0001193125-21-247879 | 10-Q | XBRL Viewer | Acumen Pharmaceuticals INC

Stock-Based Compensation

6 Months Ended

Jun. 30, 2021

Share-based Payment Arrangement [Abstract]

NOTE 6. STOCK-BASED COMPENSATION

2013 Stock Performance Plan

On April 8, 2013, the Board and stockholders adopted the Company’s Amended and Restated Stock Performance Plan (as amended from time to time, most recently on November 20, 2020, the “2013 Plan”). The 2013 Plan provided for the grant of incentive stock options, nonstatutory stock options, issuance of shares of restricted stock and other equity awards to the Company’s employees, officers, directors, consultants and advisors. All outstanding awards issued under the 2013 Plan remain subject to the terms of the 2013 Plan. As of June 30, 2021, the aggregate number of shares authorized for issuance under the 2013 Plan totaled 4,179,202 and there were 483,681 shares available for future grants.

Stock Options

The Black-Scholes option-pricing model was used to estimate the fair value of stock options granted during the six months ended June 30, 2021 with the following weighted average assumptions:


Risk-free interest rate		0.4% - 0.5%
Expected term in years		5.3 - 6.3
Expected volatility		90%
Expected dividend yield		0%

The fair value of the Company’s common stock underlying the stock options has historically been determined by the Board with assistance from management and, occasionally with input from an independent third-party valuation firm. For the year ended December 31, 2020, management engaged an independent third-party valuation firm to provide an estimate of the fair value of its common stock. The fair value of common stock was determined considering a number of objective and subjective factors, including valuations of comparable companies, sales of convertible preferred stock, operating and financial performance, the lack of liquidity of the Company’s common stock and the general and industry-specific economic outlook.

As of June 30, 2021 and December 31, 2020, management estimated the fair value of a share of common stock to be $16.00 and

$0.83

, respectively. The fair value as of June 30, 2021 was based upon the per share offering price of the Company’s common stock to the public in its IPO which closed on July 6, 2021. As of December 31, 2020, the Company derived the fair value of its common stock with the assistance of an independent third-party valuation firm utilizing the following assumptions:


Risk-free interest rate			0.13%
Expected time to liquidity event in years			2.0
Expected volatility			90%
Expected dividend yield			0%

The stock options granted after December 31, 2017 vest monthly over 24 or 36 months and have a

ten-year

contractual term. Stock options granted prior to December 31, 2017 were either fully vested upon grant or generally vested monthly over a range of three to 24 months and have a

ten-year

term. The Company is a private company as of June 30, 2021 and lacks company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies. Due to the lack of historical exercise history, the expected term of the Company’s stock options has been determined using the “simplified” method for awards. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is zero based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future.

The weighted average grant date fair value of options granted during the six months ended June 30, 2021 was $1.34 per share. There were no options granted during the six months ended June 30, 2020

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 December 31, 2020		1,001,517	$	1.13
Options granted		2,663,084		2.21

Outstanding at June 30, 2021		3,664,601	$	1.92		8.9	$	51,625

Vested and exercisable at June 30, 2021		872,961	$	1.19		7.3	$	12,941

As of June 30, 2021, total unrecognized compensation costs related to unvested stock option awards granted was approximately

3.4

million, which the Company expects to recognize over a weighted-average period of approximately

3.3

years

The Company recorded stock-based compensation expense related to stock options in the following expense categories of its condensed statements of operations for the periods shown:


	Three Months Ended June 30,				Six Months Ended June 30,
	2021		2020		2021		2020
General and administrative	$	79	$	26	$	159	$	52
Research and development		47		13		94		26

Total stock-based compensation	$	127	$	38	$	253	$	77

Commitments and Contingencies (Tables)

6 Months Ended

Jun. 30, 2021

Commitments and Contingencies Disclosure [Abstract]

Summary of Future Minimum Lease Payments

At June 30, 2021, future minimum lease payments under lease agreements (including short-term leases) associated with our operations were as follows (in thousands):


Year ended December 31, 2021 (remaining 6 months)	$	77
Year ended December 31, 2022		153
Year ended December 31, 2023		102

Total	$	332

Net Loss Per Share (Tables)

6 Months Ended

Jun. 30, 2021

Earnings Per Share [Abstract]

Summary of Dilutive Securities Not Included in the Diluted Net Loss Per Common Share

The table below provides potentially dilutive securities not included in the calculation of the diluted net loss per common share because to do so would be anti-dilutive:


	Six Months Ended June 30,
	2021		2020
Shares issuable upon conversion of Series A Preferred Stock		477,297		477,297
Shares issuable upon conversion of Series A-1 Preferred Stock		7,985,305		7,537,879
Shares issuable upon conversion of Series B Preferred Stock		19,770,070		—
Shares issuable upon exercise of stock options		3,664,601		1,004,898
Shares issuable upon exercise of common stock warrants		248,247		385,693
Shares issuable upon exercise of preferred stock warrant		—		447,426

Total		32,145,520		9,853,193

Condensed Statement of Changes in Convertible Preferred Stock and Stockholders' Deficit (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021
Series B Convertible Preferred Stock [Member]
Stock issuance Costs	$ 16	$ 16

Basis of Presentation, Summary of Significant Accounting Policies and Recent Accounting Pronouncements

6 Months Ended

Jun. 30, 2021

Accounting Policies [Abstract]

Basis of Presentation, Summary of Significant Accounting Policies and Recent Accounting Pronouncements

NOTE 2. BASIS OF PRESENTATION, SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS

Basis of Presentation

The accompanying condensed financial statements have been prepared in accordance with Generally Accepted Accounting Principles in the United States of America (“U.S. GAAP”) for interim financial information and 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 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 condensed financial statement results are not necessarily indicative of results to be expected for the full fiscal year or any future period.

Emerging Growth Company

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”), or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s condensed financial statements upon adoption. Under the Jumpstart Our Business Startups Act of 2012, as amended, the Company meets the definition of an emerging growth company and has elected the extended transition period for complying with new or revised accounting standards, which delays the adoption of these accounting standards until they would apply to private companies.

Use of Estimates

The preparation of condensed 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 condensed financial statements and the reported amounts of expenses during the reporting period. These estimates and assumptions are based on current facts and historical experience, as well as other pertinent industry and regulatory authority information, including the potential future effects of

COVID-19,

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 materially and adversely from these estimates. To the extent there are material differences between the estimates and actual results, the Company’s future results of operations will be affected.

Cash and Cash Equivalents

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. The Company’s cash equivalents consist of funds held in a money market account. The Company had

36.8

million in cash equivalents as of

both

June

30, 2021 and December 31,

2020.

Concentrations of Credit Risk

Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash and cash equivalents. Periodically, the Company may maintain deposits in financial institutions in excess of government insured limits. Management believes that the Company is not exposed to significant credit risk as the Company’s deposits are held at financial institutions that management believes to be of high credit quality.

The Company has not experienced any losses on these deposits.

Fair Value of Financial Instruments

The Company’s financial assets and liabilities are accounted for in accordance with Accounting Standards Codification (“ASC”) 820,

Fair Value Measurements and Disclosure

which defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value hierarchy requires an entity to maximize the use of observable inputs when measuring fair value and classifies those inputs into three levels:

Level 1— Observable inputs, such as quoted prices in active markets for identical assets or liabilities.

Level 2—Inputs other than Level 1 inputs that are either directly or indirectly observable, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the instrument’s anticipated life.

Level 3—Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions.

To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair values requires more judgement. Accordingly, the degree of judgement exercised by management in determining fair value is greatest for instruments categorized as Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement.

The following tables present the Company’s fair value hierarchy for its money market securities, preferred stock tranche rights liability and preferred stock warrant liability measured at fair value on a recurring basis (in thousands):


	Fair value measurements at reporting date using						Fair Value at June 30, 2021
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value at June 30, 2021
Assets included in:
Cash and cash equivalents
Money market securities	$	36,766	$	—	$	—	$	36,766

Total fair value	$	36,766	$	—	$	—	$	36,766


	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, 2020
Assets included in:
Cash and cash equivalents
Money market securities	$	36,758	$	—	$	—	$	36,758

Total fair value	$	36,758	$	—	$	—	$	36,758

Liabilities included in:
Preferred stock tranche rights liability	$	—	$	—	$	5,033	$	5,033
Preferred stock warrant liability		—		—		380		380

Total fair value	$	—	$	—	$	5,413	$	5,413

The carrying values reported in the Company’s condensed balance sheets for cash and cash equivalents, accounts payable, and accrued expenses are reasonable estimates of their fair values due to the short-term nature of these items.

Refer to Note 4 for further information about the Level 3 rollforward of activity and Level 3 inputs.

Grant Receivable

Grant receivable consists of research expenses reimbursable under a grant from the National Institute of Health (“NIH”). The Company carries its grant receivable at the unreimbursed amount. On a periodic basis, the Company evaluates its grant receivable to determine whether an allowance is required. The allowance is management’s best estimate of probable losses. Management determined that no allowance was necessary as of

June 30, 2021 and December 31, 2020.

Convertible Preferred Stock

The Company records shares of convertible preferred stock at their respective fair values on the dates of issuance, net of issuance costs. The Company has applied the guidance in ASC

480-10-S99-3A,

SEC Staff Announcement: Classification and Measurement of Redeemable Securities

and has therefore classified the Series A, Series

A-1

and Series B convertible preferred stock as mezzanine equity. The convertible preferred stock is recorded outside of stockholders’ deficit because, in the event of certain deemed liquidation events considered not solely within the Company’s control, such as a merger, acquisition and sale of all or substantially all of the Company’s assets (a “Deemed Liquidation Event”), the convertible preferred stock will become redeemable at the option of the holders. In the event of a change of control of the Company, proceeds received from the sale of such shares will be distributed in accordance with the corresponding liquidation preferences. The Company did not adjust the carrying values of the convertible preferred stock to the deemed liquidation values of such shares since a liquidation event was not probable at any of the reporting dates. Subsequent adjustments to increase or decrease the carrying values to the ultimate liquidation values will be made only if and when it becomes probable that such a liquidation event will occur.

