stock-based compensation expense	1,739		1,739
Unrealized loss on marketable securities	(36)			(36)
Net income (loss)	(51,766)				(51,766)
Ending balance, shares at Mar. 31, 2024		167,937,781
Ending balance at Mar. 31, 2024	1,036	$ 168	530,694	(155)	(529,671)
Beginning balance, shares at Dec. 31, 2023		167,434,595
Beginning balance at Dec. 31, 2023	51,099	$ 167	528,956	(119)	(477,905)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	39,067
Ending balance, shares at Jun. 30, 2024		168,196,180
Ending balance at Jun. 30, 2024	94,451	$ 168	533,280	(159)	(438,838)
Beginning balance, shares at Mar. 31, 2024		167,937,781
Beginning balance at Mar. 31, 2024	1,036	$ 168	530,694	(155)	(529,671)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares of common stock under employee stock purchase plan (in shares)		235,068
Issuance of shares of common stock under employee stock purchase plan	158		158
Exercise of stock and warrants	0
Vesting of restricted stock units (in shares)		23,331
Stock-based compensation expense	2,428		2,428
Unrealized loss on marketable securities	(4)			(4)
Net income (loss)	90,833				90,833
Ending balance, shares at Jun. 30, 2024		168,196,180
Ending balance at Jun. 30, 2024	$ 94,451	$ 168	$ 533,280	$ (159)	$ (438,838)

Common Stock Warrants - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2024	Dec. 31, 2023	Jul. 06, 2022	Mar. 03, 2022	Mar. 23, 2021	Nov. 02, 2020	Nov. 29, 2019
Class of Warrant or Right [Line Items]
Common stock, shares authorized	500,000,000	500,000,000
Common stock, par value (in usd per share)	$ 0.001	$ 0.001
Dividends on common stock declared or paid	$ 0
Class of Warrant or Right, Additional Exercise Price of Warrants or Rights			$ 0.001	$ 0.01		$ 0.01	$ 0.001
Q1 2022 Private Placement
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Additional Exercise Price of Warrants or Rights					$ 0.01

Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2024
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation— The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, including X4 Pharmaceuticals (Austria) GmbH (“X4 Austria”), which is incorporated in Vienna, Austria, and X4 Therapeutics, Inc. All intercompany accounts and transactions have been eliminated.
Use of Estimates	Use of Estimates— The preparation of the Company’s consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of expenses during the reporting period. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses, the accrual of operational and financial license milestones (Note 3), the accrual of reserves for variable consideration related to product revenue, and the impairment or lack of impairment of long-lived assets including operating lease right-of-use assets and goodwill. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates when there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. As of the date of issuance of these consolidated financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgments or revise the carrying value of its assets or liabilities. Actual results could differ from those estimates, and any such differences may be material to the Company’s consolidated financial statements.
Revenue Recognition	Revenue Recognition— The Company records revenue using the guidance of ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”), as amended. Upon the approval by the FDA of the sales and marketing of the Company’s lead product candidate, revenue related to its sale and distribution is accounted for under ASC 606. The Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the Company determines it expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (1) identify the customer and contract with the customer; (2) identify the performance obligations in the contract; (3) determine the transaction price, adjusted for variable consideration resulting from potential returns, rebates, discounts, and down-stream charges; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when the Company satisfies its performance obligations, which is upon shipment of the finished product to the customer. The Company currently sells its product to one U.S. customer, which is a specialty pharmacy. The specialty pharmacy dispenses the Company’s drug product to patients in the U.S.. The Company records revenue when the specialty pharmacy obtains control over the promised good, which occurs at a point in time, typically upon delivery to the specialty pharmacy. The Company has concluded that it provides one performance obligation in its contract with its customer: the delivery of drug product that has been approved for sale and distribution by the applicable regulatory authority. As part of the accounting for its contract arrangements, the Company makes significant judgments, primarily related to the estimation of the amount of variable consideration to include in the transaction price upon delivery of the Company’s drug product. The variable consideration includes estimates for discounts, product returns, rebates that will be due to U.S. federal and state payors, such as Medicaid, based on agreements that the Company has with these payors who provide medical insurance to the end patient, and estimated co-pay assistance payments for patients who enroll in the Company’s patient assistance program. These variable payments are considered a reduction of the Company’s transaction price with its customer and must be estimated at the time the Company’s product is delivered to the customer. The Company determines the amount of variable consideration by using the expected value method. Net revenue recognized for each period is the amount for which, based on management’s estimate, it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates these estimates based on new information and actual operational trends and if necessary, adjusts these variable consideration estimates. Any such adjustments are recorded on a cumulative catch-up basis in the period of the adjustment.
Goodwill	Goodwill—Goodwill is tested for impairment at the reporting unit level annually in the fourth quarter, or more frequently when events or changes in circumstances indicate that the asset might be impaired. Examples of such events or circumstances include, but are not limited to, a significant adverse change in legal or business climate, an adverse regulatory action or unanticipated competition. The Company has determined that it operates in a single operating segment and has a single reporting unit. The Company assesses qualitative factors to determine whether the existence of events or circumstances would indicate that it is more likely than not that the fair value of the reporting unit is less than its carrying amount. If after assessing the totality of events or circumstances, the Company were to determine that it is more likely than not that the fair value of the reporting unit is less than its carrying amount, then the Company would perform an interim quantitative impairment test, whereby the Company compares the fair value of the reporting unit to its carrying value. If the fair value of the reporting unit exceeds the carrying value of its net assets, goodwill is not impaired, and no further testing is required. If the fair value of the reporting unit is less than its carrying value, the Company measures the amount of impairment loss, if any, as the excess of the carrying value over the fair value of the reporting unit. There were no triggering events during the three months ended June 30, 2024 that necessitated an interim impairment test of goodwill.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Standards In November 2023, the Financial Accounting Standards Board (“FASB”) issued ASU 2023-07, Segment Reporting (Topic 326) Improvements to Reportable Segment Disclosures (“ASU 2023-07”). Among other disclosure enhancements, ASU 2023-07 requires that entities with one reportable segment, such as the Company, disclose general information for its reportable segment, such as the title and position of the individual identified as the Chief Operating Decision Maker (“CODM”), which for the Company is the Chief Executive Officer, the types of products and services provided by the reportable segment, the measure of profit or loss reviewed by the CODM to evaluate performance of the reportable segment and other financial results such as interest income, interest expense, and depreciation associated with the reportable segment. The amendments in ASU 2023-07 will become effective for the Company in its consolidated financial statements as of and for the three years ending December 31, 2024 and must be adopted retrospectively. Although the Company continues to evaluate the potential impact of ASU 2023-07, the Company does not believe that the adoption of ASU 2023-07 will have a material impact on its consolidated financial statement when adopted. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740) Improvements to Income Tax Disclosures (“ASU 2023-09”). The amendments in ASU 2023-09 require that entities on an annual basis disclose specific categories in the income tax rate reconciliation and provide additional information for reconciling items if the effect of those reconciling items that exceed a certain threshold. ASU 2023-09 will also require more disaggregated disclosures related to income taxes paid. The amendments in ASU 2023-09 will become effective for the Company in its December 31, 2024 consolidated financial statements. Although the Company continues to evaluate the impact of ASU 2023-09, the Company expects that these amendments will require further disclosures in the tax footnote of its annual consolidated financial statements and will not have a material impact on its consolidated financial states when adopted.
Research and Development Expense, Policy
Inventory	Inventory— Prior to receiving approval from the FDA in April 2024 to sell XOLREMDI (mavorixafor) in the United States, the Company expensed all costs incurred related to the manufacture of mavorixafor as research and development expense due to the inherent risks associated with the development of a drug candidate, the uncertainty about the regulatory approval process and the lack of history for the Company in obtaining of regulatory approval of drug candidates. The Company has capitalized inventory-related costs that were incurred subsequent to FDA approval, such as the bottling, labelling, and packaging of drug product, and the acquisition of raw materials for the production of drug substance to be used in commercial drug product. In connection therewith, the Company values inventories at the lower of cost or estimated net realizable value. The Company determines the cost of inventories on a first-in, first-out (“FIFO”) basis. Raw materials and work in process include all inventory costs prior to packaging, and labelling, including raw materials and the active pharmaceutical ingredient used in the drug product. Finished goods include packaged and labelled drug products designated for commercial distribution. Clinical drug supplies are expensed to research and development. Raw materials and work in process that may be used for either research and development or commercial sale are classified as inventory until the material is consumed or otherwise allocated for research and development. If the material may only be used for research and development, it is expensed as research and development.
Intangible Assets	Intangible Assets, Net— Definite-lived intangible assets related to capitalized milestones under license agreements are amortized on a straight-line basis, which aligns with the pattern over which the economic benefit of the intangible assets are consumed, over their remaining useful lives, which are estimated to be the remaining patent life. If the Company’s estimate of the product’s useful life is shorter than the remaining patent life, then a shorter period is used. Amortization expense is recorded as a component of cost of revenue on the consolidated statements of operations and comprehensive income (loss).

