Acumen Pharmaceuticals (ABOS) 10-Q 13 Nov 23 2023 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2023	Nov. 09, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity File Number	001-40551
Entity Registrant Name	Acumen Pharmaceuticals, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	36-4108129
Entity Address, Address Line One	427 Park St.
Entity Address, City or Town	Charlottesville
Entity Address, State or Province	VA
Entity Address, Postal Zip Code	22902
City Area Code	434
Local Phone Number	297-1000
Title of 12(b) Security	Common stock, par value $0.0001 per share
Trading Symbol	ABOS
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	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		57,910,461
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Entity Central Index Key	0001576885
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 94,917	$ 130,101
Marketable securities, short-term	120,517	47,504
Prepaid expenses and other current assets	3,164	2,724
Total current assets	218,598	180,329
Marketable securities, long-term	67,270	15,837
Restricted cash	189	0
Property and equipment, net	123	165
Right-of-use asset	2	105
Other assets	189	151
Total assets	286,371	196,587
Current liabilities
Accounts payable	1,362	1,640
Accrued clinical trial expenses	1,566	2,717
Accrued expenses and other current liabilities	3,168	3,350
Operating lease liability	2	105
Total current liabilities	6,098	7,812
Total liabilities	6,098	7,812
Commitments and contingencies (Note 6)
Stockholders’ equity
Preferred stock, $0.0001 par value; 10,000,000 shares authorized and no shares issued and outstanding as of September 30, 2023 and December 31, 2022	0	0
Common stock, $0.0001 par value; 300,000,000 shares authorized as of September 30, 2023 and December 31, 2022; 57,910,461 and 41,025,062 shares issued and outstanding as of September 30, 2023 and December 31, 2022, respectively	6	4
Additional paid-in capital	487,077	359,949
Accumulated deficit	(206,301)	(170,427)
Accumulated other comprehensive loss	(509)	(751)
Total stockholders’ equity	280,273	188,775
Total liabilities and stockholders’ equity	$ 286,371	$ 196,587

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	57,910,461	41,025,062
Common stock, shares outstanding (in shares)	57,910,461	41,025,062

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating expenses
Research and development	$ 11,179	$ 8,309	$ 29,025	$ 21,615
General and administrative	4,860	3,062	13,627	9,374
Total operating expenses	16,039	11,371	42,652	30,989
Loss from operations	(16,039)	(11,371)	(42,652)	(30,989)
Other income (expense)
Interest income, net	3,124	663	6,840	1,000
Other expense, net	(42)	(2)	(62)	(1)
Total other income	3,082	661	6,778	999
Net loss	(12,957)	(10,710)	(35,874)	(29,990)
Other comprehensive gain (loss)
Unrealized gain (loss) on marketable securities	137	0	242	(734)
Comprehensive loss	$ (12,820)	$ (10,710)	$ (35,632)	$ (30,724)
Net loss per common share, basic (in dollars per share)	$ (0.24)	$ (0.26)	$ (0.79)	$ (0.74)
Net loss per common share, diluted (in dollars per share)	$ (0.24)	$ (0.26)	$ (0.79)	$ (0.74)
Weighted-average shares outstanding, basic (in shares)	54,229,630	40,502,860	45,474,953	40,491,181
Weighted-average shares outstanding diluted (in shares)	54,229,630	40,502,860	45,474,953	40,491,181

Condensed Statements of Changes

Condensed Statements of Changes in Stockholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Dec. 31, 2021		40,473,270
Beginning balance at Dec. 31, 2021	$ 225,183	$ 4	$ 352,981	$ (127,571)	$ (231)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised for cash (in shares)		25,108
Stock options exercised for cash	19		19
Unrealized gain (loss) on marketable securities	(734)				(734)
Cashless stock options exercise (in shares)		4,746
Stock-based compensation	2,173		2,173
Net loss	(29,990)			(29,990)
Ending balance (in shares) at Sep. 30, 2022		40,503,124
Ending balance at Sep. 30, 2022	196,651	$ 4	355,173	(157,561)	(965)
Beginning balance (in shares) at Jun. 30, 2022		40,501,258
Beginning balance at Jun. 30, 2022	206,519	$ 4	354,331	(146,851)	(965)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised for cash (in shares)		1,866
Stock options exercised for cash	2		2
Unrealized gain (loss) on marketable securities	0
Stock-based compensation	840		840
Net loss	(10,710)			(10,710)
Ending balance (in shares) at Sep. 30, 2022		40,503,124
Ending balance at Sep. 30, 2022	$ 196,651	$ 4	355,173	(157,561)	(965)
Beginning balance (in shares) at Dec. 31, 2022	41,025,062	41,025,062
Beginning balance at Dec. 31, 2022	$ 188,775	$ 4	359,949	(170,427)	(751)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for cash, net of issuance costs of $7,706 (in shares)		16,774,193
Issuance of common stock for cash, net of issuance costs of $7,706	$ 122,294	$ 2	122,292
Stock options exercised for cash (in shares)	111,206	111,206
Stock options exercised for cash	$ 325		325
Unrealized gain (loss) on marketable securities	242				242
Stock-based compensation	4,511		4,511
Net loss	$ (35,874)			(35,874)
Ending balance (in shares) at Sep. 30, 2023	57,910,461	57,910,461
Ending balance at Sep. 30, 2023	$ 280,273	$ 6	487,077	(206,301)	(509)
Beginning balance (in shares) at Jun. 30, 2023		41,025,062
Beginning balance at Jun. 30, 2023	168,874	$ 4	362,860	(193,344)	(646)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for cash, net of issuance costs of $7,706 (in shares)		16,774,193
Issuance of common stock for cash, net of issuance costs of $7,706	122,294	$ 2	122,292
Stock options exercised for cash (in shares)		111,206
Stock options exercised for cash	325		325
Unrealized gain (loss) on marketable securities	137				137
Stock-based compensation	1,600		1,600
Net loss	$ (12,957)			(12,957)
Ending balance (in shares) at Sep. 30, 2023	57,910,461	57,910,461
Ending balance at Sep. 30, 2023	$ 280,273	$ 6	$ 487,077	$ (206,301)	$ (509)

Condensed Statements of Chang_2

Condensed Statements of Changes in Stockholders’ Equity (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Common Stock
Payments of stock issuance costs	$ 7,706	$ 7,706