Preferred Stock Tranche Rights Liability

The Company determined that its obligation to issue, and the Company’s investors’ right to purchase, additional shares of Series B convertible preferred stock pursuant to the Milestone Closing (see Note 1 and Note 4) represented a freestanding financial instrument (the “tranche liability”). The tranche liability was initially recorded at fair value. The proceeds from the sale of the convertible preferred stock were first allocated to the fair value of the tranche liability with the remaining proceeds from the sale of the convertible preferred stock allocated to the Series B convertible preferred stock. The tranche liability was remeasured at each reporting period and upon the exercise of the obligation, with gains and losses arising from subsequent changes in its fair value recognized in other income and expense in the condensed statements of operations. As discussed above in Note 1, the Milestone Closing occurred on June 17, 2021 and, as a result, the remaining value of the tranche liability was reclassified to convertible preferred stock on the condensed balance sheet.

Preferred Stock Warrant Liability

The Company accounted for the warrant to purchase Series

A-1

convertible preferred stock as a liability as this warrant was a freestanding financial instrument that required the Company to transfer assets upon exercise. The warrant liability was initially recorded at fair value. The warrant liability was remeasured at each reporting period and upon the exercise of the applicable warrant, with gains and losses arising from subsequent changes in its fair value recognized in other income and expense in the condensed statements of operations. The warrant was exercised on June 22, 2021 and the remaining value of the warrant liability was reclassified to convertible preferred stock on the condensed balance sheet.

Common Stock Warrants

The Company assesses whether warrants issued require accounting as derivatives. The Company determined that the warrants were (1) indexed to the Company’s own stock and (2) classified in stockholders’ equity in accordance with FASB ASC Topic 815,

Derivatives and Hedging

. As such, the Company has concluded the warrants meet the scope exception for determining whether the instruments require accounting as derivatives and should be classified in stockholders’ equity.

Grant and Other Revenue Recognition

The Company’s NIH grant is not within the scope of ASC 606,

Revenue from Contracts with Customers

(“ASC 606”)

as the grant does not meet the definition of a contract with a customer. The Company has concluded that the grant meets the definition of a contribution and is a

non-reciprocal

transaction, and management has also concluded that Subtopic

958-605,

Not-for-Profit-Entities-Revenue

Recognition

does not apply, as Acumen is a business entity and the grant is with a governmental agency.

In the absence of applicable guidance under U.S. GAAP, the Company’s policy is to recognize grant revenue when the related costs are incurred and the right to payment is realized. Costs incurred are recorded in research and development and general and administrative expenses on the accompanying condensed statements of operations.

The Company believes the recognition of revenue as costs are incurred and amounts become realizable is analogous to the concept of transfer of control of a service over time under ASC 606.

Research and Development Expenses

Research and development expenses primarily consist of consultants and materials, biologic storage, salaries and other personnel-related expenses related to research and development activities and are expensed as incurred. Payments for these activities are based on the terms of the individual agreements, which may differ from the pattern of costs incurred, and are reflected on the condensed balance sheets as prepaid or accrued expenses. The Company records accruals for estimated ongoing research costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the studies, including the phase or completion of events, invoices received and contracted costs.

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 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 each 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 condensed statements of operations based upon the respective employee’s or

non-employee’s

roles within the Company. Forfeitures are recorded as they occur. See also Note 6 below.

Income Taxes

Income taxes are recorded in accordance with ASC 740,

Income Taxes

(“ASC 740”), which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse, and net operating loss (“NOL”) carryforwards and research and development tax credit (“R&D Credit”) carryforwards. Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company has recorded a full valuation allowance to reduce its net deferred income tax assets to zero. In the event the Company were to determine that it would be able to realize some or all its deferred income tax assets in the future, an adjustment to the deferred income tax asset valuation allowance would increase income in the period such determination was made.

The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit would more likely than not be realized assuming examination by the taxing authority. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. The Company has not recorded any accruals related to uncertain tax positions as of June 30, 2021 and December 31, 2020. The Company’s policy is to record interest and penalties, if any, as part of income tax benefit. No interest or penalties were recorded during the six months ended June 30, 2021 and 2020.

Net Loss Per Share of Common Stock

Basic net loss per share of common stock is calculated using the

two-class

method under which earnings are allocated to both common shares and participating securities based on their participation rights. Net loss attributable to common stockholders is not allocated to the convertible preferred stock as the holders of the convertible preferred stock do not have a contractual obligation to share in any losses. Basic net loss per share is calculated by dividing the net loss attributable to common shares by the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share of common stock is computed by dividing the net loss using the weighted-average number of common shares and, if dilutive, potential common shares outstanding during the period. Potential common shares consist of stock options and warrants to purchase common stock (using the treasury stock method), and the conversion of convertible preferred stock and the preferred warrant (using the

if-converted

method). See Note 8 below.

Segment Information

Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one segment.

Recently Issued Accounting Pronouncements

In February 2016, the FASB issued ASU

No. 2016-02,

Leases (Topic 842)

, as amended, with guidance regarding the accounting for and disclosure of leases. This update requires lessees to recognize the liabilities related to all leases, including operating leases, with a term greater than 12 months on the balance sheet. This update also requires lessees and lessors to disclose key information about their leasing transactions. This guidance will become effective for the Company for annual reporting periods beginning after December 15, 2021 and interim periods within fiscal years beginning after December 15, 2022. The adoption of Topic 842 is not expected to have a material impact on the financial statements.

In December 2019, the FASB issued ASU

No. 2019-12,

Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes

(“ASU

2019-12”),

which is intended to simplify various aspects related to accounting for income taxes. ASU

2019-12

removes certain exceptions to the general principles in ASC 740 and also clarifies and amends existing guidance to improve consistent application. This guidance is effective for fiscal years beginning after December 15, 2021, and interim periods within fiscal years beginning after December 15, 2022, with early adoption permitted. The Company is currently evaluating the impact of this standard on its financial statements.

Net Loss Per Share - Summary of Dilutive Securities Not Included in the Diluted Net Loss Per Common Share (Detail) - shares	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion of stock, shares converted	32,145,520	9,853,193
Series A Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion of stock, shares converted	477,297	477,297
Series A1 Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion of stock, shares converted	7,985,305	7,537,879
Series B Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion of stock, shares converted	19,770,070
Exercise of Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion of stock, shares converted	3,664,601	1,004,898
Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion of stock, shares converted	248,247	385,693
Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion of stock, shares converted	0	447,426

Condensed Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Convertible Preferred Stock Shares Authorized	42,066,830	42,066,830
Convertible Preferred Stock Shares Issued	28,232,672	19,877,219
Convertible Preferred Stock Shares Outstanding	28,232,672	19,877,219
Convertible Preferred Stock, Liquidation Preference	$ 94,280	$ 62,984
Common Stock Par Value	$ 0.0001	$ 0.0001
Common Shares Authorized	50,500,000	50,500,000
Common Shares Issued	556,570	419,124
Common Shares Outstanding	556,570	419,124
Series A Convertible Preferred Stock [Member]
Convertible Preferred Stock Par Value	$ 0.0001	$ 0.0001
Convertible Preferred Stock Shares Authorized	711,203	711,203
Convertible Preferred Stock Shares Issued	477,297	477,297
Convertible Preferred Stock Shares Outstanding	477,297	477,297
Convertible Preferred Stock, Liquidation Preference	$ 1,067	$ 1,067
Series A-1 Convertible Preferred Stock [Member]
Convertible Preferred Stock Par Value	$ 0.0001	$ 0.0001
Convertible Preferred Stock Shares Authorized	11,898,177	11,898,177
Convertible Preferred Stock Shares Issued	7,985,305	7,537,879
Convertible Preferred Stock Shares Outstanding	7,985,305	7,537,879
Convertible Preferred Stock, Liquidation Preference	$ 18,097
Series B Convertible Preferred Stock [Member]
Convertible Preferred Stock Par Value	$ 0.0001	$ 0.0001
Convertible Preferred Stock Shares Authorized	29,457,450	29,457,450
Convertible Preferred Stock Shares Issued	19,770,070	11,862,043
Convertible Preferred Stock Shares Outstanding	19,770,070	11,862,043
Convertible Preferred Stock, Liquidation Preference	$ 75,116	$ 45,070

Supplemental Financial Information - Schedule of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Disclosure of Accrued Expenses and Other Current Liabilities [Line Items]
Research and development	$ 453	$ 133
Bonuses and other employee liabilities	600
Professional fees	506	200
Other	52	90
Total accrued expenses and other current liabilities	$ 1,611	$ 423

Convertible Preferred Stock, Tranche Liability and Warrant Liability - Summary of the Tranche Liability and Warrant Liability Measured at Fair Value using Level 3 Significant Unobservable Inputs (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2021 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, December 31, 2020	$ 5,413
Change in fair value	81,157
Settlement of tranche liability due to issuance of Milestone Shares	(81,190)
Settlement of warrant liability upon exercise of warrant	(5,380)
Balance, June 30, 2021	0
Series A-1 Preferred Stock Warrant
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, December 31, 2020	380
Change in fair value	5,000
Settlement of warrant liability upon exercise of warrant	(5,380)
Balance, June 30, 2021	0
Series B Tranche Rights
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, December 31, 2020	5,033
Change in fair value	76,157
Settlement of tranche liability due to issuance of Milestone Shares	(81,190)
Balance, June 30, 2021	$ 0

Stockholders' Deficit (Tables)

6 Months Ended

Jun. 30, 2021

Stockholders' Equity Note [Abstract]