- Definition

Disclosure of inventory accounting policy for inventory classes, including, but not limited to, basis for determining inventory amounts, methods by which amounts are added and removed from inventory classes, loss recognition on impairment of inventories, and situations in which inventories are stated above cost.

+ References + Details

- Definition

Disclosure of accounting policy for revenue from contract with customer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-17

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Name Accounting Standards Codification
-Section 50
-Paragraph 19
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-19

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-18

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (b)
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-URI https://asc.fasb.org//1943274/2147479806/606-10-50-18

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Name Accounting Standards Codification
-Section 50
-Paragraph 20
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-20

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Name Accounting Standards Codification
-Section 50
-Paragraph 20
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-20

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 20
-Subparagraph (c)
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-URI https://asc.fasb.org//1943274/2147479806/606-10-50-20

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Paragraph 20
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Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (e)
-SubTopic 10
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483426/235-10-50-4

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org//606/tableOfContent

+ Details

Common Stock Warrants

6 Months Ended

Jun. 30, 2024

Equity [Abstract]

Common Stock Warrants

COMMON STOCK AND COMMON STOCK WARRANTS

As of June 30, 2024, the Company’s Restated Certificate of Incorporation authorized the Company to issue 500 million shares of common stock, par value $0.001 per share. The voting, dividend, and liquidation rights of the holders of the Company’s common stock are subject to and qualified by the rights, powers and preferences of the holders of any preferred stock that may be issued. Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to receive dividends, as may be declared by the board of directors, if any. No cash dividends have been declared or paid to date.

Warrants and Pre-Funded Warrants

In connection with public and private sales of shares of its common stock, the Company has issued warrants and pre-funded warrants, which are exercisable for the purchase shares of the Company’s common stock. All outstanding warrants and pre-funded warrants are currently exercisable and do not have price reset provisions. Upon the closing of these public and private offerings, the Company received approximately 99% of the exercise price for the pre-funded warrants, for which the remaining exercise price is equal to or less than $0.01 per share. There were no warrant exercises during the three or six months ended June 30, 2024.

As of June 30, 2024, the Company’s outstanding warrants and pre-funded warrants to purchase shares of common stock consisted of the following:


Issuance Date	Number of Shares of Common Stock Issuable	Exercise Price			Expiration Date
October 25, 2016	5,155	$	19.78		October 24, 2026
December 28, 2017	115,916	$	19.78		December 28, 2027
September 12, 2018	20,220	$	19.78		September 12, 2028
October 19, 2018	20,016	$	19.78		October 19, 2028
March 13, 2019	5,000	$	19.78		March 12, 2029


November 29, 2019	1,250,000	$	12.00	(a)	n/a
March 23, 2021	50,000	$	8.70	(b)	n/a
November 9, 2021	2,008,032	$	4.98	(c)	n/a
March 3, 2022	766,666	$	1.80	(d)	n/a
July 6, 2022	13,276,279	$	1.095	(e)	n/a
July 6, 2022	44,075,050	$	1.095		July 6, 2027
December 9, 2022	32,137,448	$	1.50		December 9, 2027
December 9, 2022	6,800,000	$	1.10	(f)	n/a
May 18, 2023	8,263,157	$	1.52	(g)	n/a
	108,792,939

(a) In November 2019, the Company received $11.999 per pre-funded warrant, or $21.0 million in aggregate proceeds. Each pre-funded

warrant may be exercised for an additional $0.001 per pre-funded warrant. (b) In March 2021, the Company received $8.69 per pre-funded warrant, or $435 thousand in aggregate proceeds. Each pre-funded warrant may be exercised for an additional $0.01 per pre-

funded warrant. (c) In November 2021, the Company received $4.97 per pre-funded warrant, or $10.0 million in aggregate proceeds. Each pre-funded warrant may be exercised for an additional $0.01 per pre-funded warrant. (d) In March 2022, the Company received $1.79 per pre-funded warrant, or $1.4 million in aggregate proceeds. Each pre-funded warrant may be exercised for an additional $0.01 per pre-funded warrant. (e) In July 2022, the Company received $1.094 per pre-funded warrant, or $14.5 million in aggregate proceeds. Each pre-funded warrant may be exercised for an additional $0.001 per pre-funded warrant. (f) In December 2022, the Company received $1.099 per pre-funded warrant, or $7.5 million in aggregate proceeds. (g) In May 2023, the Company received $1.519 per pre-funded warrant, or $12.6 million in aggregate proceeds. Each pre-funded warrant may be exercised for an additional $0.001 per pre-funded warrant.

Inventory (Tables)

6 Months Ended

Jun. 30, 2024

Inventory Disclosure [Abstract]

Schedule of Inventory, Current

Inventory consists of the following:


(in thousands)	June 30, 2024		December 31, 2023
Raw materials	$	612	—

Finished goods	219		—
Total inventory	$	831	$	—

Stock-Based Compensation - Schedule of Assumptions Used in Black-Scholes Option-Pricing Model to Determine Grant-date Fair Value of Stock Options Granted (Detail)			3 Months Ended		6 Months Ended
	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate (in percentage)			4.40%	4.00%	4.20%	3.80%
Expected term (in years)			6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days	6 years
Expected volatility (in percentage)			96.50%	93.40%	96.00%	92.10%
Expected dividend yield (in percentage)			0.00%	0.00%	0.00%	0.00%
Class C Warrant Liability
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate (in percentage)	4.40%	3.90%
Expected term (in years)	3 years 4 months 24 days	3 years 10 months 24 days
Expected volatility (in percentage)	100.50%	96.20%
Expected dividend yield (in percentage)	0.00%	0.00%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2024

Accounting Policies [Abstract]

Schedule of Restricted Cash

Restricted Cash


(in thousands)	As of June 30, 2024		As of December 31, 2023

Letter of credit security: Waltham lease	$	—	$	250
Letter of credit security: Vienna Austria lease	205		211
Letter of credit security: Boston lease	573		571
Total restricted cash	$	778	$	1,032
Restricted cash included in prepaid expenses and other current assets	$	—	$	250
Restricted cash included in other assets	$	778	$	782

Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash

The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the consolidated balance sheets to the sum to the total of amounts shown in the Company’s consolidated statements of cash flows as of June 30, 2024 and December 31, 2023:


(in thousands)	June 30, 2024		December 31, 2023
Cash and cash equivalents	$	147,218	$	99,216
Restricted cash, current (included within prepaid expenses and other current assets)	—		250
Restricted cash, non-current	778		782
Total cash, cash equivalents and restricted cash	$	147,996	$	100,248

Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2024

Share-Based Payment Arrangement [Abstract]

Stock Option Valuation

The following table presents, on a weighted average basis, the assumptions used in the Black-Scholes option-pricing model to determine the grant-date fair value of stock options granted to employees, directors and non-employees.


	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023		2024		2023
Risk-free interest rate	4.4	%	4.0	%	4.2	%	3.8	%
Expected term (in years)	6.1		6.1		6.1		6.0
Expected volatility	96.5	%	93.4	%	96.0	%	92.1	%
Expected dividend yield	0	%	0	%	0	%	0	%

Summary of Stock Option Activity

The following table summarizes the Company’s stock option activity for the six months ended June 30, 2024:


	Number of Shares	Weighted Average Exercise Price		Weighted Average Contractual Term (Years)	Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2023	6,008,541	$	2.97	8.6	$	24
Granted	4,373,875	1.09

Forfeited and Expired	(476,118)	2.12
Outstanding as of June 30, 2024	9,906,298	$	2.18	8.8	$	—
Exercisable as of June 30, 2024	1,813,063	$	6.55	6.2	$	—
Vested and expected to vest as of June 30, 2024	7,672,558	$	2.47	8.6	$	—

Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity

Restricted Stock Units— The following table summarizes the Company's restricted stock unit activity for the six months ended June 30, 2024:


			Number of Shares
Unvested as of December 31, 2023			3,118,824
Granted			6,242,459
Vested			(829,851)
Forfeited			(313,961)
Unvested as of June 30, 2024			8,217,471

Summary of Stock-Based Compensation Expense Classification

Stock-based compensation expense was classified in the condensed consolidated statements of operations and comprehensive income (loss) as follows:


	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2024		2023		2024		2023
Research and development expense	$	1,182	$	1,120	$	1,965	$	1,951
Selling, general and administrative expense	1,246		1,022		2,202		1,836
Total stock-based compensation	$	2,428	$	2,142	$	4,167	$	3,787

Share-Based Payment Arrangement, Option and Stock Appreciation Rights, Activity

Stock Appreciation Rights— On February 13, 2024, (the “Grant Date”), the compensation committee of the Board of Directors approved the grant of stock appreciation rights (“SARs”), pursuant to the 2017 Plan, to the Company’s executive officers. The SARs have a measurement price per SAR equal to $0.92, the closing price per share of the Company’s common stock on the Grant Date, and each grant of SARs will have a maximum term of ten years from the Grant Date. Unless otherwise determined by the Board of Directors, the SARs will be settled in cash upon exercise. The settlement value will be based on the difference between the closing price of the Company’s common stock on the date of settlement less $0.92 multiplied by the number of SARs exercised. The SARs will vest and become exercisable in equal annual installments on the first, second, and third anniversaries of the Grant Date, subject to the recipient remaining an employee of the Company through and including each applicable vesting date.