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities
Net loss	$ (35,874)	$ (29,990)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	42	20
Stock-based compensation expense	4,511	2,173
Amortization of premiums and accretion of discounts on marketable securities, net	(1,344)	575
Amortization of right-of-use asset	103	100
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(436)	2,058
Other assets	(38)	(78)
Accounts payable	(278)	996
Accrued clinical trial expenses	(1,151)	1,358
Operating lease liability	(103)	(100)
Accrued expenses and other current liabilities	(182)	(1,062)
Net cash used in operating activities	(34,750)	(23,950)
Cash flows from investing activities
Purchases of marketable securities	(178,857)	(12,129)
Proceeds from maturities and sales of marketable securities	55,997	71,860
Proceeds from sale of property and equipment	3	0
Purchases of property and equipment	(7)	(126)
Net cash provided by (used in) investing activities	(122,864)	59,605
Cash flows from financing activities
Proceeds from issuance of common stock, net of issuance costs	122,294	0
Proceeds from exercise of stock options	325	19
Payments for deferred offering costs	0	(296)
Net cash provided by (used in) financing activities	122,619	(277)
Net change in cash and cash equivalents and restricted cash	(34,995)	35,378
Cash and cash equivalents and restricted cash at the beginning of the period	130,101	122,162
Cash and cash equivalents and restricted cash at the end of the period	95,106	157,540
Supplemental disclosure of noncash investing and financing activities
Proceeds from sale of property and equipment in other current assets	4	0
Right-of-use assets obtained in exchange for operating lease liabilities	0	233
Deferred offering costs in accrued expenses and other current liabilities	0	41
Reconciliation of cash, cash equivalents and restricted cash to the condensed balance sheets
Cash and cash equivalents	94,917	157,540
Restricted cash	189	0
Total cash, cash equivalents and restricted cash	$ 95,106	$ 157,540

DESCRIPTION OF ORGANIZATION AND

DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS	DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS Acumen Pharmaceuticals, Inc. (“Acumen” or the “Company”) was incorporated in 1996 in the state of Delaware. Acumen is a clinical-stage biopharmaceutical company developing a novel disease-modifying approach to target what the Company believes to be a key underlying cause of Alzheimer’s disease (“AD”). Alzheimer’s disease is a progressive neurodegenerative disease of the brain that leads to loss of memory and cognitive functions and ultimately results in death. The Company’s scientific founders pioneered research on soluble amyloid-beta oligomers (“AßOs”), which are globular assemblies of the amyloid-beta (“Aß”) peptide that are distinct from Aß monomers and amyloid plaques. Based on decades of research and supporting evidence, AßOs have gained increasing scientific acceptance as primary toxins involved in the initiation and propagation of AD pathology. The Company is currently focused on advancing a targeted immunotherapy drug candidate, ACU193, through clinical development following Phase 1 results in “early AD” patients (patients with mild cognitive impairment or mild dementia due to Alzheimer’s pathology) that were announced in July 2023. ACU193 is a recombinant humanized immunoglobulin gamma 2 (“IgG2”) monoclonal antibody (“mAb”) that was designed to selectively target AßOs, has demonstrated functional and protective effects in in vitro assays, and has demonstrated in vivo safety and pharmacologic activity in multiple animal species, including transgenic mouse models for AD. The Company is subject to the uncertainty of whether the Company’s intellectual property will develop into successful commercial products. Public Offering On July 21, 2023, the Company issued 16,774,193 shares of its common stock, $0.0001 par value per share (“Common Stock”), in a public offering (the “Offering”) at a price to the public of $7.75 per share. The aggregate net proceeds from the Offering, after underwriting discounts and commissions and other offering expenses, were $122.3 million. Liquidity and Capital Resources The Company has incurred operating losses since inception and expects to continue to incur significant operating losses for the foreseeable future and may never become profitable. As of September 30, 2023 and December 31, 2022, the Company had an accumulated deficit of $206.3 million and $170.4 million, respectively, and working capital of $212.5 million and $172.5 million, respectively. Management believes that the Company has sufficient cash to continue operating activities for beyond 12 months from issuance of these condensed financial statements. Future capital requirements will depend upon many factors, including the timing and extent of spending on research and development and market acceptance of the Company’s products. The Company expects that it will need to obtain additional financing to complete clinical trials and launch and commercialize any product candidates for which it receives regulatory approval. Until such time, if ever, the Company can generate revenue sufficient to achieve profitability, the Company expects to finance its operations through a combination of equity offerings, debt financings, collaborations, strategic alliances and licensing arrangements. There can be no assurance that such financing will be available on terms acceptable to the Company, or at all. To the extent that the Company raises additional capital through the sale of equity or convertible debt securities, the ownership interest of its stockholders will be diluted, and the terms of these securities may include liquidation of other preferences that adversely affect the rights of common stockholders. Debt financing and preferred equity financing, if available, may involve agreements that include covenants limiting or restricting the Company’s ability to take specific actions, such as incurring additional debt, making acquisitions or capital expenditures or declaring dividends. If the Company is unable to maintain sufficient financial resources, its business, financial condition and results of operations will be materially and adversely affected. The Company may be required to delay, limit, reduce or terminate its product discovery and development activities or future commercialization efforts. The Company initiated a Phase 1 clinical trial of ACU193 in the second quarter of 2021, which the Company named “INTERCEPT-AD.” This trial enrolled 65 patients with “early AD.” INTERCEPT-AD was a U.S.-based, multi-center, randomized, double-blind, placebo-controlled clinical trial with overlapping single ascending dose and multiple ascending dose cohorts evaluating patients with early AD. Topline results were announced in July 2023. The Company plans to initiate a Phase 2 portion of a Phase 2/3 clinical trial of ACU193 in the first half of 2024.

BASIS OF PRESENTATION, SUMMARY

BASIS OF PRESENTATION, SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
BASIS OF PRESENTATION, SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS	BASIS OF PRESENTATION, SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. In the opinion of management, the unaudited condensed financial statements reflect all adjustments, which include only normal recurring adjustments necessary for the fair statement of the balances and results for the periods presented. Certain information and note disclosures normally included in the Company’s annual financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. These unaudited condensed financial statement results are not necessarily indicative of results to be expected for the full fiscal year or any future period. A description of the Company’s significant accounting policies is included in the Company’s Annual Report. Other than as described below, there have been no material changes in the Company’s significant accounting policies to those previously disclosed in the Company’s Annual Report. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the unaudited condensed financial statements, as well as the reported amounts of expenses during the reporting periods. These estimates and assumptions are based on the Company’s historical experience, and on various other factors that management believes are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities and the recording of expenses that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions. To the extent there are material differences between the estimates and actual results, the Company’s future results of operations will be affected. Reclassifications Certain prior year amounts have been reclassified for consistency with the current period presentation. Accrued clinical trial expenses are presented as a separate line on the statements of cash flows, whereas these accrued expenses were previously included in accrued expenses and other current liabilities. This reclassification had no effect on the reported results of operations. Cash and Cash Equivalents and Restricted Cash The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. All of the Company’s cash equivalents have liquid markets and high credit ratings. The Company had $94.6 million and $129.1 million in cash equivalents as of September 30, 2023 and December 31, 2022, respectively. Restricted cash consists of deposited cash collateral for the Company’s corporate credit card program. Stock-based Compensation The Company expenses stock-based compensation to employees, non-employees and board members over the requisite service period based on the estimated grant date fair value of the awards and actual forfeitures. The Company estimates the fair value of stock option grants using the Black-Scholes option pricing model, which requires the use of a number of complex assumptions including the fair value of the Common Stock, expected volatility, risk-free interest rate, expected dividends, and the expected term of the option. The fair value of restricted stock units is the closing market price of the Common Stock on the date of the grant. The assumptions used in calculating the fair value of stock-based awards represent management’s best estimates and involve inherent uncertainties and the application of management’s judgment. Stock- based awards with graded-vesting schedules are recognized on a straight-line basis over the requisite service period for the last separately vesting portion of the award. All stock-based compensation costs are recorded in research and development expense or general and administrative expense in the statements of operations and comprehensive loss based upon the respective employee’s or non-employee’s role within the Company. Forfeitures are recorded as they occur. See also Note 8. Stock-based Compensation below. Recently Adopted Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which was codified with its subsequent amendments as Accounting Standards Codification (“ASC”) 326. ASC 326 seeks to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments, including trade receivables, and other commitments to extend credit held by a reporting entity at each reporting date. The amendments require an entity to replace the incurred loss impairment methodology in current U.S. GAAP with a methodology that reflects current expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The updated guidance was effective for the Company on January 1, 2023. The Company’s marketable securities portfolio consists entirely of available-for-sale debt securities and, as such, the adoption of this guidance did not have a material impact on its financial statements and disclosures upon adoption, but it did require the Company to provide additional disclosures related to its available-for-sale debt securities in a continuous unrealized loss position.