Summary of Outstanding Warrants to Purchase the Company's Common Stock

As of June 30, 2021 and December 31, 2020, the remaining outstanding warrants to purchase the Company’s common stock were comprised of the following:


	Equity Upon Exercise		Exercise Price		Expiration Dates		June 30, 3021	December 31, 2020
Warrants issued in 2014		Common Stock	$	4.47		3/21/2024 - 6/30/2025	72,178		83,726
Warrants issued in 2015		Common Stock	$	4.47		6/30/2025	109,908		209,690
Warrants issued in 2016		Common Stock	$	4.47		6/30/2025	34,396		34,396
Warrants issued in 2017		Common Stock	$	4.47		6/30/2025	31,765		57,881

Total Warrants							248,247		385,693

Basis of Presentation, Summary of Significant Accounting Policies and Recent Accounting Pronouncements (Tables)

6 Months Ended

Jun. 30, 2021

Accounting Policies [Abstract]

Summary of Fair Value Measurements, Recurring and Nonrecurring


	Fair value measurements at reporting date using						Fair Value at June 30, 2021
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value at June 30, 2021
Assets included in:
Cash and cash equivalents
Money market securities	$	36,766	$	—	$	—	$	36,766

Total fair value	$	36,766	$	—	$	—	$	36,766


	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, 2020
Assets included in:
Cash and cash equivalents
Money market securities	$	36,758	$	—	$	—	$	36,758

Total fair value	$	36,758	$	—	$	—	$	36,758

Liabilities included in:
Preferred stock tranche rights liability	$	—	$	—	$	5,033	$	5,033
Preferred stock warrant liability		—		—		380		380

Total fair value	$	—	$	—	$	5,413	$	5,413

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Convertible Preferred Stock, Tranche Liability and Warrant Liability

6 Months Ended

Jun. 30, 2021

Convertible Preferred Stock Tranche Liability and Warrant Liability [Abstract]

Convertible Preferred Stock, Tranche Liability and Warrant Liability

NOTE 4. CONVERTIBLE PREFERRED STOCK, TRANCHE LIABILITY AND WARRANT LIABILIT

Convertible Preferred Stock

On November 20, 2020, the Company entered into the Series B Agreement for a private placement of up to 19,770,070 shares of Series B convertible preferred stock, $0.0001 par value per share, at an original issuance price of $3.80 per share, subject to separate closings, including: (1) 11,862,043 shares at the Initial Closing on November 20, 2020, and (2) 7,908,027 shares at a subsequent closing that would be triggered by the achievement of a specific clinical milestone. The Series B Agreement obligated the Company to issue and sell and the Series B purchasers to purchase up to a total of 7,908,027 additional shares of Series B convertible preferred stock (the “Milestone Shares”) at the same price per share upon the achievement of a certain defined clinical milestone. The determination as to whether the milestone event has been met was subject to certification by the Board and the Requisite Investors. Each Series B convertible preferred stock investor had the right, but not the obligation, to purchase all or any portion of the Milestone Shares at any time in its sole option and in its sole and absolute discretion, whether or not the Company achieved the applicable clinical milestone. See “

Series B Convertible Preferred Stock Tranche Rights Liability

” below).

As discussed above in Note 1, on June 9, 2021, the Board and the Requisite Investors elected to waive the achievement of the milestone subject to the terms and conditions of the Series B Agreement and consummate the Milestone Closing and, on June 17, 2021, the Milestone Closing occurred, resulting in the sale of 7,908,027 shares of Series B convertible preferred stock at $3.80 per share for gross proceeds of $30.0 million.

On June 22, 2021, a warrant to purchase 447,426 shares of Series

A-1

convertible preferred stock at an exercise price of $2.794 per share was exercised (see

“Series

A-1

Convertible Preferred Stock Warrant Liability”

below).

Convertible preferred stock consisted of the following (in thousands, except share and per share data):


	June 30, 2021
	Shares Authorized		Shares Issued and Outstanding		Weighted Average Issuance Price per Share		Carrying Value		Liquidation Preference
Series A		711,203		477,297	$	2.24	$	1,067	$	1,067
Series A-1		11,898,177		7,985,305		2.27		22,963		18,097
Series B		29,457,450		19,770,070		3.80		150,474		75,116

Total		42,066,830		28,232,672			$	174,504	$	94,280

	December 31, 2020
	Shares Authorized		Shares Issued and Outstanding		Weighted Average Issuance Price per Share		Carrying Value		Liquidation Preference
Series A		711,203		477,297	$	2.24	$	1,067	$	1,067
Series A-1		11,898,177		7,537,879		2.24		16,333		16,847
Series B		29,457,450		11,862,043		3.80		39,253		45,070

Total		42,066,830		19,877,219			$	56,653	$	62,984

Dividends

The holders of Series B, Series

A-1

and Series A convertible preferred stock were entitled to receive dividends ahead of, or simultaneously with, common stockholders in an amount equal to the product of (A) the dividend payable on each share of the class or series of convertible preferred stock determined, if applicable, as if all shares of such class or series of convertible preferred stock had been converted into common stock and (B) the number of shares of common stock issuable upon conversion of a share of preferred stock. No dividends have been declared since inception.

Liquidation preference

In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company, holders of Series B convertible preferred stock were entitled to receive, prior and in preference to, holders of Series

A-1

convertible preferred stock, Series A convertible preferred stock, and holders of common stock, in the amount of the original issue price plus any declared but unpaid dividends thereon. If upon occurrence of such an event, the assets and funds to be distributed among the holders of Series B convertible preferred stock were insufficient to permit full payment to such holders, the entire assets and funds of the Company legally available for distribution would have been distributed ratably among the holders of the Series B convertible preferred stock.

In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company, holders of Series

A-1

convertible preferred stock were entitled to receive, prior and in preference to, holders of Series A convertible preferred stock and holders of common stock, in the amount of the original issue price plus any declared but unpaid dividends thereon. If upon occurrence of such an event, the assets and funds to be distributed among the holders of Series

A-1

convertible preferred stock were insufficient to permit full payment to such holders, the entire assets and funds of the Company legally available for distribution would have been distributed ratably among the holders of the Series

A-1

convertible preferred stock.

In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company, holders of Series A convertible preferred stock were entitled to receive, prior and in preference to, holders of common stock, in the amount of the original issue price plus any declared but unpaid dividends thereon. If upon occurrence of such an event, the assets and funds to be distributed among the holders of Series A convertible preferred stock were insufficient to permit full payment to such holders, the entire assets and funds of the Company legally available for distribution would have been distributed ratably among the holders of the Series A convertible preferred stock.

Conversion rights

Shares of all series of convertible preferred stock were convertible into such number of fully paid and

non-assessable

shares of common stock as determined by dividing the original issuance price for such series by the applicable conversion price for such series then in effect. The initial conversion price per share for each series of convertible preferred stock was the original issue price applicable to such series as shown in the table above, subject to adjustment in the event of certain dilutive issuances. The convertible preferred stock original issuance price and conversion price were each subject to adjustment in the event of any stock dividend, stock split, combination or other similar recapitalization with respect to the convertible preferred stock.

Each share of convertible preferred stock was convertible at any time at the option of the holder at the conversion ratio then in effect. In addition, each share of convertible preferred stock was to be automatically converted into common stock at the conversion ratio then in effect upon either (a) the closing of an underwritten public offering resulting in gross proceeds to the Company of at least $75 million and at a price per share equal to at least two times the Series B original issuance price, or $7.60 (subject to adjustment in the event of any stock dividend, stock split, combination or other similar recapitalization with respect to the Series B convertible preferred stock), or (b) the date and time, or the occurrence of an event, specified in such vote or written consent of at least 67% of the holders of the then outstanding shares of Series B convertible preferred stock

If any Series B purchaser failed to purchase its respective portion of the Milestone Shares upon occurrence of the Milestone Closing, each existing share of Series B convertible preferred stock held by such stockholder would have automatically converted into one share of common stock two days after the Milestone Closing.

On July 6, 2021, in connection with the closing of the IPO, each outstanding share of Series A, Series

A-1

and Series B convertible preferred stock converted into one share of common stock.

Voting rights

Holders of convertible preferred stock were entitled to vote as a single class together with the holders of common stock and had one vote for each share of common stock into which the convertible preferred stock was convertible.

The holders of Series B convertible preferred stock were entitled to elect two directors to the Board, and the holders of Series A and Series

A-1

convertible preferred stock, voting together as a single class, were also entitled to elect two directors to the Board. The holders of common stock, exclusively and as a separate class, are entitled to elect

two directors to the Board. The final director to the Board was designated by the holders of a majority of the shares of the preferred stock and common stock, voting together as a single class.

A majority of the outstanding shares of convertible preferred stock was necessary for approving certain matters, including the ability to either increase or decrease the authorized number of directors constituting the Board, pursuant to protective provisions in the Company’s amended and restated certificate of incorporation.

Series B Convertible Preferred Stock Tranche Rights Liability

The Company concluded that the tranche liability met the definition of a freestanding financial instrument, as it was legally detachable and separately exercisable from the initial closing of the Series B convertible preferred stock. The fair value for the tranche liability was estimated as a forward contract using a valuation model, calibrated at issuance. The valuation model at issuance estimated the implied value of the Series B stock as of the expected milestone date utilizing the probability of milestone achievement, expected timing of milestone achievement, and risk-free rate. The model was calibrated such that the value of the initial tranche and the forward contract were equal to the initial tranche proceeds at issuance. Subsequently, the fair value of the liability was discounted to the valuation date and adjusted for probability of the achievement of the milestone event. The calibrated valuation model was updated as of December 31, 2020, March 31, 2021 and in the Stay Private scenario utilized in the hybrid methodology as of June 17, 2021 (the date of the Milestone Closing). Significant estimates and assumptions impacting fair value include the discount rate, expected time to the Milestone Closing, and probability of the Milestone Closing. The discount rate was equal to the risk-free rate commensurate with the estimated timing of the Milestone Closing.