Nature of the Business and Basis of Presentation - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Business Acquisition [Line Items]
Cash, Cash Equivalents, and Short-Term Investments	$ 168,800	$ 168,800
Accumulated deficit	(438,838)	(438,838)		$ (477,905)
Net cash used in operating activities	(63,900)	(63,874)	$ (47,937)
Min Cash Test Date 1 \| Hercules Second Amended Loan Agreement
Business Acquisition [Line Items]
Line of Credit, Covenant, Minimum Cash	$ 20,000	$ 20,000

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

Intangible Assets, Net (Tables)

6 Months Ended

Jun. 30, 2024

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense

As of June 30, 2024, amortization expense for the next five years and beyond is summarized as follows (in thousands):


Year	Amortization expense
2024 (remainder of year)	$	375
2025	750
2026	750
2027	750
2028	750
Thereafter	7,000
Total	$	10,375

Stock-Based Compensation - Restricted Stock Units (Details) - Restricted Stock Units (RSUs)	6 Months Ended
	Jun. 30, 2024 shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Nonvested beginning balance (in shares)	3,118,824
Granted (in shares)	6,242,459
Vested (in shares)	(829,851)
Forfeited (in shares)	(313,961)
Nonvested ending balance (in shares)	8,217,471

Long-Term Debt

6 Months Ended

Jun. 30, 2024

Debt Disclosure [Abstract]

Long-Term Debt

LONG-TERM DEBT

Long-term debt consisted of the following:


(in thousands)	June 30, 2024		December 31, 2023
Principal amount of long-term debt	$	75,000	$	55,000
Debt discount, net of accretion	(759)		(917)
Cumulative accretion of end of term payments	789		487
Long-term debt	$	75,030	$	54,570

Hercules Loan Agreement

The Company entered into a Loan and Security Agreement, as most recently amended, with Hercules Capital, Inc., the (“Hercules Loan Agreement”). The Hercules Loan Agreement provides for an aggregate term loan facility of up to $115.0 million, under which the Company has borrowed an aggregate of $75.0 million of term loans, representing the maximum borrowings allowable as of June 30, 2024. During the quarter ended June 30, 2024, the Company borrowed an additional $20.0 million term loan, which became available based on the achievement of an operational milestone. The Hercules Loan Agreement allows for $40.0 million of additional borrowings:

(i.) an additional tranche of $7.5 million, which will become available following achievement of a certain clinical development-related milestone through the earlier of (a) 45 days following achievement of such milestone and (b) December 15, 2024; and

(ii.) an additional tranche of up to $32.5 million, which will be available subject to approval by Hercules in its sole discretion.

Borrowings under the Hercules Loan Agreement accrue interest at a variable rate equal to the greater of (i) 10.15% or (ii) The Wall Street Journal prime rate plus 3.15%. In an event of default and until such event is no longer continuing, the interest rate applicable to borrowings would be increased by 4.0%. Borrowings are repayable in monthly interest-only payments through July 1, 2027, which is the maturity date of the loans. At the Company’s option, the Company may prepay all, but not less than all, of the outstanding borrowings, subject to a prepayment premium of 2% during the 12-month period ending January 5, 2025 and 1% thereafter. In addition, the Hercules Loan Agreement provides for payment of end-of-term fees of $2.8 million plus 3.5% of the aggregate principal amount of future loans drawn, if any, payable upon the earlier of maturity or the repayment in full of all obligations under the Hercules Loan Agreement. Borrowings under the Hercules Loan Agreement are collateralized by substantially all of the Company’s personal property and other assets except for its intellectual property (but including rights to payment and proceeds from the sale, licensing or disposition of the intellectual property).

Under the Hercules Loan Agreement, the Company has agreed to affirmative and negative covenants. Prior to January 31, 2025, the Company must maintain cash in an account or accounts in which Hercules has a first priority security interest (“Qualified Cash”) in an aggregate amount equal to at least $20.0 million.

•On and after January 31, 2025, such amount must equal at least 20% of the aggregate principal amount of loans outstanding under the Hercules Loan Agreement.

•From and after January 31, 2025, the Company must maintain trailing six month net product revenue of at least 55% of its forecast as approved by the Company’s Board of Directors (the “Performance Covenant”). However, the Performance Covenant will be waived during any period in which:

(i.) the Company maintains Qualified Cash in an aggregate amount equal to at least 75% of loans outstanding under the Amended Loan Agreement or

(ii.) both (a) the Company maintains a market capitalization (as defined in the Hercules Loan Agreement) of at least $450.0 million and (b) the Company maintains Qualified Cash, as defined in the Hercules Loan Agreement, in an aggregate amount equal to at least 45% of loans outstanding.

The Hercules Loan Agreement also restricts the Company’s ability to incur additional indebtedness, pay dividends, encumber its intellectual property, or engage in certain fundamental business transactions, such as mergers or acquisitions of other businesses, with certain exceptions.

The Company recognized interest expense under the Hercules Loan Agreement as follows:


(in thousands)	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023		2024		2023
Total interest expense	$	2,176	$	1,148	$	4,049	$	2,257
Non-cash interest expense	$	207	$	219	$	461	$	444

The annual effective interest rate of the Hercules Loan Agreement as of June 30, 2024 is 12.6%. There were no principal payments due or paid under the Hercules Loan Agreement during the three months ended June 30, 2024. During the quarter ended June 30, 2024, the Company borrowed an additional $20.0 million term loan, which became available based on the achievement of an operational milestone.

As of June 30, 2024, future principal and accrued end-of-term payments of $75.8 million under the Hercules Loan Agreement are due on July 1, 2027.


(in thousands),
Year Ending December 31,	Total
2024	$	—
2025	—
2026	—

2027	75,789
Long-term debt	$	75,789

Intangible Assets, Net - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2024	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Finite-Lived Intangible Assets, Net	$ 10,375	$ 10,375	$ 0
Finite-Lived Intangible Asset, Useful Life	14 years	14 years
Amortization of Intangible Assets	$ 100	$ 100

Gain on Sale of Non-Financial Asset	6 Months Ended
Gain on Sale of Non-Financial Asset	Jun. 30, 2024
Discontinued Operations and Disposal Groups [Abstract]
Gain on Sale of Non-Financial Asset	GAIN ON SALE OF NON-FINANCIAL ASSETDuring the quarter ended June 30, 2024, the Company entered into contractual arrangement with a third party that transferred the rights to a Priority Review Voucher (“PRV”) awarded to the Company by FDA under its Rare Pediatric Disease program upon the approval of XOLREMDI. The FDA awards PRVs to sponsors of rare pediatric disease product applications that meet certain criteria to encourage development of new drugs and biologics for the prevention and treatment of rare pediatric diseases.The PRV is accounted for as an intangible asset with no accounting cost basis. The third party purchased the PRV for $105.0 million. There were no fees associated with the sale and the Company has no continuing obligations with respect to the PRV. The Company concluded that the third party is “non-customer” as the underlying PRV is not an output of the Company's ordinary commercial activities. Accordingly, the Company accounted for this transaction under ASC Topic 610-20, Gains and Losses from the Derecognition of Nonfinancial Assets (“ASC 610-20”). As a result of the transfer of control of the PRV to the third party, the Company derecognized the associated intangible asset and recorded a gain through “gain on transfer of nonfinancial assets.”