MARKETABLE SECURITIES

MARKETABLE SECURITIES	9 Months Ended
	Sep. 30, 2023
Marketable Securities [Abstract]
MARKETABLE SECURITIES	MARKETABLE SECURITIES The Company’s marketable securities consisted of the following (in thousands): September 30, 2023 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale securities, short-term Corporate debt securities $ 88,459 $ 14 $ (239) $ 88,234 Government and agency - U.S. 32,302 2 (21) 32,283 Total available-for-sale securities, short-term 120,761 16 (260) 120,517 Available-for-sale securities, long-term Corporate debt securities 52,605 7 (258) 52,354 Government and agency - U.S. 14,934 — (18) 14,916 Total available-for-sale securities, long-term 67,539 7 (276) 67,270 Total available-for-sale securities $ 188,300 $ 23 $ (536) $ 187,787 December 31, 2022 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale securities, short-term Corporate debt securities $ 30,174 $ — $ (249) $ 29,925 Asset-backed securities 3,006 — (102) 2,904 Government and agency - U.S. 15,032 — (357) 14,675 Total available-for-sale securities, short-term 48,212 — (708) 47,504 Available-for-sale securities, long-term Corporate debt securities 15,880 — (43) 15,837 Total available-for-sale securities, long-term 15,880 — (43) 15,837 Total available-for-sale securities $ 64,092 $ — $ (751) $ 63,341 The following tables summarize the amount of unrealized losses, defined as the amount by which the amortized cost exceeds fair value, and the related fair value of available-for-sale marketable securities with unrealized losses, which have been segregated into two categories: those that have been in a continuous unrealized loss position for less than 12 months and those that have been in a continuous unrealized loss position for 12 or more months. September 30, 2023 Less than 12 Months Greater than 12 Months Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Corporate debt securities $ 119,250 $ (497) $ — $ — $ 119,250 $ (497) Government and agency - U.S. 27,393 (39) — — 27,393 (39) Total $ 146,643 $ (536) $ — $ — $ 146,643 $ (536) December 31, 2022 Less than 12 Months Greater than 12 Months Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Corporate debt securities $ 29,515 $ (58) $ 16,247 $ (234) $ 45,762 $ (292) Asset-backed securities — — 2,904 (102) 2,904 (102) Government and agency - U.S. 3,026 (7) 11,649 (350) 14,675 (357) Total $ 32,541 $ (65) $ 30,800 $ (686) $ 63,341 $ (751) As of September 30, 2023, the Company’s available-for-sale securities classified as short-term mature in one year or less and the Company’s available-for-sale securities classified as long-term mature within less than two years . As noted in the table above, none of the Company’s available-for-sale marketable securities as of September 30, 2023 have been in an unrealized loss position for more than 12 months. No credit losses were recognized on the Company’s available-for-sale securities during the three and nine months ended September 30, 2023. There were no realized gains or losses for the three and nine months ended September 30, 2023 and 2022

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS The Company’s financial assets and liabilities subject to fair value measurement on a recurring basis and the level of inputs used for such measurements were as follows (in thousands): Fair value measurements at reporting date using Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fair Value at September 30, 2023 Assets included in: Cash and cash equivalents Money market securities $ 64,760 $ — $ — $ 64,760 Government and agency - U.S. — 29,877 — 29,877 Marketable securities Corporate debt securities — 140,588 — 140,588 Government and agency - U.S. — 47,199 — 47,199 Total fair value $ 64,760 $ 217,664 $ — $ 282,424 Fair value measurements at reporting date using Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fair Value at December 31, 2022 Assets included in: Cash and cash equivalents Money market securities $ 129,100 $ — $ — $ 129,100 Marketable securities Corporate debt securities — 45,762 — 45,762 Asset-backed securities — 2,904 — 2,904 Government and agency - U.S. — 14,675 — 14,675 Total fair value $ 129,100 $ 63,341 $ — $ 192,441 The carrying values reported in the Company’s condensed balance sheets for cash (excluding cash equivalents which are recorded at fair value on a recurring basis), accounts payable, accrued clinical trial expenses and accrued expenses and other current liabilities are reasonable estimates of their fair values due to the short-term nature of these items. The fair value of the Company’s money market funds is determined using quoted market prices in active markets for identical assets.

SUPPLEMENTAL FINANCIAL INFORMAT

SUPPLEMENTAL FINANCIAL INFORMATION	9 Months Ended
	Sep. 30, 2023
Supplemental Financial Information [Abstract]
SUPPLEMENTAL FINANCIAL INFORMATION	SUPPLEMENTAL FINANCIAL INFORMATION Prepaid expenses and other current assets consisted of the following (in thousands): September 30, 2023 December 31, 2022 Research and development service agreements $ 1,534 $ 1,077 Prepaid insurance 1,216 1,106 Dues and subscriptions 166 105 Prepaid raw materials 67 199 Other 181 237 Total prepaid expenses and other current assets $ 3,164 $ 2,724 Accrued expenses and other current liabilities consisted of the following (in thousands): September 30, 2023 December 31, 2022 Compensation and other employee liabilities $ 2,054 $ 2,008 Research and development 1,015 1,211 Legal 18 — Other 81 131 Total accrued expenses and other current liabilities $ 3,168 $ 3,350

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES The Company is not a party to any material legal proceedings and is not aware of any pending or threatened claims. From time to time, the Company may be subject to various legal proceedings and claims that arise in the ordinary course of its business activities.In November 2022, the Company entered into a License Agreement (“Agreement”) with Lonza Sales AG (“Lonza”) for a worldwide non-exclusive license to use certain Lonza technology in its research and development and drug manufacturing activities. Under the terms of the Agreement, in consideration of the licenses and consents granted to the Company, the Company is required to make an annual payment to Lonza (i) in Swiss Francs in the low six-digits where the Company manufactures ACU193 and (ii) in Swiss Francs in the mid six-digits per sublicense upon the anniversary date of the Agreement where a third party manufactures ACU193. In addition, if the Company generates Net Sales, as defined in the Agreement, of ACU193, the Company will be obligated to pay Lonza a royalty of low single digits based upon what entity manufactures ACU193 at that time.