The following assumptions were used in the estimation of the fair value of the tranche liability as a forward contract as of each of the dates indicated:


	June 17, 2021	December 31, 2020
Risk-free interest rate	0.07%	0.12%
Expected time to Milestone Closing (in years)	0.8	1.3
Probability of achievement of Milestone Closing	100%	65%

For the other portion of the hybrid method used as of

June

, 2021, the fair value for the tranche liability was estimated based upon an allocation of the underlying equity value, which was determined using an IPO value as estimated through analysis of IPOs for comparable guideline companies, to arrive at a value per share in the IPO scenario. The estimated fair value of the tranche liability was $81,190,000 and $5,033,000 as of the Milestone Closing on

June 17

, 2021 and December 31, 2020, respectively. The significant increase in the

June

, 2021 valuation stems from

both

a shift in methodology from an option pricing method (“OPM”) to a Hybrid Model where the concluded value of the forward tranche is derived by the sum of the probability weighted present value of the forward tranche in the Stay Private and IPO scenarios (with the former including all other potential exit scenarios other than an imminent IPO

as well as the increase in the probability of achievement of the Milestone Closing. The resulting difference in estimated fair value

was

recognized as a change in fair value within other income in the accompanying condensed statements of operations.

The tranche liability was revalued each reporting period with the change in fair value recorded in the accompanying condensed statements of operations through the issuance of the Milestone Shares on June 17, 2021. Following the Milestone Closing, the

remaining tranche

liability was reclassified to convertible preferred stock on the condensed balance sheet.

Series

A-1

Convertible Preferred Stock Warrant Liability

On October 19, 2018, the Company issued a

10-year

warrant (the “Series

A-1

Warrant”) to purchase up to an aggregate of 447,426 shares of Series

A-1

convertible preferred stock at an exercise price of $2.794 on or before October 18, 2028.

The warrant liability met the definition of a freestanding financial instrument, as it was legally detachable and separately exercisable from the initial closing of the Series

A-1

convertible preferred stock. As such, it was revalued each reporting period with the change in fair value recorded in the accompanying condensed statements of operations until the warrant was exercised on June 22, 2021.

The fair value of the warrant liability was estimated using the OPM backsolve method as of December 31, 2020 and using a hybrid method, which included an OPM backsolve in the Stay Private scenario as of June

, 2021. The following assumptions were used in the estimation of the fair value of the warrant liability using the OPM backsolve method as of each of the dates indicated:


	June 22, 2021		December 31, 2020

Risk-free interest rate		0.25%		0.13%
Expected term (in years)		2.0		2.0
Expected volatility		90%		90%
Expected dividend yield	0%		0%

The hybrid method used to value the warrant liability at

June

, 2021 considered both the underlying equity value determined using the OPM backsolve method in a Stay Private scenario, as well as the underlying equity value that was determined using an expected IPO value as estimated through analysis of IPOs for comparable guideline companies, to arrive at a value per share in the IPO scenario. The underlying equity values from each approach were probability weighted based upon the expected likelihood of each scenario. The fair value of the warrant liability was estimated to be $12.02 and $0.85 as of June

, 2021 and December 31, 2020, respectively

The following table provides a reconciliation of the tranche liability and warrant liability measured at fair value using Level 3 significant unobservable inputs (in thousands):


	Series A-1 Preferred Stock Warrant			Series B Tranche Rights			Total
Balance, December 31, 2020	$	380		$	5,033		$	5,413
Change in fair value		5,000			76,157			81,157
Settlement of tranche liability due to issuance of Milestone Shares		—			(81,190	)		(81,190	)
Settlement of warrant liability upon exercise of warrant		(5,380	)		—			(5,380	)

Balance, June 30, 2021	$	—		$	—		$	—

Cover Page - shares	6 Months Ended
Cover Page - shares	Jun. 30, 2021	Aug. 13, 2021
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Entity Registrant Name	Acumen Pharmaceuticals, Inc.
Entity Central Index Key	0001576885
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-40551
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	No
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		40,468,087

Condensed Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
Condensed Statements of Cash Flows - USD ($) $ in Thousands	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities
Net loss	$ (88,355)	$ (4,080)
Adjustments to reconcile net loss to net cash used in operating activities:
Change in fair value of preferred stock tranche rights liability and preferred stock warrant liability	81,157
Stock-based compensation expense	253	77
Changes in operating assets and liabilities:
Grant receivable		30
Prepaid expenses and other current assets	(1,108)	406
Other assets	(13)	(270)
Accounts payable	741	380
Accrued expenses and other current liabilities	691	147
Net cash used in operating activities	(6,634)	(3,310)
Cash flows from investing activities
Purchase of fixed assets	(6)
Net cash used in investing activities	(6)
Cash flows from financing activities
Proceeds from issuance of Series B milestone shares, net of issuance costs	30,031
Payments for deferred offering costs	(220)
Net cash provided by financing activities	31,675
Net change in cash and cash equivalents	25,035	(3,310)
Cash and cash equivalents, at the beginning of the period	43,777	6,552
Cash and cash equivalents, at the end of the period	68,812	$ 3,242
Supplemental disclosure of noncash financing activities
Reclassification of preferred stock tranche rights liability upon share issuance	81,190
Reclassification Of Warrant Liability Upon Exercise Of Preferred Stock Warrant	5,380
Deferred offering costs in accounts payable	1,635
Deferred offering costs in accrued expenses and other current liabilities	497
Common Stock Warrants [Member]
Cash flows from financing activities
Proceeds from exercise of warrants	614
Series A -1 Convertible Preferred Stock Warrant Liability [Member]
Cash flows from financing activities
Proceeds from exercise of warrants	$ 1,250

Basis of Presentation, Summary of Significant Accounting Policies and Recent Accounting Pronouncements (Policies)

6 Months Ended

Jun. 30, 2021

Accounting Policies [Abstract]

Basis of Presentation

10-Q

and Article 10 of Regulation

S-X.

Emerging Growth Company

Use of Estimates

COVID-19,

Cash and Cash Equivalents

36.8

million in cash equivalents as of

both

June

30, 2021 and December 31,

2020.

Concentrations of Credit Risk

The Company has not experienced any losses on these deposits.

Fair Value of Financial Instruments

The Company’s financial assets and liabilities are accounted for in accordance with Accounting Standards Codification (“ASC”) 820,

Fair Value Measurements and Disclosure

Level 1— Observable inputs, such as quoted prices in active markets for identical assets or liabilities.

Level 3—Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions.


	Fair value measurements at reporting date using						Fair Value at June 30, 2021
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value at June 30, 2021
Assets included in:
Cash and cash equivalents
Money market securities	$	36,766	$	—	$	—	$	36,766

Total fair value	$	36,766	$	—	$	—	$	36,766


	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, 2020
Assets included in:
Cash and cash equivalents
Money market securities	$	36,758	$	—	$	—	$	36,758

Total fair value	$	36,758	$	—	$	—	$	36,758

Liabilities included in:
Preferred stock tranche rights liability	$	—	$	—	$	5,033	$	5,033
Preferred stock warrant liability		—		—		380		380

Total fair value	$	—	$	—	$	5,413	$	5,413

Refer to Note 4 for further information about the Level 3 rollforward of activity and Level 3 inputs.

Grant Receivable

June 30, 2021 and December 31, 2020.

Convertible Preferred Stock

The Company records shares of convertible preferred stock at their respective fair values on the dates of issuance, net of issuance costs. The Company has applied the guidance in ASC

480-10-S99-3A,

SEC Staff Announcement: Classification and Measurement of Redeemable Securities

and has therefore classified the Series A, Series

A-1

Preferred Stock Tranche Rights Liability

Preferred Stock Warrant Liability

The Company accounted for the warrant to purchase Series

A-1

Common Stock Warrants

Derivatives and Hedging

Grant and Other Revenue Recognition

The Company’s NIH grant is not within the scope of ASC 606,

Revenue from Contracts with Customers

(“ASC 606”)

as the grant does not meet the definition of a contract with a customer. The Company has concluded that the grant meets the definition of a contribution and is a

non-reciprocal

transaction, and management has also concluded that Subtopic

958-605,

Not-for-Profit-Entities-Revenue

Recognition

does not apply, as Acumen is a business entity and the grant is with a governmental agency.

The Company believes the recognition of revenue as costs are incurred and amounts become realizable is analogous to the concept of transfer of control of a service over time under ASC 606.

Research and Development Expense

Research and Development Expenses

Stock-based Compensation

The Company expenses stock-based compensation to employees,

non-employees

non-employee’s

roles within the Company. Forfeitures are recorded as they occur. See also Note 6 below.

Income Taxes

Income taxes are recorded in accordance with ASC 740,

Income Taxes

Net Loss Per Share of Common Stock

Basic net loss per share of common stock is calculated using the

two-class

if-converted

method). See Note 8 below.