Revenue - Product Reserve Accounts (Details) $ in Thousands	6 Months Ended
Revenue - Product Reserve Accounts (Details) $ in Thousands	Jun. 30, 2024 USD ($)
Disaggregation of Revenue [Line Items]
Beginning balance at December 31, 2023	$ 0
Provision related to revenue in the three and six month period ended June 30, 2024	171
Credits and payments made during the period	(41)
Balance as of June 30, 2024	130
Rebates and Discounts
Disaggregation of Revenue [Line Items]
Beginning balance at December 31, 2023	0
Provision related to revenue in the three and six month period ended June 30, 2024	44
Credits and payments made during the period	(21)
Balance as of June 30, 2024	23
Co-Pay Assistance
Disaggregation of Revenue [Line Items]
Beginning balance at December 31, 2023	0
Provision related to revenue in the three and six month period ended June 30, 2024	35
Credits and payments made during the period	(20)
Balance as of June 30, 2024	15
Product Returns
Disaggregation of Revenue [Line Items]
Beginning balance at December 31, 2023	0
Provision related to revenue in the three and six month period ended June 30, 2024	92
Credits and payments made during the period	0
Balance as of June 30, 2024	$ 92

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Net Loss per Share - Summary of Basic and Diluted Net loss per Share Attributable to Common Stockholders (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Numerator:
Net income (loss)	$ 90,833	$ (51,766)	$ (55,712)	$ (24,020)	$ 39,067	$ (79,732)
Denominator:
Weighted average shares of common stock outstanding—basic	200,440,473		168,737,764		200,216,035	157,415,524
Net loss per share attributable to common stockholders—basic	$ 0.45		$ (0.33)		$ 0.20	$ (0.51)
Dilutive potential common shares	360,838		0		239,848	0
Weighted average shares of common stock outstanding—diluted	200,801,311		168,737,764		200,455,883	157,415,524
Net loss per share attributable to common stockholders—diluted	$ 0.45		$ (0.33)		$ 0.19	$ (0.51)
Restricted Stock
Denominator:
Effective of dilutive securities (in shares)	244,804		0		163,072	0
Employee Stock
Denominator:
Effective of dilutive securities (in shares)	116,034		0		76,776	0

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Pay vs Performance Disclosure
Net income (loss)	$ 90,833	$ (51,766)	$ (55,712)	$ (24,020)	$ 39,067	$ (79,732)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-28

Reference 36: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1A

Reference 37: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1B

Reference 38: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(20))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 39: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

+ Details

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued employee compensation and benefits	$ 7,175	$ 8,195
Accrued external research and development expenses	5,439	2,804
Accrued royalty and milestone payments	3,037	0
Accrued professional fees	2,538	1,195
Accrued revenue reserves	130	0
Other	1,425	622
Total accrued expenses	$ 19,744	$ 12,816

Net Loss per Share (Tables)

6 Months Ended

Jun. 30, 2024

Earnings Per Share [Abstract]

Summary of Basic and Diluted Net Loss per Share Attributable to Common Stockholders

Basic and diluted net income (loss) per share was calculated as follow:


	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands, except share and per share data)	2024		2023		2024		2023
Numerator:


Net income (loss)	$	90,833	$	(55,712)	$	39,067	$	(79,732)
Denominator:
Weighted average shares of common stock outstanding—basic	200,440,473		168,737,764		200,216,035		157,415,524
Net income (loss) per share— basic	$	0.45	$	(0.33)	$	0.20	$	(0.51)
Effective of dilutive securities
Time-based restricted stock units	244,804		—		163,072		—

Employee stock purchase plan	116,034		—		76,776		—
Dilutive potential common shares	360,838		—		239,848		—
Weighted average shares of common stock outstanding—diluted	200,801,311		168,737,764		200,455,883		157,415,524
Net income (loss) per share— diluted	$	0.45	$	(0.33)	$	0.19	$	(0.51)

Schedule of Anti-dilutive Securities Excluded from Computation of Diluted Net Loss per Share Attributable to Common Stockholders


	Three Months Ended June 30,		Six Months Ended June 30,
	2024	2023	2024	2023
Options to purchase shares of common stock	9,906,298	3,583,186	9,906,298	3,583,186
Unvested restricted stock units	7,800,805	5,859,232	7,800,805	5,859,232
Warrants to purchase shares of common stock (excluding prefunded warrants, which are included in basic shares outstanding)	76,378,805	80,246,459	76,378,805	80,246,459
	94,085,908	89,688,877	94,085,908	89,688,877

Property and Equipment, Net

6 Months Ended

Jun. 30, 2024

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

PROPERTY AND EQUIPMENT, NET

Property and equipment, net consisted of the following:


(in thousands)	June 30, 2024		December 31, 2023
Leasehold improvements	$	228	$	228
Furniture and fixtures	1,381		1,301
Computer equipment	263		160
Software	24		24
Lab equipment	651		651
	2,547		2,364
Less: Accumulated depreciation and amortization	(1,739)		(1,619)
	$	808	$	745

Depreciation and amortization expense related to property and equipment was $131 thousand and $253 thousand for the six months ended June 30, 2024 and 2023, respectively.

Common Stock Warrants (Tables)

6 Months Ended

Jun. 30, 2024

Equity [Abstract]

Schedule of Warrants

As of June 30, 2024, the Company’s outstanding warrants and pre-funded warrants to purchase shares of common stock consisted of the following:


Issuance Date	Number of Shares of Common Stock Issuable	Exercise Price			Expiration Date
October 25, 2016	5,155	$	19.78		October 24, 2026
December 28, 2017	115,916	$	19.78		December 28, 2027
September 12, 2018	20,220	$	19.78		September 12, 2028
October 19, 2018	20,016	$	19.78		October 19, 2028
March 13, 2019	5,000	$	19.78		March 12, 2029


November 29, 2019	1,250,000	$	12.00	(a)	n/a
March 23, 2021	50,000	$	8.70	(b)	n/a
November 9, 2021	2,008,032	$	4.98	(c)	n/a
March 3, 2022	766,666	$	1.80	(d)	n/a
July 6, 2022	13,276,279	$	1.095	(e)	n/a
July 6, 2022	44,075,050	$	1.095		July 6, 2027
December 9, 2022	32,137,448	$	1.50		December 9, 2027
December 9, 2022	6,800,000	$	1.10	(f)	n/a
May 18, 2023	8,263,157	$	1.52	(g)	n/a
	108,792,939

(a) In November 2019, the Company received $11.999 per pre-funded warrant, or $21.0 million in aggregate proceeds. Each pre-funded

Stock-Based Compensation Summary of Stock-Based Compensation Expense Classification (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	$ 2,428	$ 2,142	$ 4,167	$ 3,787
Research and development expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	1,182	1,120	1,965	1,951
Selling, general and administrative expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	$ 1,246	$ 1,022	$ 2,202	$ 1,836

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Leases (Tables)

6 Months Ended

Jun. 30, 2024

Leases [Abstract]

Schedule of Components of Lease Expense

The components of lease expense for the three and six months ended June 30, 2024 and 2023 were as follows:


(dollars in thousands)	Three Months Ended June 30,						Six Months Ended June 30,
Lease Cost	2024			2023			2024			2023
Fixed operating lease cost	$	489		$	521		$	978		$	1,043

Total lease expense	$	489		$	521		$	978		$	1,043
Other information

Operating cash outflows from operating leases	$	343		$	345		$	687		$	691
Sublease income	$	—		$	48		$	—		$	97
Weighted-average remaining lease term—operating leases	2.7			3.6			2.7			3.6
Weighted-average discount rate—operating leases	11.5		%	11.4		%	11.5		%	11.4		%

Schedule of Maturities of Lease Liabilities

Maturities of lease liabilities due under lease agreements that have commenced as of June 30, 2024 are as follows (in thousands):


Maturity of lease liabilities	Operating Leases
2024 (remainder of the year)	$	688
2025	1,402
2026	1,332
2027	280
2028	47

Total lease payments	3,749
Less: interest	(551)
Total operating lease liabilities as of June 30, 2024	$	3,198

Fair Value of Financial Assets and Liabilities - Debt Securities Available-for-Sale (Details) $ in Thousands	Jun. 30, 2024 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	$ 21,578
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax	0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	42
Debt Securities, Available-for-Sale	21,536
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	2,210
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax	0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	4
Debt Securities, Available-for-Sale	2,206
Federal Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	19,368
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax	0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	38
Debt Securities, Available-for-Sale	$ 19,330

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Common stock, par value (in usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	168,196,180	167,434,595
Common stock, shares outstanding	168,196,180	167,434,595

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Cash flows from operating activities:
Net income (loss)	$ 39,067	$ (79,732)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	4,167	3,787
Depreciation and amortization expense	256	253
Gain on sale of non-financial asset (Note 17)	(105,000)	0
Non-cash lease expense	778	775
Accretion of debt discount	461	438
Change in fair value of warrant liability	(6,460)	24,421
Other	(281)	(41)
Changes in operating assets and liabilities:
Inventory, Net	(831)	0
Prepaid expenses, other current assets and research and development incentive receivable	1,398	479
Accounts payable	(944)	(2,815)
Accrued expenses and other long-term liabilities	4,001	5,024
Lease liabilities	(486)	(526)
Net cash used in operating activities	(63,874)	(47,937)
Cash flows from investing activities:
Acquisition of intangible asset	(7,000)	0
Proceeds from sale of non-financial asset	105,000	0
Purchase of marketable securities	(13,267)	(4,876)
Sales and maturities of marketable securities	7,000	0
Acquisition of property and equipment	(193)	(17)
Net cash provided by (used in) investing activities	91,540	(4,893)
Cash flows from financing activities:
Proceeds from Issuance of Common Stock	159	8,613
Fees paid to amendment loan agreement and issuance costs related to the sale of warrants	0	(381)
Repayments of borrowings and accrued end-of-term fees under loan and security agreement	0	(1,300)
Proceeds from borrowings under loan and security agreement	20,000	0
Proceeds from sale of common stock, warrants and pre-funded warrants, net of issuance costs	0	60,282
Net cash provided by financing activities	20,159	67,214
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(77)	44
Net increase in cash, cash equivalents and restricted cash	47,748	14,428
Cash, cash equivalents and restricted cash at beginning of period	100,248	123,028
Cash, cash equivalents and restricted cash at end of period	147,996	137,456
Supplemental Cash Flow Information [Abstract]
Debt Issuance Costs Incurred During Noncash or Partial Noncash Transaction	0	283
Acquisition of intangible assets included in accrued expenses and other liabilities	$ 3,500	$ 0