STOCKHOLDERS_ EQUITY

STOCKHOLDERS’ EQUITY	9 Months Ended
	Sep. 30, 2023
Stockholders' Equity Note [Abstract]
STOCKHOLDERS’ EQUITY	STOCKHOLDERS’ EQUITY Authorized Shares As of September 30, 2023, the total number of shares of capital stock authorized to be issued per the Company’s Amended and Restated Certificate of Incorporation is 310,000,000, with 10,000,000 shares designated as preferred stock with a par value of $0.0001, and 300,000,000 shares designated as Common Stock. Each share of Common Stock is entitled to one voting right. Shelf Registration and Equity Offerings On July 1, 2022, the Company filed a shelf registration statement on Form S-3 (the “Registration Statement”). Pursuant to the Registration Statement, the Company may offer and sell securities having an aggregate public offering price of up to $200.0 million. In connection with the filing of the Registration Statement, the Company also entered into a sales agreement (the “Sales Agreement”) with BofA Securities, Inc. (“BofA”) and Stifel, Nicolaus & Company, Incorporated (“Stifel”), as sales agents, pursuant to which the Company may issue and sell shares of Common Stock for an aggregate offering price of up to $50.0 million under an at-the-market offering program (the “ATM”), which is included in the $200.0 million of securities that may be offered pursuant to the Registration Statement. On April 23, 2023, the Company entered into an amendment to the Sales Agreement (as amended, the “Amended Sales Agreement”) to add BTIG, LLC (“BTIG”) as a sales agent under the Amended Sales Agreement (BTIG, together with BofA and Stifel, the “Sales Agents”). Pursuant to the Amended Sales Agreement, the Company will pay the Sales Agents a commission rate of up to 3.0% of the gross proceeds from the sale of any shares of Common Stock. The Company is not obligated to make any sales of shares of Common Stock under the ATM. The Company did not sell any shares of its Common Stock under the ATM during the nine months ended September 30, 2023. On July 21, 2023, the Company issued 16,774,193 shares of Common Stock in the Offering for net proceeds of $122.3 million. See Note 1. Description of Organization and Business Operations .

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION 2021 Equity Incentive Plan The 2021 Equity Incentive Plan (the “2021 Plan”), which provides for the grant of incentive stock options to employees, and the grant of nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance awards and other forms of stock awards to employees, directors and consultants, became effective on June 30, 2021. The 2021 Plan is a successor to the Company’s Amended and Restated Stock Performance Plan that was adopted by the Company’s Board of Directors (the “Board”) and stockholders on April 8, 2013 (as amended from time to time, most recently on November 20, 2020, the “2013 Plan”). Following the effectiveness of the 2021 Plan, no further grants may be made under the 2013 Plan; however, any outstanding equity awards granted under the 2013 Plan continue to be governed by the terms of the 2013 Plan. As of September 30, 2023, there were 3,231,274 options outstanding under the 2013 Plan. Initially, the maximum number of shares of Common Stock that may be issued under the 2021 Plan was 7,698,282 shares, which is the sum of (1) 3,550,000 new shares, plus (2) 667,104 shares that remained available for issuance under the Company’s 2013 Plan at the time the 2021 Plan became effective, plus (3) any shares subject to outstanding stock options or other stock awards that were granted under the 2013 Plan that, on or after the 2021 Plan became effective, terminate or expire prior to exercise or settlement, are settled in cash, are forfeited or repurchased because of the failure to vest, or are reacquired or withheld to satisfy a tax withholding obligation or the purchase or exercise price in accordance with the terms of the 2013 Plan. In addition, the number of shares of Common Stock reserved for issuance under the 2021 Plan will automatically increase on January 1 of each calendar year, starting on January 1, 2022 through January 1, 2031, in an amount equal to 5% of the total number of shares of Common Stock outstanding on December 31 of the fiscal year before the date of each automatic increase, or a lesser number of shares determined by the Board prior to the applicable January 1. On January 1, 2023, the Board increased the number of shares of Common Stock reserved for issuance under the 2021 Plan by 2,051,253 shares. The maximum number of shares of Common Stock that may be issued upon the exercise of incentive stock options under the 2021 Plan is 12,000,000. As of September 30, 2023, 11,773,198 shares were authorized for issuance under the 2021 Plan and 3,798,530 shares remained available for issuance under the 2021 Plan. The Company recorded stock-based compensation expense in the following expense categories of its condensed statements of operations for the periods shown (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 General and administrative $ 1,127 $ 563 $ 3,143 $ 1,525 Research and development 473 277 1,368 648 Total stock-based compensation $ 1,600 $ 840 $ 4,511 $ 2,173 Stock Options The Black-Scholes option-pricing model was used to estimate the fair value of stock options granted during the nine months ended September 30, 2023 and 2022 with the following weighted average assumptions: Nine Months Ended September 30, 2023 2022 Risk-free interest rate 3.47% - 4.43% 1.71% - 4.17% Expected term (in years) 5.5 - 6.1 5.8 - 6.1 Expected volatility 90% - 98% 90% Expected dividend yield 0% 0% The weighted average grant date fair value of options granted during the nine months ended September 30, 2023 and 2022, was $4.53 per share and $3.77 per share, respectively. Stock options granted after December 31, 2017 generally vest monthly over a range of 12 to 48 months or vest monthly over a total of 48 months following a one-year cliff and all have a 10-year contractual term. During the nine months ended September 30, 2023, the Company also issued option awards to its Board that vest in full on the first anniversary of the grant date. Stock options granted prior to December 31, 2017 were either fully vested upon grant or generally vested monthly over a range of three The following table reflects summarized stock option activity: Stock Options Weighted Average Exercise Price Weighted Average Remaining Contractual Life (in years) Aggregate Intrinsic Value (in thousands) Outstanding at January 1, 2023 5,610,893 $ 3.36 Granted 1,921,200 $ 5.96 Exercised (111,206) $ 2.92 Forfeited (14,489) $ 2.88 Expired (6,251) $ 8.33 Outstanding at September 30, 2023 7,400,147 $ 4.04 7.9 $ 9,907 Vested and exercisable at September 30, 2023 3,621,345 $ 3.02 7.2 $ 7,432 As of September 30, 2023, total unrecognized compensation costs related to unvested stock option awards was approximately $13.5 million, which the Company expects to recognize over a weighted-average period of approximately 2.4 years. Restricted Stock Units In January 2023, the Company granted a restricted stock unit (“RSU”) award to each of its then current employees. These RSU awards vest in equal annual installments on the first three anniversaries of the grant date. Number of Shares Weighted Average Grant Date Fair Value Unvested as of January 1, 2023 — $ — Granted 328,500 $ 6.11 Unvested at September 30, 2023 328,500 $ 6.11 As of September 30, 2023, total unrecognized compensation costs related to unvested RSUs was approximately $1.5 million, which the Company expects to recognize over a weighted-average period of approximately 2.3 years. Employee Stock Purchase Plan