Segment Information

Recently Issued Accounting Pronouncements

In February 2016, the FASB issued ASU

No. 2016-02,

Leases (Topic 842)

In December 2019, the FASB issued ASU

No. 2019-12,

Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes

(“ASU

2019-12”),

which is intended to simplify various aspects related to accounting for income taxes. ASU

2019-12

Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2021

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

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 six months ended June 30, 2021 with the following weighted average assumptions:


Risk-free interest rate		0.4% - 0.5%
Expected term in years		5.3 - 6.3
Expected volatility		90%
Expected dividend yield		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 December 31, 2020		1,001,517	$	1.13
Options granted		2,663,084		2.21

Outstanding at June 30, 2021		3,664,601	$	1.92		8.9	$	51,625

Vested and exercisable at June 30, 2021		872,961	$	1.19		7.3	$	12,941

As of June 30, 2021, total unrecognized compensation costs related to unvested stock option awards granted was approximately

3.4

million, which the Company expects to recognize over a weighted-average period of approximately

3.3

years

Summary of Stock-Based Compensation Expense Related to Stock Options

The Company recorded stock-based compensation expense related to stock options in the following expense categories of its condensed statements of operations for the periods shown:


	Three Months Ended June 30,				Six Months Ended June 30,
	2021		2020		2021		2020
General and administrative	$	79	$	26	$	159	$	52
Research and development		47		13		94		26

Total stock-based compensation	$	127	$	38	$	253	$	77

Summary of Assumptions Used for Valuation of Fair Value of Stock

As of December 31, 2020, the Company derived the fair value of its common stock with the assistance of an independent third-party valuation firm utilizing the following assumptions:


Risk-free interest rate			0.13%
Expected time to liquidity event in years			2.0
Expected volatility			90%
Expected dividend yield			0%

Subsequent Events	6 Months Ended
Subsequent Events	Jun. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	NOTE 9. SUBSEQUENT EVENTS The Company has completed an evaluation of all subsequent events through August 16, 2021 to ensure that these financial statements include appropriate disclosure of events both recognized in the financial statements and events which occurred but were not recognized in the financial statements. Except as described below, the Company has concluded that no subsequent event has occurred that requires disclosure. Initial Public Offering On July 6, 2021, the Company issued 9,999,999 shares of common stock in an IPO, and on July 8, 2021, the Company issued an additional 1,499,999 shares of common stock that were purchased by the underwriters pursuant to the underwriters’ option to purchase additional shares at the public offering price less underwriting discounts and commissions. The price to the public for each share was $16.00. The aggregate net proceeds from the Company’s IPO, after underwriting discounts and commissions and other offering expenses of $15.4 million, were $168.6 million . On July 6, 2021, in connection with the closing of the IPO, 477,297 shares of Series A, 7,985,305 shares of Series A-1, and 19,770,070 shares of Series B convertible preferred stock, respectively, automatically converted into an equal number of shares of common stock and warrants to purchase shares of common stock were automatically net exercised for the purchase of an aggregate of 178,847 shares of common stock. As a result of the IPO, the underwriters’ exercise of their option, the conversions of the Series A, A-1 and B convertible preferred stock , and the exercise of the warrants , the Company’s total number of outstanding shares increased by 39,911,517 immediately following the closing of the IPO. Authorized Shares Effective upon the closing of the IPO on July 6, 2021, the Company amended its certificate of incorporation such that the total number of shares of all classes of capital stock authorized to be issued was increased to 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 with a par value of $0.0001. Each share of common stock is entitled to one voting right. 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 July 6, 2021. Initially, 3,550,000 new shares, plus any shares that were still available for future grants under the 2013 Plan, as well as any shares that are returned due to expiration or other termination, forfeiture, withholding or reacquisition, may be issued under the 2021 Plan. Employee Stock Purchase Plan The 2021 Employee Stock Purchase Plan (the “ESPP”), which permits employees to purchase shares of the Company’s common stock, became effective on July 6, 2021. A total of 375,000 shares of our common stock will initially be reserved for issuance under the ESPP.

Stock-Based Compensation - Summary of Stock-Based Compensation Expense Related to Stock Options (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 127	$ 38	$ 253	$ 77
General and Administrative Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	79	26	159	52
Research and Development Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 47	$ 13	$ 94	$ 26

Stock-Based Compensation - Summary of Assumptions Used for Valuation of Fair Value of Stock (Detail) - 2013 Amended And Restated Stock Performance Plan [Member]	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Valuation Technique, Option Pricing Model [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Risk-free interest rate, minimum	0.40%
Risk-free interest rate, maximum	0.50%
Expected volatility	90.00%
Expected dividend yield	0.00%
Third Party Valuation [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Risk-free interest rate		0.13%
Expected time to liquidity event in years		2 years
Expected volatility		90.00%
Expected dividend yield		0.00%
Minimum [Member] \| Valuation Technique, Option Pricing Model [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Expected term in years	5 years 3 months 18 days
Maximum [Member] \| Valuation Technique, Option Pricing Model [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Expected term in years	6 years 3 months 18 days

Convertible Preferred Stock, Tranche Liability and Warrant Liability - Additional Information (Detail)		6 Months Ended
	Jun. 17, 2021 USD ($) $ / shares shares	Jun. 30, 2021 USD ($) $ / shares shares	Jun. 22, 2021 $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Nov. 20, 2020 $ / shares shares	Oct. 19, 2018 $ / shares shares
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Shares Issued		28,232,672		19,877,219
Proceeds from convertible preferred stock \| $		$ 30,031,000
Series A -1 Convertible Preferred Stock Warrant Liability [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Class of warrants or rights number of shares covered by warrants or rights						447,426
Class of warrants or rights term						10 years
Class of warrants or right exercise price per share \| $ / shares						$ 2.794
Class of warrants or rights expiry date						Oct. 18, 2028
Fair value of warrant liability per share \| $ / shares			$ 12.02	$ 0.85
Underlying Equity Value [Member] \| Series B Convertible Preferred Stock Tranche Rights Liability [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Financial liabilities at fair value \| $	$ 81,190,000			$ 5,033,000
Series A-1 Redeemable Convertible Preferred Stock [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Shares Issued		7,985,305		7,537,879
Class of warrants or rights number of shares covered by warrants or rights			447,426
Class of warrants or right exercise price per share \| $ / shares			$ 2.794
Prospective Conversion of Temporary Equity into Permanent Equity [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Number of times the redeemable convertible preferred stock equal to the share issue price		2
Sale of stock issue price per share \| $ / shares		$ 7.60
Percentage of votes in terms of shareholding needed for conversion into permanent equity		67.00%
Prospective Conversion of Temporary Equity into Permanent Equity [Member] \| Minimum [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Proceeds from initial public offer \| $		$ 75,000,000
Private Placement [Member] \| Series B Redeemable Convertible Preferred Stock [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Shares Issued					19,770,070
Temporary equity par or stated value per share \| $ / shares					$ 0.0001
Temporary equity issue price per share \| $ / shares					$ 3.80
Private Placement [Member] \| Series B Redeemable Convertible Preferred Stock [Member] \| Closing of Milestone [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Temporary equity issue price per share \| $ / shares	$ 3.80
Temporary equity shares issued during the period shares	7,908,027
Proceeds from convertible preferred stock \| $	$ 30,000,000
Private Placement [Member] \| Series B Redeemable Convertible Preferred Stock [Member] \| Initial Closing [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Shares Issued					11,862,043
Private Placement [Member] \| Series B Redeemable Convertible Preferred Stock [Member] \| Achievement of Milestone [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Temporary equity milestone shares					7,908,027

Convertible Preferred Stock, Tranche Liability and Warrant Liability - Summary of Assumptions Used in Estimating the Fair Value of Preferred Stock Tranche Liability (Detail)		12 Months Ended
	Jun. 17, 2021	Dec. 31, 2020
Convertible Preferred Stock Tranche Liability and Warrant Liability [Abstract]
Risk-free interest rate	0.07%	0.12%
Expected time to Milestone Closing (in years)	9 months 18 days	1 year 3 months 18 days
Probability of achievement of Milestone Closing	100.00%	65.00%

Basis of Presentation, Summary of Significant Accounting Policies and Recent Accounting Pronouncements - Summary of Fair Value Measurements, Recurring and Nonrecurring (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Assets included in:
Fair value	$ 36,766	$ 36,758
Liabilities included in:
Fair value		5,413
Preferred stock tranche rights liability [Member]
Liabilities included in:
Fair value		5,033
Preferred stock warrant liability [Member]
Liabilities included in:
Fair value		380
Cash and Cash Equivalents [Member] \| Money Market Funds [Member]
Assets included in:
Fair value	36,766	36,758
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets included in:
Fair value	36,766	36,758
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| Cash and Cash Equivalents [Member] \| Money Market Funds [Member]
Assets included in:
Fair value	$ 36,766	36,758
Significant Unobservable Inputs (Level 3) [Member]
Liabilities included in:
Fair value		5,413
Significant Unobservable Inputs (Level 3) [Member] \| Preferred stock tranche rights liability [Member]
Liabilities included in:
Fair value		5,033
Significant Unobservable Inputs (Level 3) [Member] \| Preferred stock warrant liability [Member]
Liabilities included in:
Fair value		$ 380

Basis of Presentation, Summary of Significant Accounting Policies and Recent Accounting Pronouncements - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Accounting Policies [Abstract]
Cash equivalents	$ 36,800,000		$ 36,800,000
Uncertain tax positions	0		$ 0
Uncertain tax positions, interest or penalties recorded	$ 0	$ 0

Supplemental Financial Information

6 Months Ended

Jun. 30, 2021

Supplemental Financial Information [Abstract]

Supplemental Financial Information

NOTE 3. SUPPLEMENTAL FINANCIAL INFORMATION

Prepaid expenses and other current assets consisted of the following (in thousands):


	June 30, 2021		December 31, 2020
Research and development service agreements	$	1,491	$	432
Prepaid raw materials		65		91
Other		95		20

Total prepaid expenses and other current assets	$	1,651	$	543

Accrued expenses and other current liabilities consisted of the following (in thousands):


	June 30, 2021		December 31, 2020
Research and development	$	453	$	133
Bonuses and other employee liabilities		600		—
Professional fees		506		200
Other		52		90