Fair Value of Financial Assets and Liabilities

6 Months Ended

Jun. 30, 2024

Fair Value Disclosures [Abstract]

Fair Value of Financial Assets and Liabilities

FAIR VALUE OF FINANCIAL ASSETS AND LIABILITIES

The following tables present information about the Company’s financial assets and liabilities measured at fair value on a recurring basis and indicate the level of the fair value hierarchy used to determine such fair values:


	Fair Value Measurements as of June 30, 2024 Using:
(in thousands)	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents—money market funds and U.S. Treasury bills	$	106,171	$	23,845	$	—	$	130,016
Marketable securities— U.S. Treasury notes, U.S. Treasury bills, and federal government agency notes	—		21,536		—		21,536
	$	106,171	$	45,381	$	—	$	151,552
Liabilities:
Embedded derivative liability	$	—	$	—	$	10	$	10
Class C warrant liability	—		—		9,223		9,223
	$	—	$	—	$	9,233	$	9,233


	Fair Value Measurements as of December 31, 2023 Using:
(in thousands)	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents—money market funds and U.S. Treasury bills	$	76,856	$	4,985	$	—	$	81,841
Marketable securities—U.S. Treasury notes, U.S. Treasury bills, and federal government agency notes	—		15,000		—		15,000
	$	76,856	$	19,985	$	—	$	96,841
Liabilities:
Embedded derivative liability	$	—	$	—	$	10	$	10
Class C warrant liability	—		—		15,683		15,683
	$	—	$	—	$	15,693	$	15,693

All marketable securities are classified as short-term investments as all are due within one year and include investments in U.S. Treasury notes, U.S. Treasury bills and federal government agency notes. The amortized cost of each investment, individually and in aggregate, approximates fair value. The Company evaluated each marketable security for impairment that is other-than-temporary and concluded that no marketable security was impaired as of June 30, 2024.

The Company’s cash equivalents consisted of money market funds invested in U.S. Treasury securities and direct investments in U.S. Treasury securities. The money market funds were valued based on quoted prices in active markets for identical assets, which represents a Level 1 measurement. U.S. Treasury securities were valued by using inputs observable in active markets for similar securities, which represents a Level 2 measurement in the fair value hierarchy.

The following table provides amortized cost, unrealized gains and losses and the carrying amount of available-for-sale debt marketable securities as of June 30, 2024:


(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Treasury securities	$	2,210	$	—	$	4	$	2,206
Federal Government agency securities	19,368		—		38		19,330
Total available-for-sale debt securities	$	21,578	$	—	$	42	$	21,536

The following table provides a roll-forward of the aggregate fair values financial instruments for which fair values are determined using Level 3 inputs:


(in thousands)	Embedded Derivative Liability		Class C Warrant Liability		Total
Balance as of December 31, 2023	$	10	$	15,683	$	15,693

Change in fair value	—		(6,460)		(6,460)

Balance as of June 30, 2024	$	10	$	9,223	$	9,233

Valuation of Embedded Derivative Liability— The fair value of the embedded derivative liability recognized in connection with the Company’s loan agreement with Hercules (see Note 10), which is associated with additional fees due to Hercules upon events of default, was determined based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The fair value of this embedded derivative liability, which is reported within other non-current liabilities on the consolidated balance sheets, is estimated by the Company at each reporting date based, in part, on the results of third-party valuations, which were prepared based on a discounted cash flow model that considered the timing and probability of occurrence of a redemption upon an event of default, the potential amount of prepayment fees or contingent interest upon an event of default and the Company’s risk-adjusted discount rate of 17%.

Class C Warrant Liability— In December 2022, the Company issued Class C Warrants for the purchase of shares of its common stock in a public offering. The Class C Warrants are accounted for as a liability on the consolidated balance sheet and are adjusted to fair value at period end through “other income (expense)” on the condensed consolidated statements of operations and comprehensive loss.

The Company calculated the fair value of the Class C Warrants using the Black-Scholes option pricing model, which represents a Level 3 measurement within the fair value hierarchy, with the following inputs:


	June 30, 2024		December 31, 2023
Common stock price	$0.58		$0.84
Risk-free interest rate	4.4	%	3.9	%
Expected term (in years)	3.4		3.9
Expected volatility	100.5	%	96.2	%
Expected dividend yield	—	%	—	%

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Insider Trading Arrangements

3 Months Ended

6 Months Ended

Jun. 30, 2024

Trading Arrangements, by Individual

Material Terms of Trading Arrangement

During the three months ended June 30, 2024, the Company’s six section 16 officers adopted written plan for the purchase or sale of Company securities intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). These plans were adopted on June 28, 2024, and are subject to a 90-day “cool off” period before any trades may be conducted under such plans.

Name

Titles

Action Taken

Type of Trading

Nature of Trading

Expiration Date

Aggregate Number of Securities

Christophe Arbet-Engels

Chief Medical Officer

Adoption (June 28, 2024)

Rule 10b5-1 trading arrangement

Sale

8/1/2025

(i) 572,917 shares of common stock subject to employee stock options and (ii) Indeterminable (2).

Mark Baldry

Chief Commercial Officer

Adoption (June 28, 2024)

Rule 10b5-1 trading arrangement

Sale

10/1/2025

Indeterminable (1)

Mary DiBiase

Chief Operating Officer

Adoption (June 28, 2024)

Rule 10b5-1 trading arrangement

Sale

10/1/2025

Indeterminable (1)

Adam Mostafa

Chief Financial Officer

Adoption (June 28, 2024)

Rule 10b5-1 trading arrangement

Sale

10/1/2025

Indeterminable (2)

Paula Ragan

President and Chief Executive Officer

Adoption (June 28, 2024)

Rule 10b5-1 trading arrangement

Sale

10/1/2025

(i) 313,794 shares of common stock subject to long, restricted and control stock and (ii) Indeterminable (1)

Arthur Taveras

Chief Scientific Officer

Adoption (June 28, 2024)

Rule 10b5-1 trading arrangement

Sale

10/1/2025

Indeterminable (1)

(1) The number of shares that will be sold in accordance with this trading arrangement is indeterminable at the time of the filing of this Quarterly Report on Form 10-Q for the period ended June 30, 2024. Upon vesting of PRSUs, a sell-to-cover trade may occur or the Company may withhold shares in order to satisfy any applicable tax withholding obligations on behalf of the employee. The number of shares sold in the sell-to-cover will vary based on the market price of the Company’s common stock at the time of settlement.

(2) The number of shares that will be sold in accordance with this trading arrangement is indeterminable at the time of the filing of this Quarterly Report on Form 10-Q for the period ended June 30, 2024. Upon vesting of PRSUs, a sell-to-cover trade may occur or the Company may withhold shares in order to satisfy any applicable tax withholding obligations on behalf of the employee. The number of shares sold in the sell-to-cover will vary based on the market price of the Company’s common stock at the time of settlement. Any remaining shares held by the seller after the sell-to-cover may be sold pursuant to the terms of this trading arrangement.