NET LOSS PER SHARE

NET LOSS PER SHARE	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
NET LOSS PER SHARE	NET LOSS PER SHARE The Company computes net loss per common share using the two-class method required for participating securities. Basic and diluted net loss per share was the same for each period presented as the inclusion of all potential common stock outstanding would have been anti-dilutive. Potentially dilutive securities not included in the calculation of diluted net loss per common share, because to do so would be anti-dilutive, include shares issuable upon the exercise of stock options and unvested RSUs as follows: Nine Months Ended September 30, 2023 2022 Shares issuable upon exercise of stock options 7,400,147 5,655,948 Unvested RSUs 328,500 — Total 7,728,647 5,655,948

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	9 Months Ended
	Sep. 30, 2023
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS On November 5, 2023, the Company entered into a Non-exclusive Collaboration and License Agreement (the “Halozyme License Agreement”) with Halozyme, Inc. (“Halozyme”). Under the terms of the Halozyme License Agreement, Halozyme granted the Company a non-exclusive license to Halozyme’s ENHANZE® drug delivery technology for the development of a subcutaneous formulation of ACU193 (such combination, the “Product”). Halozyme will also be the Company’s exclusive supplier of clinical and commercial supplies of the API for Halozyme’s PH20 product. The Company will make a seven figure upfront payment for the license to Halozyme’s technology. Additionally, the Company will make milestone payments tied to achievement of certain development and commercialization milestone events with respect to the Product, as well as milestone payments based on achievement of certain net sales levels of the Product. The Company will also make single-digit royalty payments based on worldwide net sales of the Product. On November 10, 2023 (the “Closing Date”), the Company entered into a Loan and Security Agreement (the “Loan Agreement”) with the lenders referred to therein (the “Lenders”), K2 HealthVentures LLC (“K2HV”), as administrative agent for the Lenders, and Ankura Trust Company, LLC, as collateral agent for the Lenders. The Loan Agreement provides up to $50.0 million principal in term loans (the “Term Loan”) consisting of a first tranche of $30.0 million funded on the Closing Date and a subsequent second tranche of up to $20.0 million upon the Company’s request, subject to review by the Lenders of certain information from the Company and discretionary approval by the Lenders. The Term Loan matures on November 1, 2027, provided, that the maturity date may be extended to November 1, 2028 if the Company achieves certain other financing milestones. The obligations of the Company under the Loan Agreement are secured by substantially all of the assets of the Company, excluding the Company’s intellectual property. The Term Loan bears a variable interest rate equal to the greater of (i) 9.65% and (ii) the sum of (a) the Prime Rate as reported in the Wall Street Journal plus (b) 1.15%. The Company may prepay, at its option, all, or a portion of the Term Loan then outstanding plus the accrued and unpaid interest on the portion of principal so repaid, subject to a prepayment premium to which the Lenders are entitled and certain notice requirements. The Lenders may elect at any time following the Closing Date and prior to the full repayment of the Term Loan to convert any portion of the principal amount of the term loans then outstanding, up to an aggregate of $2.5 million in principal amount, into shares of the Company’s common stock (the “Conversion Shares”), at a conversion price of $2.53 per share, subject to certain beneficial ownership limitations. In addition, under the Loan Agreement, the Company issued to K2HV a warrant to purchase up to 730,769 shares of the Company’s common stock at an exercise price of $1.95 per share.

BASIS OF PRESENTATION, SUMMAR_2

BASIS OF PRESENTATION, SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS (Policies)	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. In the opinion of management, the unaudited condensed financial statements reflect all adjustments, which include only normal recurring adjustments necessary for the fair statement of the balances and results for the periods presented. Certain information and note disclosures normally included in the Company’s annual financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. These unaudited condensed financial statement results are not necessarily indicative of results to be expected for the full fiscal year or any future period.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the unaudited condensed financial statements, as well as the reported amounts of expenses during the reporting periods. These estimates and assumptions are based on the Company’s historical experience, and on various other factors that management believes are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities and the recording of expenses that are not readily apparent from other sources.
Reclassifications	Reclassifications Certain prior year amounts have been reclassified for consistency with the current period presentation. Accrued clinical trial expenses are presented as a separate line on the statements of cash flows, whereas these accrued expenses were previously included in accrued expenses and other current liabilities. This reclassification had no effect on the reported results of operations.
Cash and Cash Equivalents and Restricted Cash	Cash and Cash Equivalents and Restricted CashThe Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. All of the Company’s cash equivalents have liquid markets and high credit ratings.Restricted cash consists of deposited cash collateral for the Company’s corporate credit card program.
Stock-based Compensation	Stock-based Compensation The Company expenses stock-based compensation to employees, non-employees and board members over the requisite service period based on the estimated grant date fair value of the awards and actual forfeitures. The Company estimates the fair value of stock option grants using the Black-Scholes option pricing model, which requires the use of a number of complex assumptions including the fair value of the Common Stock, expected volatility, risk-free interest rate, expected dividends, and the expected term of the option. The fair value of restricted stock units is the closing market price of the Common Stock on the date of the grant. The assumptions used in calculating the fair value of stock-based awards represent management’s best estimates and involve inherent uncertainties and the application of management’s judgment. Stock-
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which was codified with its subsequent amendments as Accounting Standards Codification (“ASC”) 326. ASC 326 seeks to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments, including trade receivables, and other commitments to extend credit held by a reporting entity at each reporting date. The amendments require an entity to replace the incurred loss impairment methodology in current U.S. GAAP with a methodology that reflects current expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The updated guidance was effective for the Company on January 1, 2023. The Company’s marketable securities portfolio consists entirely of available-for-sale debt securities and, as such, the adoption of this guidance did not have a material impact on its financial statements and disclosures upon adoption, but it did require the Company to provide additional disclosures related to its available-for-sale debt securities in a continuous unrealized loss position.