Total accrued expenses and other current liabilitie s	$	1,611	$	423

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation by share based payment arrangement vesting period	3 months
2013 Amended And Restated Stock Performance Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation by share based payment arrangement number of shares authorized	4,179,202
Common stock shares reserved for future issuance	483,681
Share price	$ 16.00		$ 0.83
Share based compensation by share based payment arrangement weighted average grant date fair value of options granted	$ 1.34
Share based compensation by share based payment arrangement non vested options granted during the period	2,663,084	0
Share based compensation by share based payment arrangement unrecognized compensation costs non vested options	$ 3.4
Share based compensation by share based payment arrangement unrecognized compensation costs weighted aveage period of recognition	3 years 3 months 18 days
2013 Amended And Restated Stock Performance Plan [Member] \| Stock Options Granted After December 31, 2017 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation by share based payment arrangement contractual term	10 years
2013 Amended And Restated Stock Performance Plan [Member] \| Stock Options Granted After December 31, 2017 [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation by share based payment arrangement vesting period	24 months
2013 Amended And Restated Stock Performance Plan [Member] \| Stock Options Granted After December 31, 2017 [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation by share based payment arrangement vesting period	36 months
2013 Amended And Restated Stock Performance Plan [Member] \| Stock Options Granted Before December 31, 2017 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation by share based payment arrangement contractual term	10 years
2013 Amended And Restated Stock Performance Plan [Member] \| Stock Options Granted Before December 31, 2017 [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation by share based payment arrangement vesting period	24 months

Convertible Preferred Stock, Tranche Liability and Warrant Liability - Summary of Convertible preferred stock (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Temporary Equity [Line Items]
Shares Authorized	42,066,830	42,066,830
Shares Issued	28,232,672	19,877,219
Shares Outstanding	28,232,672	19,877,219
Carrying Value	$ 174,504	$ 56,653
Liquidation Preference	$ 94,280	$ 62,984
Series A
Temporary Equity [Line Items]
Shares Authorized	711,203	711,203
Shares Issued	477,297	477,297
Shares Outstanding	477,297	477,297
Weighted Average Issuance Price per Share	$ 2.24	$ 2.24
Carrying Value	$ 1,067	$ 1,067
Liquidation Preference	$ 1,067	$ 1,067
Series A-1
Temporary Equity [Line Items]
Shares Authorized	11,898,177	11,898,177
Shares Issued	7,985,305	7,537,879
Shares Outstanding	7,985,305	7,537,879
Weighted Average Issuance Price per Share	$ 2.27	$ 2.24
Carrying Value	$ 22,963	$ 16,333
Liquidation Preference	$ 18,097	$ 16,847
Series B
Temporary Equity [Line Items]
Shares Authorized	29,457,450	29,457,450
Shares Issued	19,770,070	11,862,043
Shares Outstanding	19,770,070	11,862,043
Weighted Average Issuance Price per Share	$ 3.80	$ 3.80
Carrying Value	$ 150,474	$ 39,253
Liquidation Preference	$ 75,116	$ 45,070

Description of Organization and Business Operations	6 Months Ended
Description of Organization and Business Operations	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Organization and Business Operations	NOTE 1. DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS Acumen Pharmaceuticals, Inc. (“Acumen” or the “Company”) was incorporated in 1996 in the state of Delaware. Acumen discovers and develops targeted therapies for the treatment of Alzheimer’s disease. Acumen’s lead drug candidate, ACU193, is a humanized monoclonal antibody which selectively targets amyloid-beta oligomers (“AßOs”). Acumen and Merck & Co. discovered and developed ACU193 through an eight-year research collaboration. Acumen currently holds exclusive rights to the program. The Company submitted an Investigation Drug Application (“IND”) for ACU193 to the Food and Drug Administration (“FDA”) in the fourth quarter of 2020. We initiated a Phase 1 clinical trial of ACU193 in patients with early Alzheimer’s disease in April 2021. The Company is subject to the uncertainty of whether the Company’s intellectual property will develop into successful commercial products . November 2020 Reverse Stock Split On November 20, 2020, the Company effected a 1-for-30 reverse stock split of its authorized, issued and outstanding shares of common stock and convertible preferred stock. Accordingly, all share and per share amounts for the periods presented in the accompanying financial statements and these notes have been adjusted retroactively, where applicable, to reflect this reverse stock split. On November 20, 2020, the Company also increased the number of shares of preferred stock and common stock authorized for issuance (see Note 5). June 2021 Reverse Stock Split The Company’s Board of Directors (“Board”) approved a reverse split of shares of the Company’s common stock and convertible preferred stock on a 1-for-1.49 basis (the “June 2021 Reverse Stock Split”), which was effected on June 23, 2021. The par value and the number of authorized shares of the convertible preferred stock and common stock were not adjusted in connection with the June 2021 Reverse Stock Split. All references to common stock, convertible preferred stock, warrants to purchase common stock, warrants to purchase convertible preferred stock, options to purchase common stock, share data, per share data and related information contained in the financial statements have been retrospectively adjusted to reflect the effect of the June 2021 Reverse Stock Split for all periods presented. No fractional shares of the Company’s common stock were issued in connection with the June 2021 Reverse Stock Split. Any fractional share resulting from the June 2021 Reverse Stock Split was rounded down to the nearest whole share, and any stockholder entitled to a fractional share as a result of the June 2021 Reverse Stock Split will receive a cash payment in lieu of receiving fractional shares. Initial Public Offering On July 6, 2021, the Company issued 9,999,999 shares of common stock in an initial public offering (“IPO”), and on July 8, 2021, the Company issued an additional 1,499,999 shares of common stock that were purchased by the underwriters pursuant to the underwriters’ option to purchase additional shares at the public offering price less underwriting discounts and commissions. The price to the public for each share was $16.00. The aggregate net proceeds from the Company’s IPO, after underwriting discounts and commissions and other offering expenses of $15.4 million, were $168.6 million. On July 6, 2021, in connection with the closing of the IPO, 477,297 shares of Series A, 7,985,305 shares of Series A-1, and 19,770,070 shares of Series B convertible preferred stock, respectively, automatically converted into an equal number of shares of common stock and warrants to purchase shares of common stock were automatically net exercised for the purchase of an aggregate of 178,847 shares of common stock. As a result of the IPO, the underwriters’ exercise of their option, the conversions of the Series A, A-1 and B convertible preferred stock, and the exercise of the warrants, the Company’s total number of outstanding shares increased by 39,911,517 immediately following the closing of the IPO. See Note 9 for further information regarding subsequent events. 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 June 30, 2021 and December 31, 2020, the Company had an accumulated deficit of $115.3 million and $27.0 million, respectively, and working capital of $66.1 million and $38.1 million, respectively. The Company has historically relied on raising capital from venture capital firms and private investors and funding from a government grant to finance its operations. On June 9, 2021, the Board and the holders of more than 67% of the then outstanding shares of Series B convertible preferred stock held by the Series B purchasers (the “Requisite Investors”) elected to waive the achievement of the milestone subject to the terms and conditions of the Series B Preferred Stock Purchase Agreement (the “Series B Agreement”) and consummate the subsequent closing (the “Milestone Closing”) (see Note 4). On June 17, 2021, the Milestone Closing for the Series B convertible preferred stock occurred, resulting in the sale of 7,908,027 shares of Series B convertible preferred stock at $3.80 per share for gross proceeds of $30.0 million. As a result of the Milestone Closing and the closing of the Company’s IPO on July 6, 2021, management believes that its existing financial resources are sufficient to continue operating activities at least through 2024. 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 may 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 impact of the coronavirus (“COVID-19”) outbreak on the Company’s results of operations, financial position and cash flows will depend on future developments, including the duration and spread of the outbreak and related advisories and restrictions. These developments and the impact of COVID-19 on the financial markets and the overall economy are highly uncertain and cannot be predicted. If the financial markets and/or the overall economy are impacted for an extended period, the Company’s results of operations, financial position and cash flows may be materially adversely affected.

Commitments and Contingencies

6 Months Ended

Jun. 30, 2021

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

NOTE 7. 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.

Leases

The Company has been subleasing space in Indiana since March 1, 2020 under a lease that expired on December 31, 2020. The Company executed a new sublease for this space that was effective February 1, 2021. The term of the sublease is for 31 months, expiring on August 30, 2023. The Company will pay monthly rent of $12,719 and is also allowing others to sublease a portion of the space from the Company for less than a

one-year

period. As of June 30, 2021, the remaining aggregate minimum rent obligation over the remaining term was approximately $331,000.

At June 30, 2021, future minimum lease payments under lease agreements (including short-term leases) associated with our operations were as follows (in thousands):


Year ended December 31, 2021 (remaining 6 months)	$	77
Year ended December 31, 2022		153
Year ended December 31, 2023		102

Total	$	332

Supplemental Financial Information (Tables)

6 Months Ended

Jun. 30, 2021

Supplemental Financial Information [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following (in thousands):


	June 30, 2021		December 31, 2020
Research and development service agreements	$	1,491	$	432
Prepaid raw materials		65		91
Other		95		20

Total prepaid expenses and other current assets	$	1,651	$	543

Schedule of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):


	June 30, 2021		December 31, 2020
Research and development	$	453	$	133
Bonuses and other employee liabilities		600		—
Professional fees		506		200
Other		52		90

Total accrued expenses and other current liabilitie s	$	1,611	$	423

Stockholders' Deficit - Summary of Outstanding Warrants to Purchase the Company's Common Stock (Detail) - Common Stock Warrants [Member] - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Class of Warrant or Right [Line Items]
Total Warrants	248,247	385,693
Warrants issued in 2014 [Member]
Class of Warrant or Right [Line Items]
Exercise Price	$ 4.47
Total Warrants	72,178	83,726
Warrants issued in 2015 [Member]
Class of Warrant or Right [Line Items]
Exercise Price	$ 4.47
Expiration Dates	Jun. 30, 2025
Total Warrants	109,908	209,690
Warrants issued in 2016 [Member]
Class of Warrant or Right [Line Items]
Exercise Price	$ 4.47
Expiration Dates	Jun. 30, 2025
Total Warrants	34,396	34,396
Warrants issued in 2017 [Member]
Class of Warrant or Right [Line Items]
Exercise Price	$ 4.47
Expiration Dates	Jun. 30, 2025
Total Warrants	31,765	57,881
Minimum [Member] \| Warrants issued in 2014 [Member]
Class of Warrant or Right [Line Items]
Expiration Dates	Mar. 21, 2024
Maximum [Member] \| Warrants issued in 2014 [Member]
Class of Warrant or Right [Line Items]
Expiration Dates	Jun. 30, 2025