Non-Rule 10b5-1 Arrangement Adopted

false

Rule 10b5-1 Arrangement Terminated

false

Non-Rule 10b5-1 Arrangement Terminated

false

Christophe Arbet-Engels [Member]

Trading Arrangements, by Individual

Name

Christophe Arbet-Engels

Title

Chief Medical Officer

Rule 10b5-1 Arrangement Adopted

true

June 28, 2024

399 days

572,917

Trading Arrangements, by Individual

Name

Mark Baldry

Title

Chief Commercial Officer

Rule 10b5-1 Arrangement Adopted

true

Adoption Date

June 28, 2024

Arrangement Duration

460 days

Mary DiBiase [Member]

Trading Arrangements, by Individual

Name

Mary DiBiase

Title

Chief Operating Officer

Rule 10b5-1 Arrangement Adopted

true

Adoption Date

June 28, 2024

Arrangement Duration

460 days

Adam Mostafa [Member]

Trading Arrangements, by Individual

Name

Adam Mostafa

Title

Chief Financial Officer

Rule 10b5-1 Arrangement Adopted

true

Adoption Date

June 28, 2024

Arrangement Duration

460 days

Paula Ragan [Member]

Trading Arrangements, by Individual

Name

Paula Ragan

Title

President and Chief Executive Officer

Rule 10b5-1 Arrangement Adopted

true

June 28, 2024

460 days

313,794

Trading Arrangements, by Individual

Name

Arthur Taveras

Title

Chief Scientific Officer

Rule 10b5-1 Arrangement Adopted

true

Adoption Date

June 28, 2024

Arrangement Duration

460 days

Accrued Expenses (Tables)

6 Months Ended

Jun. 30, 2024

Payables and Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses consisted of the following:


(in thousands)	June 30, 2024		December 31, 2023
Accrued employee compensation and benefits	$	7,175	8,195
Accrued external research and development expenses	5,439		2,804
Accrued royalty and milestone payments	3,037		—
Accrued professional fees	2,538		1,195
Accrued revenue reserves	130		—
Other	1,425		622
	$	19,744	$	12,816

License, and Funding Agreements - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)
Collaboration License And Funding Arrangements [Line Items]
Other income, net	$ 144,000	$ 202,000	$ 249,000	$ 325,000
Collaborative Arrangement, Rights and Obligations, Maximum Aggregate Milestone Payments, Remaining			3,000,000.0
Collaborative Arrangement, Rights and Obligations, Maximum Aggregate Milestone Payments			5,000,000.0
Research and Development Incentive
Collaboration License And Funding Arrangements [Line Items]
Grant receivable	900,000		900,000
Other income, net			300,000	$ 300,000
Genzyme Agreement
Collaboration License And Funding Arrangements [Line Items]
Milestone Payments			13,000,000
Collaborative Arrangement, Rights and Obligations, Maximum Aggregate Milestone Payments, Per Product	$ 7,000,000		$ 7,000,000
Genzyme Agreement \| 6% Net Sales
Collaboration License And Funding Arrangements [Line Items]
Revenue, Performance Obligation, Percentage of Net Sale	0.06		0.06
Revenue from Collaborative Arrangement, Excluding Revenue from Contract with Customer			$ 150,000,000
Genzyme Agreement \| 10% Net Sales
Collaboration License And Funding Arrangements [Line Items]
Revenue, Performance Obligation, Percentage of Net Sale	0.10		0.10
Genzyme Agreement \| 10% Net Sales \| Minimum
Collaboration License And Funding Arrangements [Line Items]
Revenue from Collaborative Arrangement, Excluding Revenue from Contract with Customer			$ 150,000,000
Genzyme Agreement \| 10% Net Sales \| Maximum
Collaboration License And Funding Arrangements [Line Items]
Revenue from Collaborative Arrangement, Excluding Revenue from Contract with Customer			$ 300,000,000
Genzyme Agreement \| 12% Net Sales
Collaboration License And Funding Arrangements [Line Items]
Revenue, Performance Obligation, Percentage of Net Sale	0.12		0.12
Revenue from Collaborative Arrangement, Excluding Revenue from Contract with Customer			$ 300,000,000

Accrued Expenses

6 Months Ended

Jun. 30, 2024

Payables and Accruals [Abstract]

Accrued Expenses

ACCRUED EXPENSES

Accrued expenses consisted of the following:


(in thousands)	June 30, 2024		December 31, 2023
Accrued employee compensation and benefits	$	7,175	8,195
Accrued external research and development expenses	5,439		2,804
Accrued royalty and milestone payments	3,037		—
Accrued professional fees	2,538		1,195
Accrued revenue reserves	130		—
Other	1,425		622
	$	19,744	$	12,816

Long-Term Debt - Summary of Long Term Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Debt Disclosure [Abstract]
Principal amount of long-term debt	$ 75,000	$ 55,000
Debt discount, net of accretion	(759)	(917)
Cumulative accretion of end of term payments	789	487
Long-term debt	$ 75,030	$ 54,570

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

+ References + Details

Income Taxes	6 Months Ended
Income Taxes	Jun. 30, 2024
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES The income tax provision recorded for the three and six months ended June 30, 2024 and 2023 is primarily related to the Company’s Austrian subsidiary and its Security Corporation subsidiary that holds a portion of its investment portfolio. The Company did not record a U.S. federal or state provision or benefit for income taxes in its consolidated statement of operations and comprehensive income (loss) for the three and six month periods ended June 30, 2024 and 2023. For the six months ended June 30, 2024, the Company generated net income and ordinary income. However, as the Company is projecting an ordinary loss before income taxes for the full year and as the Company has a full valuation allowance on its net operating loss carryforwards, the Company has not recorded a U.S. federal or state income tax expense or benefit for the three month and six months ended June 30, 2024. The Company continues to maintain a valuation allowance against all remaining net deferred tax assets. The Company believes that it is more likely than not that it will not realize a future tax benefit of these attributes as the Company expects to continue to generate operating losses. Ultimate realization of any deferred tax asset is dependent on the Company’s ability to generate sufficient future taxable income in the appropriate tax jurisdiction before the expiration of carryforward periods, if any. The Company will continue to monitor the valuation allowance assessment throughout the year.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 270
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482526/740-270-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

Inventory (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Inventory Disclosure [Abstract]
Raw materials	$ 612	$ 0
Finished goods	219	0
Inventory	$ 831	$ 0

Gain on Sale of Non-Financial Asset (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Discontinued Operations and Disposal Groups [Abstract]
Gain (Loss) on Disposition of Assets	$ 105,000	$ 0	$ 105,000	$ 0

Property and Equipment, Net (Tables)

6 Months Ended

Jun. 30, 2024

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment

Property and equipment, net consisted of the following:


(in thousands)	June 30, 2024		December 31, 2023
Leasehold improvements	$	228	$	228
Furniture and fixtures	1,381		1,301
Computer equipment	263		160
Software	24		24
Lab equipment	651		651
	2,547		2,364
Less: Accumulated depreciation and amortization	(1,739)		(1,619)
	$	808	$	745

Revenue - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Revenue - Narrative (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 700		$ 700
Product revenue, net	$ 563	$ 0	$ 563	$ 0

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 924
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Section 50
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-Subparagraph (a)
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
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-Subparagraph (b)
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-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 40
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-40

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
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-Subparagraph (a)
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-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-41

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-4

+ Details

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

+ Details

Fair Value of Financial Assets and Liabilities (Tables)

3 Months Ended

6 Months Ended

Jun. 30, 2024

Fair Value Disclosures [Abstract]

Schedule of Assets and Liabilities Measured at Fair Value


	Fair Value Measurements as of June 30, 2024 Using:
(in thousands)	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents—money market funds and U.S. Treasury bills	$	106,171	$	23,845	$	—	$	130,016
Marketable securities— U.S. Treasury notes, U.S. Treasury bills, and federal government agency notes	—		21,536		—		21,536
	$	106,171	$	45,381	$	—	$	151,552
Liabilities:
Embedded derivative liability	$	—	$	—	$	10	$	10
Class C warrant liability	—		—		9,223		9,223
	$	—	$	—	$	9,233	$	9,233


	Fair Value Measurements as of December 31, 2023 Using:
(in thousands)	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents—money market funds and U.S. Treasury bills	$	76,856	$	4,985	$	—	$	81,841
Marketable securities—U.S. Treasury notes, U.S. Treasury bills, and federal government agency notes	—		15,000		—		15,000
	$	76,856	$	19,985	$	—	$	96,841
Liabilities:
Embedded derivative liability	$	—	$	—	$	10	$	10
Class C warrant liability	—		—		15,683		15,683
	$	—	$	—	$	15,693	$	15,693

Debt Securities, Available-for-Sale


(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Treasury securities	$	2,210	$	—	$	4	$	2,206
Federal Government agency securities	19,368		—		38		19,330
Total available-for-sale debt securities	$	21,578	$	—	$	42	$	21,536

Summary of Aggregate Fair Values of Warrant Liability and Derivative Liability

The following table provides a roll-forward of the aggregate fair values financial instruments for which fair values are determined using Level 3 inputs:


(in thousands)	Embedded Derivative Liability		Class C Warrant Liability		Total
Balance as of December 31, 2023	$	10	$	15,683	$	15,693

Change in fair value	—		(6,460)		(6,460)

Balance as of June 30, 2024	$	10	$	9,223	$	9,233

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions


	June 30, 2024		December 31, 2023
Common stock price	$0.58		$0.84
Risk-free interest rate	4.4	%	3.9	%
Expected term (in years)	3.4		3.9
Expected volatility	100.5	%	96.2	%
Expected dividend yield	—	%	—	%

- Definition

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

+ Details

Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2024

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Significant Accounting Policies—The Company’s significant accounting policies are disclosed in the audited consolidated financial statements and the notes thereto in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 filed with the SEC on March 21, 2024. Since the date of those consolidated financial statements, there have been no material changes to the Company’s significant accounting policies other than as follows:

Revenue Recognition— The Company records revenue using the guidance of ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”), as amended. Upon the approval by the FDA of the sales and marketing of the Company’s lead product candidate, revenue related to its sale and distribution is accounted for under ASC 606. The Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the Company determines it expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (1) identify the customer and contract with the customer; (2) identify the performance obligations in the contract; (3) determine the transaction

price, adjusted for variable consideration resulting from potential returns, rebates, discounts, and down-stream charges; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when the Company satisfies its performance obligations, which is upon shipment of the finished product to the customer.