MARKETABLE SECURITIES (Tables)

MARKETABLE SECURITIES (Tables)	9 Months Ended
	Sep. 30, 2023
Marketable Securities [Abstract]
Summary of Marketable Securities	The Company’s marketable securities consisted of the following (in thousands): September 30, 2023 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale securities, short-term Corporate debt securities $ 88,459 $ 14 $ (239) $ 88,234 Government and agency - U.S. 32,302 2 (21) 32,283 Total available-for-sale securities, short-term 120,761 16 (260) 120,517 Available-for-sale securities, long-term Corporate debt securities 52,605 7 (258) 52,354 Government and agency - U.S. 14,934 — (18) 14,916 Total available-for-sale securities, long-term 67,539 7 (276) 67,270 Total available-for-sale securities $ 188,300 $ 23 $ (536) $ 187,787 December 31, 2022 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale securities, short-term Corporate debt securities $ 30,174 $ — $ (249) $ 29,925 Asset-backed securities 3,006 — (102) 2,904 Government and agency - U.S. 15,032 — (357) 14,675 Total available-for-sale securities, short-term 48,212 — (708) 47,504 Available-for-sale securities, long-term Corporate debt securities 15,880 — (43) 15,837 Total available-for-sale securities, long-term 15,880 — (43) 15,837 Total available-for-sale securities $ 64,092 $ — $ (751) $ 63,341
Summary of Unrealized Losses	The following tables summarize the amount of unrealized losses, defined as the amount by which the amortized cost exceeds fair value, and the related fair value of available-for-sale marketable securities with unrealized losses, which have been segregated into two categories: those that have been in a continuous unrealized loss position for less than 12 months and those that have been in a continuous unrealized loss position for 12 or more months. September 30, 2023 Less than 12 Months Greater than 12 Months Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Corporate debt securities $ 119,250 $ (497) $ — $ — $ 119,250 $ (497) Government and agency - U.S. 27,393 (39) — — 27,393 (39) Total $ 146,643 $ (536) $ — $ — $ 146,643 $ (536) December 31, 2022 Less than 12 Months Greater than 12 Months Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Corporate debt securities $ 29,515 $ (58) $ 16,247 $ (234) $ 45,762 $ (292) Asset-backed securities — — 2,904 (102) 2,904 (102) Government and agency - U.S. 3,026 (7) 11,649 (350) 14,675 (357) Total $ 32,541 $ (65) $ 30,800 $ (686) $ 63,341 $ (751)

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Summary of Fair Value, Assets and Liabilities Measured on Recurring Basis	The Company’s financial assets and liabilities subject to fair value measurement on a recurring basis and the level of inputs used for such measurements were as follows (in thousands): Fair value measurements at reporting date using Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fair Value at September 30, 2023 Assets included in: Cash and cash equivalents Money market securities $ 64,760 $ — $ — $ 64,760 Government and agency - U.S. — 29,877 — 29,877 Marketable securities Corporate debt securities — 140,588 — 140,588 Government and agency - U.S. — 47,199 — 47,199 Total fair value $ 64,760 $ 217,664 $ — $ 282,424 Fair value measurements at reporting date using Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fair Value at December 31, 2022 Assets included in: Cash and cash equivalents Money market securities $ 129,100 $ — $ — $ 129,100 Marketable securities Corporate debt securities — 45,762 — 45,762 Asset-backed securities — 2,904 — 2,904 Government and agency - U.S. — 14,675 — 14,675 Total fair value $ 129,100 $ 63,341 $ — $ 192,441

SUPPLEMENTAL FINANCIAL INFORM_2

SUPPLEMENTAL FINANCIAL INFORMATION (Tables)	9 Months Ended
	Sep. 30, 2023
Supplemental Financial Information [Abstract]
Summary of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following (in thousands): September 30, 2023 December 31, 2022 Research and development service agreements $ 1,534 $ 1,077 Prepaid insurance 1,216 1,106 Dues and subscriptions 166 105 Prepaid raw materials 67 199 Other 181 237 Total prepaid expenses and other current assets $ 3,164 $ 2,724
Summary of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): September 30, 2023 December 31, 2022 Compensation and other employee liabilities $ 2,054 $ 2,008 Research and development 1,015 1,211 Legal 18 — Other 81 131 Total accrued expenses and other current liabilities $ 3,168 $ 3,350

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Summary of Share-Based Compensation Expense Related to Stock Options	The Company recorded stock-based compensation expense in the following expense categories of its condensed statements of operations for the periods shown (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 General and administrative $ 1,127 $ 563 $ 3,143 $ 1,525 Research and development 473 277 1,368 648 Total stock-based compensation $ 1,600 $ 840 $ 4,511 $ 2,173
Summary of Assumptions Used for Valuation of Fair Value of Stock Options	The Black-Scholes option-pricing model was used to estimate the fair value of stock options granted during the nine months ended September 30, 2023 and 2022 with the following weighted average assumptions: Nine Months Ended September 30, 2023 2022 Risk-free interest rate 3.47% - 4.43% 1.71% - 4.17% Expected term (in years) 5.5 - 6.1 5.8 - 6.1 Expected volatility 90% - 98% 90% Expected dividend yield 0% 0%
Summary of Stock Option Activity	The following table reflects summarized stock option activity: Stock Options Weighted Average Exercise Price Weighted Average Remaining Contractual Life (in years) Aggregate Intrinsic Value (in thousands) Outstanding at January 1, 2023 5,610,893 $ 3.36 Granted 1,921,200 $ 5.96 Exercised (111,206) $ 2.92 Forfeited (14,489) $ 2.88 Expired (6,251) $ 8.33 Outstanding at September 30, 2023 7,400,147 $ 4.04 7.9 $ 9,907 Vested and exercisable at September 30, 2023 3,621,345 $ 3.02 7.2 $ 7,432
Summary of Nonvested Restricted Stock Units Activity	Number of Shares Weighted Average Grant Date Fair Value Unvested as of January 1, 2023 — $ — Granted 328,500 $ 6.11 Unvested at September 30, 2023 328,500 $ 6.11

NET LOSS PER SHARE (Tables)

NET LOSS PER SHARE (Tables)	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Summary of Antidilutive Securities Excluded from Computation of Loss Per Share	Potentially dilutive securities not included in the calculation of diluted net loss per common share, because to do so would be anti-dilutive, include shares issuable upon the exercise of stock options and unvested RSUs as follows: Nine Months Ended September 30, 2023 2022 Shares issuable upon exercise of stock options 7,400,147 5,655,948 Unvested RSUs 328,500 — Total 7,728,647 5,655,948

DESCRIPTION OF ORGANIZATION A_2

DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS (Details) $ / shares in Units, $ in Thousands	Jul. 21, 2023 USD ($) $ / shares shares	Sep. 30, 2023 USD ($) patient $ / shares	Dec. 31, 2022 USD ($) $ / shares
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Common stock, par value (in dollars per share) | $ / shares		$ 0.0001	$ 0.0001
Accumulated deficit | $		$ 206,301	$ 170,427
Working capital | $		$ 212,500	$ 172,500
Number of patients enrolled in trail | patient		65
Public Offering
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sale of stock, number of shares issued in transaction (in shares) | shares	16,774,193
Common stock, par value (in dollars per share) | $ / shares	$ 0.0001
Sale of stock, price per share (in dollars per share) | $ / shares	$ 7.75
Sale of stock, consideration received on transaction | $	$ 122,300

BASIS OF PRESENTATION, SUMMAR_3

BASIS OF PRESENTATION, SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Cash equivalents	$ 94.6	$ 129.1