Description of Organization and Business Operations - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands					6 Months Ended
	Jul. 06, 2021	Jun. 23, 2021	Jun. 17, 2021	Nov. 20, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 09, 2021	Dec. 31, 2020
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Stockholders' equity, reverse stock split		1-for-1.49		1-for-30
Conversion of stock, shares converted					32,145,520	9,853,193
Accumulated deficit					$ (115,320)			$ (26,965)
Working capital					$ 66,100			$ 38,100
Total number of outstanding shares increased	39,911,517
Series B Convertible Preferred Stock [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sale of stock, number of shares issued in transaction			7,908,027
Sale of stock, price per share			$ 3.80
Percentage of stockholders elected to waive achievement of milestone							67.00%
Sale of stock, consideration received on transaction			$ 30,000
Subsequent Event [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total number of outstanding shares increased	39,911,517
Subsequent Event [Member] \| Common Stock Warrants [Member] \| Common Stock [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of securities called by warrants or rights	178,847
Subsequent Event [Member] \| Series A Convertible Preferred Stock [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Conversion of stock, shares converted	477,297
Subsequent Event [Member] \| Series A-1 Convertible Preferred Stock [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Conversion of stock, shares converted	7,985,305
Subsequent Event [Member] \| Series B Convertible Preferred Stock [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Conversion of stock, shares converted	19,770,070
Subsequent Event [Member] \| IPO [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sale of stock, number of shares issued in transaction	9,999,999
Underwriting shares	1,499,999
Sale of stock, price per share	$ 16.00
Sale of stock, consideration received on transaction	$ 168,600
underwriting discounts and commissions and other offering expenses	$ 15,400

Convertible Preferred Stock, Tranche Liability and Warrant Liability - Summary of Fair Value of the Warrant Liability (Detail) - Series A -1 Convertible Preferred Stock Warrant Liability [Member]	Jun. 22, 2021 yr	Dec. 31, 2020 yr
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.0025	0.0013
Expected term (in years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	2.0	2.0
Expected volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.90	0.90
Expected dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0	0

Supplemental Financial Information - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Disclosure Of Prepaid Expenses And Other Current Assets [Line Items]
Research and development service agreements	$ 1,491	$ 432
Prepaid raw materials	65	91
Other	95	20
Total prepaid expenses and other current assets	$ 1,651	$ 543

Convertible Preferred Stock, Tranche Liability and Warrant Liability (Tables)

6 Months Ended

Jun. 30, 2021

Convertible Preferred Stock Tranche Liability and Warrant Liability [Abstract]

Summary of Convertible preferred stock

Convertible preferred stock consisted of the following (in thousands, except share and per share data):


	June 30, 2021
	Shares Authorized		Shares Issued and Outstanding		Weighted Average Issuance Price per Share		Carrying Value		Liquidation Preference
Series A		711,203		477,297	$	2.24	$	1,067	$	1,067
Series A-1		11,898,177		7,985,305		2.27		22,963		18,097
Series B		29,457,450		19,770,070		3.80		150,474		75,116

Total		42,066,830		28,232,672			$	174,504	$	94,280

	December 31, 2020
	Shares Authorized		Shares Issued and Outstanding		Weighted Average Issuance Price per Share		Carrying Value		Liquidation Preference
Series A		711,203		477,297	$	2.24	$	1,067	$	1,067
Series A-1		11,898,177		7,537,879		2.24		16,333		16,847
Series B		29,457,450		11,862,043		3.80		39,253		45,070

Total		42,066,830		19,877,219			$	56,653	$	62,984

Summary of Assumptions Used in Estimating the Fair Value of Preferred Stock Tranche Liability

The following assumptions were used in the estimation of the fair value of the tranche liability as a forward contract as of each of the dates indicated:


	June 17, 2021	December 31, 2020
Risk-free interest rate	0.07%	0.12%
Expected time to Milestone Closing (in years)	0.8	1.3
Probability of achievement of Milestone Closing	100%	65%

Summary of Fair Value of the Warrant Liability

The following assumptions were used in the estimation of the fair value of the warrant liability using the OPM backsolve method as of each of the dates indicated:


	June 22, 2021		December 31, 2020

Risk-free interest rate		0.25%		0.13%
Expected term (in years)		2.0		2.0
Expected volatility		90%		90%
Expected dividend yield	0%		0%

Summary of the Tranche Liability and Warrant Liability Measured at Fair Value using Level 3 Significant Unobservable Inputs

The following table provides a reconciliation of the tranche liability and warrant liability measured at fair value using Level 3 significant unobservable inputs (in thousands):


	Series A-1 Preferred Stock Warrant			Series B Tranche Rights			Total
Balance, December 31, 2020	$	380		$	5,033		$	5,413
Change in fair value		5,000			76,157			81,157
Settlement of tranche liability due to issuance of Milestone Shares		—			(81,190	)		(81,190	)
Settlement of warrant liability upon exercise of warrant		(5,380	)		—			(5,380	)

Balance, June 30, 2021	$	—		$	—		$	—

Condensed Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Condensed Statements of Operations - USD ($) $ in Thousands	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Grant and other revenue		$ 151		$ 377
Operating expenses
Research and development	$ 2,254	1,927	$ 4,832	3,977
General and administrative	1,187	259	2,402	481
Total operating expenses	3,441	2,186	7,234	4,458
Loss from operations	(3,441)	(2,035)	(7,234)	(4,081)
Other income (expense)
Interest income	4		8	1
Change in fair value of preferred stock tranche rights liability and preferred stock warrant liability	(57,940)		(81,157)
Other income	19		28
Total other income (expense)	(57,917)		(81,121)	1
Net loss attributable to common stockholders	$ (61,358)	$ (2,035)	$ (88,355)	$ (4,080)
Net loss per common share, basic and diluted	$ (141.93)	$ (4.86)	$ (207.52)	$ (9.73)
Weighted-average shares outstanding, basic and diluted	432,325	419,124	425,761	419,124

Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions			6 Months Ended
	Jul. 06, 2021	Jun. 17, 2021	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Subsequent Event [Line Items]
Conversion of stock, shares converted			32,145,520	9,853,193
Common stock shares authorized			50,500,000		50,500,000
Common stock par or stated value per share			$ 0.0001		$ 0.0001
Common stock shares voting rights			one
Total number of outstanding shares increased	39,911,517
Series B Convertible Preferred Stock [Member]
Subsequent Event [Line Items]
Sale of stock, Number of shares issued in transaction		7,908,027
Sale of stock, price per share		$ 3.80
Sale of stock, consideration received on transaction		$ 30.0
Subsequent Event [Member]
Subsequent Event [Line Items]
Preferred stock, shares authorized	10,000,000
Preferred stock, par or stated value per share	$ 0.0001
Total shares authorized	310,000,000
Common stock par or stated value per share	$ 0.0001
Common stock shares voting rights	one
Total number of outstanding shares increased	39,911,517
Subsequent Event [Member] \| Common Stock [Member]
Subsequent Event [Line Items]
Common stock shares authorized	300,000,000
Subsequent Event [Member] \| Common Stock Warrants [Member] \| Common Stock [Member]
Subsequent Event [Line Items]
Number of securities called by warrants or rights	178,847
Subsequent Event [Member] \| Series A Convertible Preferred Stock [Member]
Subsequent Event [Line Items]
Conversion of stock, shares converted	477,297
Subsequent Event [Member] \| Series A-1 Convertible Preferred Stock [Member]
Subsequent Event [Line Items]
Conversion of stock, shares converted	7,985,305
Subsequent Event [Member] \| Series B Convertible Preferred Stock [Member]
Subsequent Event [Line Items]
Conversion of stock, shares converted	19,770,070
Subsequent Event [Member] \| IPO [Member]
Subsequent Event [Line Items]
Sale of stock, Number of shares issued in transaction	9,999,999
Underwriting shares	1,499,999
Sale of stock, price per share	$ 16.00
underwriting discounts and commissions and other offering expenses	$ 15.4
Sale of stock, consideration received on transaction	$ 168.6
Subsequent Event [Member] \| Employee Stock [Member]
Subsequent Event [Line Items]
Common stock, capital shares reserved for future issuance	375,000
Subsequent Event [Member] \| 2021 Equity Incentive Plan [Member]
Subsequent Event [Line Items]
Shares available for future grant	3,550,000

Commitments and Contingencies - Additional Information (Detail) - New Operating Sublease [Member]	5 Months Ended
	Jun. 30, 2021 USD ($)
Other Commitments [Line Items]
Operating sublease monthly rent minimum	$ 12,719
Operating sublease minimum rent obligation over the remaining term	$ 331,000
Term of operating sublease	31 months

Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 68,812	$ 43,777
Grant receivable	109	109
Prepaid expenses and other current assets	1,651	543
Total current assets	70,572	44,429
Property and equipment, net	6
Deferred offering costs	2,352
Other assets	13	0
Total assets	72,943	44,429
Current liabilities
Accounts payable	2,907	531
Accrued expenses and other current liabilities	1,611	423
Preferred stock tranche rights liability		5,033
Preferred stock warrant liability		380
Total liabilities	4,518	6,367
Convertible Preferred Stock, Issued	174,504	56,653
Stockholders' deficit
Additional paid-in capital	9,241	8,374
Accumulated deficit	(115,320)	(26,965)
Total stockholders' deficit	(106,079)	(18,591)
Total liabilities, convertible preferred stock and stockholders' deficit	72,943	44,429
Series A Convertible Preferred Stock [Member]
Current liabilities
Convertible Preferred Stock, Issued	1,067	1,067
Stockholders' deficit
Total stockholders' deficit	1,067	1,067
Series A-1 Convertible Preferred Stock [Member]
Current liabilities
Convertible Preferred Stock, Issued	22,963	16,333
Stockholders' deficit
Total stockholders' deficit	22,963	16,333
Series B Convertible Preferred Stock [Member]
Current liabilities
Convertible Preferred Stock, Issued	150,474	39,253
Stockholders' deficit
Total stockholders' deficit	$ 150,474	$ 39,253

Stock-Based Compensation - Summary of Stock Option Activity (Detail) - Two Thousand And Thirteen Amended And Restated Stock Performance Plan [Member] - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Stock Options	1,001,517
Options granted, Stock Options	2,663,084	0
Ending balance, Stock Options	3,664,601
Vested and exercisable, Stock Options	872,961
Beginning balance, Weighted Average Exercise Price	$ 1.13
Options granted, Weighted Average Exercise Price	2.21
Ending balance, Weighted Average Exercise Price	1.92
Vested and exercisable, Weighted Average Exercise Price	$ 1.19
Weighted Average Remaining Contractual Life (in years)	8 years 10 months 24 days
Vested and exercisable, Weighted Average Remaining Contractual Life (in years)	7 years 3 months 18 days
Ending balance, Aggregate Intrinsic Value	$ 51,625
Vested and exercisable, Aggregate Intrinsic Value	$ 12,941

Condensed Statement of Changes in Convertible Preferred Stock and Stockholders' Deficit - USD ($) $ in Thousands	Total	Series A Convertible Preferred Stock [Member]	Series A-1 Convertible Preferred Stock [Member]	Series B Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]
Opening balance at Dec. 31, 2019	$ (11,420)	$ 1,067	$ 16,333			$ 8,220	$ (19,640)
Opening balance (Shares) at Dec. 31, 2019		477,297	7,537,879		419,124
Share-based compensation	77					77
Net loss	(4,080)						(4,080)
Closing balance at Jun. 30, 2020	(15,423)	$ 1,067	$ 16,333			8,297	(23,720)
Closing balance (Shares) at Jun. 30, 2020		477,297	7,537,879		419,124
Opening balance at Mar. 31, 2020	(13,426)	$ 1,067	$ 16,333			8,259	(21,685)
Opening balance (Shares) at Mar. 31, 2020		477,297	7,537,879		419,124
Share-based compensation	38					38
Net loss	(2,035)						(2,035)
Closing balance at Jun. 30, 2020	(15,423)	$ 1,067	$ 16,333			8,297	(23,720)
Closing balance (Shares) at Jun. 30, 2020		477,297	7,537,879		419,124
Opening balance at Dec. 31, 2020	(18,591)	$ 1,067	$ 16,333	$ 39,253		8,374	(26,965)
Opening balance (Shares) at Dec. 31, 2020		477,297	7,537,879	11,862,043	419,124
Share-based compensation	253			$ 0		253
Issuance of milestone shares for cash, net of issuance costs				$ 30,031
Issuance of milestone shares for cash, net of issuance costs (Shares)				7,908,027
Exercise of preferred stock warrant			$ 1,250
Exercise of preferred stock warrant (shares)			447,426
Reclassification of preferred stock tranche rights liability upon issuance of milestone shares				$ 81,190
Reclassification of warrant liability upon exercise of preferred stock warrant	5,380		$ 5,380
Exercise of common stock warrants	614					614
Exercise of common stock warrants (Shares)					137,446
Net loss	(88,355)						(88,355)
Closing balance at Jun. 30, 2021	(106,079)	$ 1,067	$ 22,963	$ 150,474	$ 0	9,241	(115,320)
Closing balance (Shares) at Jun. 30, 2021		477,297	7,985,305	19,770,070	556,570
Opening balance at Mar. 31, 2021	(45,462)	$ 1,067	$ 16,333	$ 39,253	$ 0	8,500	(53,962)
Opening balance (Shares) at Mar. 31, 2021		477,297	7,537,879	11,862,043	419,124
Share-based compensation	127					127
Issuance of milestone shares for cash, net of issuance costs				$ 30,031
Issuance of milestone shares for cash, net of issuance costs (Shares)				7,908,027
Exercise of preferred stock warrant			$ 1,250
Exercise of preferred stock warrant (shares)			447,426
Reclassification of preferred stock tranche rights liability upon issuance of milestone shares				$ 81,190
Reclassification of warrant liability upon exercise of preferred stock warrant			$ 5,380
Exercise of common stock warrants	614					614
Exercise of common stock warrants (Shares)					137,446
Net loss	(61,358)						(61,358)
Closing balance at Jun. 30, 2021	$ (106,079)	$ 1,067	$ 22,963	$ 150,474	$ 0	$ 9,241	$ (115,320)
Closing balance (Shares) at Jun. 30, 2021		477,297	7,985,305	19,770,070	556,570

Net Loss Per Share

6 Months Ended

Jun. 30, 2021

Earnings Per Share [Abstract]

Net Loss Per Share

NOTE 8. NET LOSS PER SHARE

The Company computes loss per common share using the

two-class

method required for participating securities. Basic and diluted loss per share was the same for each period presented as the inclusion of all potential common stock outstanding would have been anti-dilutive.

The table below provides potentially dilutive securities not included in the calculation of the diluted net loss per common share because to do so would be anti-dilutive:


	Six Months Ended June 30,
	2021		2020
Shares issuable upon conversion of Series A Preferred Stock		477,297		477,297
Shares issuable upon conversion of Series A-1 Preferred Stock		7,985,305		7,537,879
Shares issuable upon conversion of Series B Preferred Stock		19,770,070		—
Shares issuable upon exercise of stock options		3,664,601		1,004,898
Shares issuable upon exercise of common stock warrants		248,247		385,693
Shares issuable upon exercise of preferred stock warrant		—		447,426

Total		32,145,520		9,853,193

Commitments and Contingencies - Summary of Future Minimum Lease Payments (Detail) - New Operating Sublease [Member] $ in Thousands	Jun. 30, 2021 USD ($)
Other Commitments [Line Items]
Year ended December 31, 2021 (remaining 6 months)	$ 77
Year ended December 31, 2022	153
Year ended December 31, 2023	102
Total	$ 332

Stockholders' Deficit - Additional Information (Detail)	6 Months Ended
Stockholders' Deficit - Additional Information (Detail)	Jun. 30, 2021 Directors $ / shares shares	Jun. 22, 2021 $ / shares	Dec. 31, 2020 $ / shares shares
Class of Stock [Line Items]
Common stock shares authorized	50,500,000		50,500,000
Temporary equity shares authorized	42,066,830		42,066,830
Common stock par or stated value per share \| $ / shares	$ 0.0001		$ 0.0001
Common stock shares voting rights	one
Number of directors entitled to be elected by the holders of common stock \| Directors	2
Warrant Exercise [Member]
Class of Stock [Line Items]
Stock issued during the period shares warrant exercise	137,446
Class of warrants or right exercise price per share \| $ / shares	$ 4.47
Series A Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Temporary equity shares authorized			711,203
Series A-1 Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Temporary equity shares authorized	11,898,177		11,898,177
Class of warrants or right exercise price per share \| $ / shares		$ 2.794
Series B Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Temporary equity shares authorized			29,457,450

Stockholders' Deficit

6 Months Ended

Jun. 30, 2021

Stockholders' Equity Note [Abstract]

Stockholders' Deficit

NOTE 5. STOCKHOLDERS’ DEFICIT

Authorized Shares

The Company amended its certificate of incorporation on November 20, 2020, such that the total number of shares of common stock authorized to be issued was increased to 50,500,000, and the total number of shares of preferred stock authorized to be issued was increased to 42,066,830, of which 711,203 were designated Series A convertible preferred stock, 11,898,177 were designated as Series

A-1

convertible preferred stock and 29,457,450 were designated as Series B convertible preferred stock. The certificate of incorporation was also amended for the reverse stock splits that became effective on June 23, 2021 and November 20, 2020, but there were no changes to the authorized shares as a result of the reverse stock split that became effective on June 23, 2021 (see Note 1).

See additional information in Note 9 related to an amendment to the Company’s certificate of incorporation effective upon the closing of the IPO on July 6, 2021.

Common Stock

As of June 30, 2021, the Company’s Amended and Restated Certificate of Incorporation authorized the issuance of 50,500,000 shares of common stock, $0.0001 par value per share. Each share of common stock was entitled to one voting right. The holders of common stock were entitled to elect two directors to the Board. Holders of common stock, voting together as a single class with the holders of preferred stock, could also designate an additional director to the Board. Common stock owners were entitled to dividends when funds are legally available and declared by the Board.

Common Stock Warrants

In June 2021, several holders of warrants to purchase the Company’s common stock exercised their warrants and purchased a total

of 137,446 shares of common stock at an exercise price of $4.47.

As of June 30, 2021 and December 31, 2020, the remaining outstanding warrants to purchase the Company’s common stock were comprised of the following:


	Equity Upon Exercise		Exercise Price		Expiration Dates		June 30, 3021	December 31, 2020
Warrants issued in 2014		Common Stock	$	4.47		3/21/2024 - 6/30/2025	72,178		83,726
Warrants issued in 2015		Common Stock	$	4.47		6/30/2025	109,908		209,690
Warrants issued in 2016		Common Stock	$	4.47		6/30/2025	34,396		34,396
Warrants issued in 2017		Common Stock	$	4.47		6/30/2025	31,765		57,881

Total Warrants							248,247		385,693