The Company currently sells its product to one U.S. customer, which is a specialty pharmacy. The specialty pharmacy dispenses the Company’s drug product to patients in the U.S.. The Company records revenue when the specialty pharmacy obtains control over the promised good, which occurs at a point in time, typically upon delivery to the specialty pharmacy. The Company has concluded that it provides one performance obligation in its contract with its customer: the delivery of drug product that has been approved for sale and distribution by the applicable regulatory authority.

As part of the accounting for its contract arrangements, the Company makes significant judgments, primarily related to the estimation of the amount of variable consideration to include in the transaction price upon delivery of the Company’s drug product. The variable consideration includes estimates for discounts, product returns, rebates that will be due to U.S. federal and state payors, such as Medicaid, based on agreements that the Company has with these payors who provide medical insurance to the end patient, and estimated co-pay assistance payments for patients who enroll in the Company’s patient assistance program. These variable payments are considered a reduction of the Company’s transaction price with its customer and must be estimated at the time the Company’s product is delivered to the customer. The Company determines the amount of variable consideration by using the expected value method. Net revenue recognized for each period is the amount for which, based on management’s estimate, it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates these estimates based on new information and actual operational trends and if necessary, adjusts these variable consideration estimates. Any such adjustments are recorded on a cumulative catch-up basis in the period of the adjustment.

Inventory— Prior to receiving approval from the FDA in April 2024 to sell XOLREMDI (mavorixafor) in the United States, the Company expensed all costs incurred related to the manufacture of mavorixafor as research and development expense due to the inherent risks associated with the development of a drug candidate, the uncertainty about the regulatory approval process and the lack of history for the Company in obtaining of regulatory approval of drug candidates. The Company has capitalized inventory-related costs that were incurred subsequent to FDA approval, such as the bottling, labelling, and packaging of drug product, and the acquisition of raw materials for the production of drug substance to be used in commercial drug product. In connection therewith, the Company values inventories at the lower of cost or estimated net realizable value. The Company determines the cost of inventories on a first-in, first-out (“FIFO”) basis. Raw materials and work in process include all inventory costs prior to packaging, and labelling, including raw materials and the active pharmaceutical ingredient used in the drug product. Finished goods include packaged and labelled drug products designated for commercial distribution. Clinical drug supplies are expensed to research and development. Raw materials and work in process that may be used for either research and development or commercial sale are classified as inventory until the material is consumed or otherwise allocated for research and development. If the material may only be used for research and development, it is expensed as research and development.

Cost of Revenue— Cost of revenue consists of drug product costs, amortization of intangible assets associated with license agreements, accrued royalty costs and capitalized internal direct and overhead costs associated with the manufacturing, lot release and distribution of XOLREMDI. Cost of revenue may also include costs related to excess or obsolete inventory adjustment charges and abnormal manufacturing costs.

Intangible Assets, Net— Definite-lived intangible assets related to capitalized milestones under license agreements are amortized on a straight-line basis, which aligns with the pattern over which the economic benefit of the intangible assets are consumed, over their remaining useful lives, which are estimated to be the remaining patent life. If the Company’s estimate of the product’s useful life is shorter than the remaining patent life, then a shorter period is used. Amortization expense is recorded as a component of cost of revenue on the consolidated statements of operations and comprehensive income (loss).

Restricted Cash


(in thousands)	As of June 30, 2024		As of December 31, 2023

Letter of credit security: Waltham lease	$	—	$	250
Letter of credit security: Vienna Austria lease	205		211
Letter of credit security: Boston lease	573		571
Total restricted cash	$	778	$	1,032
Restricted cash included in prepaid expenses and other current assets	$	—	$	250
Restricted cash included in other assets	$	778	$	782

In connection with the Company’s lease agreements for its facilities in Massachusetts and Austria, the Company maintains letters of credit, which are secured by restricted cash, for the benefit of the respective landlord. The Company’s Waltham lease agreement expired in December 2023; however, the letter of credit was in place as of December 31, 2023 pending the landlord’s completion of its lease expiration procedures. The letter of credit was released in first quarter ended March 31, 2024. In accordance with the Company’s Hercules Loan Agreement and as further described in Note 10, the Company at all times must maintain a minimum level of cash of $20.0 million in an account or accounts in which Hercules has a first priority security interest as further described in Note 10.


(in thousands)	June 30, 2024		December 31, 2023
Cash and cash equivalents	$	147,218	$	99,216
Restricted cash, current (included within prepaid expenses and other current assets)	—		250
Restricted cash, non-current	778		782
Total cash, cash equivalents and restricted cash	$	147,996	$	100,248

Goodwill—Goodwill is tested for impairment at the reporting unit level annually in the fourth quarter, or more frequently when

events or changes in circumstances indicate that the asset might be impaired. Examples of such events or circumstances include,

but are not limited to, a significant adverse change in legal or business climate, an adverse regulatory action or unanticipated

competition. The Company has determined that it operates in a single operating segment and has a single reporting unit.

The Company assesses qualitative factors to determine whether the existence of events or circumstances would indicate that it

is more likely than not that the fair value of the reporting unit is less than its carrying amount. If after assessing the totality of

events or circumstances, the Company were to determine that it is more likely than not that the fair value of the reporting unit is

less than its carrying amount, then the Company would perform an interim quantitative impairment test, whereby the Company

compares the fair value of the reporting unit to its carrying value. If the fair value of the reporting unit exceeds the carrying

value of its net assets, goodwill is not impaired, and no further testing is required. If the fair value of the reporting unit is less

than its carrying value, the Company measures the amount of impairment loss, if any, as the excess of the carrying value over

the fair value of the reporting unit. There were no triggering events during the three months ended June 30, 2024 that

necessitated an interim impairment test of goodwill.

Recently Adopted Accounting Standards

In November 2023, the Financial Accounting Standards Board (“FASB”) issued ASU 2023-07, Segment Reporting (Topic 326) Improvements to Reportable Segment Disclosures (“ASU 2023-07”). Among other disclosure enhancements, ASU 2023-07 requires that entities with one reportable segment, such as the Company, disclose general information for its reportable segment, such as the title and position of the individual identified as the Chief Operating Decision Maker (“CODM”), which for the Company is the Chief Executive Officer, the types of products and services provided by the reportable segment, the measure of profit or loss reviewed by the CODM to evaluate performance of the reportable segment and other financial results such as interest income, interest expense, and depreciation associated with the reportable segment. The amendments in ASU 2023-07 will become effective for the Company in its consolidated financial statements as of and for the three years ending December 31, 2024 and must be adopted retrospectively. Although the Company continues to evaluate the potential impact of

ASU 2023-07, the Company does not believe that the adoption of ASU 2023-07 will have a material impact on its consolidated financial statement when adopted.

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740) Improvements to Income Tax Disclosures (“ASU 2023-09”). The amendments in ASU 2023-09 require that entities on an annual basis disclose specific categories in the income tax rate reconciliation and provide additional information for reconciling items if the effect of those reconciling items that exceed a certain threshold. ASU 2023-09 will also require more disaggregated disclosures related to income taxes paid. The amendments in ASU 2023-09 will become effective for the Company in its December 31, 2024 consolidated financial statements. Although the Company continues to evaluate the impact of ASU 2023-09, the Company expects that these amendments will require further disclosures in the tax footnote of its annual consolidated financial statements and will not have a material impact on its consolidated financial states when adopted.

Long-Term Debt (Tables)

6 Months Ended

Jun. 30, 2024

Debt Disclosure [Abstract]

Summary of Long Term Debt

Long-term debt consisted of the following:


(in thousands)	June 30, 2024		December 31, 2023
Principal amount of long-term debt	$	75,000	$	55,000
Debt discount, net of accretion	(759)		(917)
Cumulative accretion of end of term payments	789		487
Long-term debt	$	75,030	$	54,570

Interest Income and Interest Expense Disclosure

The Company recognized interest expense under the Hercules Loan Agreement as follows:


(in thousands)	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023		2024		2023
Total interest expense	$	2,176	$	1,148	$	4,049	$	2,257
Non-cash interest expense	$	207	$	219	$	461	$	444

Schedule of Future Principal Payments and the Final Payments Due

As of June 30, 2024, future principal and accrued end-of-term payments of $75.8 million under the Hercules Loan Agreement are due on July 1, 2027.