MARKETABLE SECURITIES - Summary

MARKETABLE SECURITIES - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Marketable Securities [Line Items]
Amortized cost, short term	$ 120,761	$ 48,212
Gross unrealized gains, short term	16	0
Gross unrealized losses, short term	(260)	(708)
Fair value, short term	120,517	47,504
Amortized cost, long term	67,539	15,880
Gross unrealized gains, long term	7	0
Gross unrealized losses, long term	(276)	(43)
Fair value, long term	67,270	15,837
Amortized cost, total	188,300	64,092
Gross unrealized gains, total	23	0
Gross unrealized losses, total	(536)	(751)
Fair value, total	187,787	63,341
Corporate debt securities
Marketable Securities [Line Items]
Amortized cost, short term	88,459	30,174
Gross unrealized gains, short term	14	0
Gross unrealized losses, short term	(239)	(249)
Fair value, short term	88,234	29,925
Amortized cost, long term	52,605	15,880
Gross unrealized gains, long term	7	0
Gross unrealized losses, long term	(258)	(43)
Fair value, long term	52,354	15,837
Asset-backed securities
Marketable Securities [Line Items]
Amortized cost, short term		3,006
Gross unrealized gains, short term		0
Gross unrealized losses, short term		(102)
Fair value, short term		2,904
Government and agency - U.S.
Marketable Securities [Line Items]
Amortized cost, short term	32,302	15,032
Gross unrealized gains, short term	2	0
Gross unrealized losses, short term	(21)	(357)
Fair value, short term	32,283	$ 14,675
Amortized cost, long term	14,934
Gross unrealized gains, long term	0
Gross unrealized losses, long term	(18)
Fair value, long term	$ 14,916

MARKETABLE SECURITIES - Summa_2

MARKETABLE SECURITIES - Summary of Unrealized Loss on Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Marketable Securities [Line Items]
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months	$ 146,643	$ 32,541
Debt securities, available-for-sale, Continuous unrealized loss position, less than 12 months, accumulated loss	(536)	(65)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer	0	30,800
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, accumulated loss	0	(686)
Debt securities, available-for-sale, unrealized loss position	146,643	63,341
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(536)	(751)
Corporate debt securities
Marketable Securities [Line Items]
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months	119,250	29,515
Debt securities, available-for-sale, Continuous unrealized loss position, less than 12 months, accumulated loss	(497)	(58)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer	0	16,247
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, accumulated loss	0	(234)
Debt securities, available-for-sale, unrealized loss position	119,250	45,762
Debt securities, available-for-sale, unrealized loss position, accumulated loss	(497)	(292)
Asset-backed securities
Marketable Securities [Line Items]
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months		0
Debt securities, available-for-sale, Continuous unrealized loss position, less than 12 months, accumulated loss		0
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer		2,904
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, accumulated loss		(102)
Debt securities, available-for-sale, unrealized loss position		2,904
Debt securities, available-for-sale, unrealized loss position, accumulated loss		(102)
Government and agency - U.S.
Marketable Securities [Line Items]
Debt securities, available-for-sale, continuous unrealized loss position, less than 12 months	27,393	3,026
Debt securities, available-for-sale, Continuous unrealized loss position, less than 12 months, accumulated loss	(39)	(7)
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer	0	11,649
Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, accumulated loss	0	(350)
Debt securities, available-for-sale, unrealized loss position	27,393	14,675
Debt securities, available-for-sale, unrealized loss position, accumulated loss	$ (39)	$ (357)

MARKETABLE SECURITIES - Additio

MARKETABLE SECURITIES - Additional Information (Details)	9 Months Ended
	Sep. 30, 2023
Marketable Securities [Line Items]
Debt securities, available-for-sale, noncurrent, term (in years)	2 years
Maximum
Marketable Securities [Line Items]
Debt securities, available-for-sale, current, term (in years)	1 year
Minimum
Marketable Securities [Line Items]
Debt securities, available-for-sale, unrealized loss position period (in months)	12 months

FAIR VALUE MEASUREMENTS - Summa

FAIR VALUE MEASUREMENTS - Summary of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Marketable securities
Total fair value	$ 282,424	$ 192,441
Quoted Prices in Active Markets for Identical Assets (Level 1)
Marketable securities
Total fair value	64,760	129,100
Significant Other Observable Inputs (Level 2)
Marketable securities
Total fair value	217,664	63,341
Significant Unobservable Inputs (Level 3)
Marketable securities
Total fair value	0	0
Corporate debt securities
Marketable securities
Marketable securities	140,588	45,762
Corporate debt securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Marketable securities
Marketable securities	0	0
Corporate debt securities | Significant Other Observable Inputs (Level 2)
Marketable securities
Marketable securities	140,588	45,762
Corporate debt securities | Significant Unobservable Inputs (Level 3)
Marketable securities
Marketable securities	0	0
Asset-backed securities
Marketable securities
Marketable securities		2,904
Asset-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Marketable securities
Marketable securities		0
Asset-backed securities | Significant Other Observable Inputs (Level 2)
Marketable securities
Marketable securities		2,904
Asset-backed securities | Significant Unobservable Inputs (Level 3)
Marketable securities
Marketable securities		0
Government and agency - U.S.
Marketable securities
Marketable securities	47,199	14,675
Government and agency - U.S. | Quoted Prices in Active Markets for Identical Assets (Level 1)
Marketable securities
Marketable securities	0	0
Government and agency - U.S. | Significant Other Observable Inputs (Level 2)
Marketable securities
Marketable securities	47,199	14,675
Government and agency - U.S. | Significant Unobservable Inputs (Level 3)
Marketable securities
Marketable securities	0	0
Money market securities
Cash and cash equivalents
Cash and cash equivalents	64,760	129,100
Money market securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Cash and cash equivalents
Cash and cash equivalents	64,760	129,100
Money market securities | Significant Other Observable Inputs (Level 2)
Cash and cash equivalents
Cash and cash equivalents	0	0
Money market securities | Significant Unobservable Inputs (Level 3)
Cash and cash equivalents
Cash and cash equivalents	0	$ 0
Government and agency - U.S.
Cash and cash equivalents
Cash and cash equivalents	29,877
Government and agency - U.S. | Quoted Prices in Active Markets for Identical Assets (Level 1)
Cash and cash equivalents
Cash and cash equivalents	0
Government and agency - U.S. | Significant Other Observable Inputs (Level 2)
Cash and cash equivalents
Cash and cash equivalents	29,877
Government and agency - U.S. | Significant Unobservable Inputs (Level 3)
Cash and cash equivalents
Cash and cash equivalents	$ 0

SUPPLEMENTAL FINANCIAL INFORM_3

SUPPLEMENTAL FINANCIAL INFORMATION - Summary of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Supplemental Financial Information [Abstract]
Research and development service agreements	$ 1,534	$ 1,077
Prepaid insurance	1,216	1,106
Dues and subscriptions	166	105
Prepaid raw materials	67	199
Other	181	237
Total prepaid expenses and other current assets	$ 3,164	$ 2,724

SUPPLEMENTAL FINANCIAL INFORM_4

SUPPLEMENTAL FINANCIAL INFORMATION - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Supplemental Financial Information [Abstract]
Compensation and other employee liabilities	$ 2,054	$ 2,008
Research and development	1,015	1,211
Legal	18	0
Other	81	131
Total accrued expenses and other current liabilities	$ 3,168	$ 3,350

STOCKHOLDERS_ EQUITY (Details)