(in thousands),
Year Ending December 31,	Total
2024	$	—
2025	—
2026	—

2027	75,789
Long-term debt	$	75,789

Leases

6 Months Ended

Jun. 30, 2024

Leases [Abstract]

Leases

LEASES

The Company has lease agreements for its facility in Boston, Massachusetts, which is the Company’s principal executive office and Vienna, Austria, which is the Company’s research and development center. There are no restrictions or financial covenants associated with any of the lease agreements. The Company has an operating lease for approximately 1,200 square meters of laboratory and office space in Vienna, Austria (“Vienna Lease”), that commenced in February 2021 for a term of 7 years. The annual base rent for the Vienna Lease is approximately $282 thousand. The Company also leases approximately 28,000 square feet of office space in Boston, Massachusetts (“Boston Lease”), which serves as the Company’s headquarters. Base rental

payments are approximately $1.1 million annually, plus certain operating expenses. The term of the Boston Lease will continue until November 2026, unless earlier terminated. The Company has the right to renew the Boston Lease for an additional five years at the then prevailing effective market rental rate. The Company is required to maintain a security deposit in the form of a letter of credit for $0.6 million for the benefit of the landlord.

As the Company’s leases do not provide an implicit rate, the Company estimated the incremental borrowing rate in calculating the present value of the lease payments. The Company utilizes its incremental borrowing rates, which are the rates incurred to borrow on a collateralized basis over a similar term and amount equal to the lease payments in a similar economic environment.

The components of lease expense for the three and six months ended June 30, 2024 and 2023 were as follows:


(dollars in thousands)	Three Months Ended June 30,						Six Months Ended June 30,
Lease Cost	2024			2023			2024			2023
Fixed operating lease cost	$	489		$	521		$	978		$	1,043

Total lease expense	$	489		$	521		$	978		$	1,043
Other information

Operating cash outflows from operating leases	$	343		$	345		$	687		$	691
Sublease income	$	—		$	48		$	—		$	97
Weighted-average remaining lease term—operating leases	2.7			3.6			2.7			3.6
Weighted-average discount rate—operating leases	11.5		%	11.4		%	11.5		%	11.4		%

Maturities of lease liabilities due under lease agreements that have commenced as of June 30, 2024 are as follows (in thousands):


Maturity of lease liabilities	Operating Leases
2024 (remainder of the year)	$	688
2025	1,402
2026	1,332
2027	280
2028	47

Total lease payments	3,749
Less: interest	(551)
Total operating lease liabilities as of June 30, 2024	$	3,198

Commitment and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Contingencies And Commitments [Line Items]
Loss Contingency Accrual	$ 2.7
Indemnification Agreements
Contingencies And Commitments [Line Items]
Accrued liabilities	$ 0.0	$ 0.0

Long-Term Debt - Summary of Interest Expense (Details) - Hercules Loan Agreement - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Debt Instrument [Line Items]
Interest expense, debt	$ 2,176	$ 1,148	$ 4,049	$ 2,257
Amortization of debt discount	$ 207	$ 219	$ 461	$ 444

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Fair Value of Financial Assets and Liabilities - Aggregate Fair Values Financial Instruments (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2024 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 15,693
Change in fair value	(6,460)
Ending balance	9,233
Embedded Derivative Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	10
Change in fair value	0
Ending balance	10
Class C Warrant Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	15,683
Change in fair value	(6,460)
Ending balance	$ 9,223

Summary of Significant Accounting Policies - Schedule of Compensating Balance Arrangements (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Cash and Cash Equivalents [Line Items]
Restricted Cash	$ 778	$ 1,032
Restricted cash, current (included within prepaid expenses and other current assets)	0	250
Total restricted cash	778	782
Letter of Credit \| Waltham Lease
Cash and Cash Equivalents [Line Items]
Restricted Cash	0	250
Letter of Credit \| Vienna Austria Lease
Cash and Cash Equivalents [Line Items]
Restricted Cash	205	211
Letter of Credit \| Allston Lease Agreement
Cash and Cash Equivalents [Line Items]
Restricted Cash	$ 573	$ 571

Revenue (Tables)

6 Months Ended

Jun. 30, 2024

Revenue from Contract with Customer [Abstract]

Schedule of Product Reserve Accounts

The following table summarizes the activity in each of the product reserve accounts for the six months ended June 30, 2024.


(in thousands)	Rebates and Discounts		Co-Pay Assistance		Product Returns		Total
Beginning balance at December 31, 2023	$	—	$	—	$	—	$	—
Provision related to revenue in the three and six month period ended June 30, 2024	44		35		92		171
Credits and payments made during the period	(21)		(20)		—		(41)
Balance as of June 30, 2024	$	23	$	15	$	92	$	130

Schedule of Accounts, Notes, Loans and Financing Receivable

The following table provides a rollforward of accounts receivable for the six months ended June 30, 2024. There was no activity in accounts receivable in the six months ended June 30, 2023.


(in thousands)	Accounts Receivable
Beginning balance at December 31, 2023	$	—
Increase in accounts receivable for drug product sales	713
Decrease in accounts receivable for cash collections	(713)
Balance as of June 30, 2024	$	—

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Product revenue, net	$ 563	$ 0	$ 563	$ 0
Costs and operating expenses:
Cost of revenue	268	0	268	0
Research and development	20,914	15,601	40,768	37,664
Selling, general and administrative	13,278	10,204	30,713	17,445
Gain on sale of non-financial asset (Note 17)	(105,000)	0	(105,000)	0
Total operating (income) expense	(70,540)	25,805	(33,251)	55,109
Loss from operations	71,103	(25,805)	33,814	(55,109)
Other income (expense), net:
Interest income	1,565	914	2,631	1,749
Interest expense	(2,176)	(1,148)	(4,050)	(2,257)
Other income, net	144	202	249	325
Total other income (expense), net	19,748	(29,892)	5,290	(24,604)
Income (loss) before provision for income taxes	90,851	(55,697)	39,104	(79,713)
Provision for income taxes	18	15	37	19
Net income (loss)	$ 90,833	$ (55,712)	$ 39,067	$ (79,732)
Net loss per share attributable to common stockholders—basic	$ 0.45	$ (0.33)	$ 0.20	$ (0.51)
Net loss per share attributable to common stockholders—diluted	$ 0.45	$ (0.33)	$ 0.19	$ (0.51)
Weighted average shares of common stock outstanding—basic	200,440,473	168,737,764	200,216,035	157,415,524
Weighted average shares of common stock outstanding—diluted	200,801,311	168,737,764	200,455,883	157,415,524
Supplemental Income Statement Elements [Abstract]
Change in unrealized loss on marketable debt securities	$ (6)	$ 0	$ (42)	$ 0
Comprehensive income (loss)	90,827	(55,712)	39,025	(79,732)
Warrant Liability
Other income (expense), net:
Change in fair value of warrant liability	$ 20,215	$ (29,860)	$ 6,460	$ (24,421)

Revenue - Accounts Receivable (Details) $ in Thousands	6 Months Ended
Revenue - Accounts Receivable (Details) $ in Thousands	Jun. 30, 2024 USD ($)
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance at December 31, 2023	$ 0
Increase in accounts receivable for drug product sales	713
Decrease in accounts receivable for cash collections	(713)
Balance as of June 30, 2024	$ 0

Leases - Schedule of Maturities of Lease Liabilities (Detail) $ in Thousands	Jun. 30, 2024 USD ($)
Leases [Abstract]
2024 (remainder of the year)	$ 688
2025	1,402
2026	1,332
2027	280
2028	47
Total lease payments	3,749
Less: interest	(551)
Operating lease, liability	$ 3,198

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Property, Plant and Equipment [Abstract]
Depreciation	$ 131	$ 253
Amortization	$ 131	$ 253

Fair Value of Financial Assets and Liabilities - Fair Value Assumptions (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		6 Months Ended
	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate (in percentage)			4.40%	4.00%	4.20%	3.80%
Expected term (in years)			6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days	6 years
Expected volatility (in percentage)			96.50%	93.40%	96.00%	92.10%
Expected dividend yield (in percentage)			0.00%	0.00%	0.00%	0.00%
Fair value of warrant liability	$ 9,233	$ 15,693	$ 9,233		$ 9,233
Class C Warrant Liability
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Price (in dollars per share)	$ 0.58	$ 0.84	$ 0.58		$ 0.58
Risk-free interest rate (in percentage)	4.40%	3.90%
Expected term (in years)	3 years 4 months 24 days	3 years 10 months 24 days
Expected volatility (in percentage)	100.50%	96.20%
Expected dividend yield (in percentage)	0.00%	0.00%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Net Loss per Share - Schedule of Anti-dilutive Securities Excluded from Computation of Diluted Net Loss per Share Attributable to Common Stockholders (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share (in shares)	94,085,908	89,688,877	94,085,908	89,688,877
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share (in shares)	9,906,298	3,583,186	9,906,298	3,583,186
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share (in shares)	7,800,805	5,859,232	7,800,805	5,859,232
Class C Warrant Liability
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share (in shares)	76,378,805	80,246,459	76,378,805	80,246,459