STOCKHOLDERS’ EQUITY (Details) $ / shares in Units, $ in Millions		9 Months Ended
	Jul. 21, 2023 USD ($) shares	Sep. 30, 2023 votingRight $ / shares shares	Dec. 31, 2022 $ / shares shares	Jul. 01, 2022 USD ($)
Class of Stock [Line Items]
Common stock and preferred stock, shares authorized (in shares)		310,000,000
Preferred stock, shares authorized (in shares)		10,000,000	10,000,000
Preferred stock, par value (in dollars per share) | $ / shares		$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)		300,000,000	300,000,000
Common stock, number of voting rights | votingRight		1
Sale of stock, commission rate to sales agents (as a percent)				3%
Registration Statement
Class of Stock [Line Items]
Sale of stock, maximum authorized amount | $				$ 200
At The Market Offering
Class of Stock [Line Items]
Sale of stock, maximum authorized amount | $				$ 50
Sale of stock, number of shares issued in transaction (in shares)		0
Public Offering
Class of Stock [Line Items]
Sale of stock, number of shares issued in transaction (in shares)	16,774,193
Sale of stock, consideration received on transaction | $	$ 122.3

STOCK-BASED COMPENSATION - Addi

STOCK-BASED COMPENSATION - Additional Information (Details) $ / shares in Units, $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2023 USD ($) anniversary $ / shares shares	Sep. 30, 2022 $ / shares	Dec. 31, 2022 shares	Jan. 01, 2023 shares	Jun. 30, 2021 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options outstanding (in shares)	7,400,147		5,610,893
Weighted average grant date fair value of options granted (in dollars per share) | $ / shares	$ 4.53	$ 3.77
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0%	0%
Option, cost not yet recognized, amount | $	$ 13.5
Weighted average period of recognition (in years)	2 years 4 months 24 days
Stock Options | Granted after December 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in months)	48 months
Cliff period (in years)	1 year
Contractual term (in years)	10 years
Stock Options | Granted prior to December 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term (in years)	10 years
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period of recognition (in years)	2 years 3 months 18 days
Number of anniversaries for vesting | anniversary	3
Non option, cost not yet recognized, amount | $	$ 1.5
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding stock maximum (as a percent)	1%
Common stock, capital shares reserved for future issuance (in shares)				410,251	375,000
Number of shares authorized (in shares)	1,189,983
Shares of common stock outstanding maximum (in shares)	800,000
Shares issued in period (in shares)	0
Minimum | Stock Options | Granted after December 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in months)	12 months
Minimum | Stock Options | Granted prior to December 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in months)	3 months
Maximum | Stock Options | Granted after December 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in months)	48 months
Maximum | Stock Options | Granted prior to December 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in months)	24 months
2013 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options outstanding (in shares)	3,231,274
2013 Equity Incentive Plan | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant (in shares)					667,104
2021 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance (in shares)				2,051,253
Maximum threshold common stock issuable on exercise of incentive stock options (in shares)	12,000,000
2021 Equity Incentive Plan | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant (in shares)	3,798,530				7,698,282
Outstanding stock maximum (as a percent)			5%
Number of shares authorized (in shares)	11,773,198
2021 Equity Incentive Plan | Common Stock, New Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant (in shares)					3,550,000

STOCK-BASED COMPENSATION - Summ

STOCK-BASED COMPENSATION - Summary of Share-Based Compensation Expense Related to Stock Options (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 1,600	$ 840	$ 4,511	$ 2,173
General and administrative
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	1,127	563	3,143	1,525
Research and development
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 473	$ 277	$ 1,368	$ 648

STOCK-BASED COMPENSATION - Su_2

STOCK-BASED COMPENSATION - Summary of Assumptions Used for Valuation of Fair Value of Stock (Details) - Stock Options	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Risk-free interest rate, minimum	3.47%	1.71%
Risk-free interest rate, maximum	4.43%	4.17%
Expected volatility, minimum	90%
Expected volatility, maximum	98%
Expected volatility		90%
Expected dividend yield	0%	0%
Minimum
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Expected term (in years)	5 years 6 months	5 years 9 months 18 days
Maximum
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days

STOCK-BASED COMPENSATION - Su_3

STOCK-BASED COMPENSATION - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2023
Stock Options
Beginning balance (in shares)	5,610,893
Granted (in shares)	1,921,200
Exercised (in shares)	(111,206)
Forfeited (in shares)	(14,489)
Expired (in shares)	(6,251)
Ending balance (in shares)	7,400,147
Vested and exercisable (in shares)	3,621,345
Weighted Average Exercise Price
Beginning balance (in dollars per share)	$ 3.36
Granted (in dollars per share)	5.96
Exercised (in dollars per share)	2.92
Forfeited (in dollars per share)	2.88
Expired (in dollars per share)	8.33
Ending balance (in dollars per share)	4.04
Vested and exercisable (in dollars per share)	$ 3.02
Weighted Average Remaining Contractual Life (in years)
Outstanding balance (in years)	7 years 10 months 24 days
Vested and exercisable (in years)	7 years 2 months 12 days
Ending balance, aggregate intrinsic value	$ 9,907
Vested and exercisable, aggregate intrinsic value	$ 7,432

STOCK-BASED COMPENSATION - Su_4

STOCK-BASED COMPENSATION - Summary of Restricted Stock Units Activity (Details) - RSUs	9 Months Ended
	Sep. 30, 2023 $ / shares shares
Number of Shares
Unvested beginning balance (in shares) | shares	0
Granted (in shares) | shares	328,500
Unvested ending balance (in shares) | shares	328,500
Weighted Average Grant Date Fair Value
Unvested beginning balance (in dollars per share) | $ / shares	$ 0
Granted (in dollars per share) | $ / shares	6.11
Unvested ending balance (in dollars per share) | $ / shares	$ 6.11

NET LOSS PER SHARE (Details)

NET LOSS PER SHARE (Details) - shares	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	7,728,647	5,655,948
Shares issuable upon exercise of stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	7,400,147	5,655,948
Unvested RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	328,500	0

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - Subsequent Event - K2 Health Ventures LLC	Nov. 10, 2023 USD ($) $ / shares shares
Secured Debt
Subsequent Event [Line Items]
Variable interest rate	9.65%
Secured Debt | Prime Rate
Subsequent Event [Line Items]
Variable interest rate	1.15%
Term Loan Credit Agreement | Warrant
Subsequent Event [Line Items]
Warrant purchase (in shares) | shares	730,769
Exercise price (in dollars per share) | $ / shares	$ 1.95
Term Loan Credit Agreement | Secured Debt
Subsequent Event [Line Items]
Borrowing capacity	$ 50,000,000
Conversion, if-converted amount	$ 2,500,000
Conversion price (in dollars per share) | $ / shares	$ 2.53
Term Loan Credit Agreement, First Tranche | Secured Debt
Subsequent Event [Line Items]
Borrowing capacity	$ 30,000,000
Term Loan Credit Agreement, Second Tranche | Secured Debt
Subsequent Event [Line Items]
Borrowing capacity	$ 20,000,000