Aprea Therapeutics (APRE) 10-Q 14 May 24 2024 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2024	May 14, 2024
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	001-39069
Entity Registrant Name	Aprea Therapeutics, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	84-2246769
Entity Address, Address Line One	3805 Old Easton Road
Entity Address, City or Town	Doylestown
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	18902
City Area Code	617
Local Phone Number	463-9385
Title of 12(b) Security	Common stock, par value $0.001 per share
Trading Symbol	APRE
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		5,430,215
Entity Central Index Key	0001781983
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 32,369,973	$ 21,606,820
Prepaid expenses and other current assets	698,864	914,275
Total current assets	33,068,837	22,521,095
Property and equipment, net	90,183	88,362
Restricted cash	40,986	40,717
Total assets	33,200,006	22,650,174
Current liabilities:
Accounts payable	1,318,385	1,670,369
Accrued expenses	1,498,286	2,186,262
Deferred grant revenue	148,405	528,974
Total current liabilities	2,965,076	4,385,605
Commitments and contingencies (Note 7)
Stockholders' equity:
Common stock, $0.001 par value, 400,000,000 shares authorized, 5,430,215 and 3,736,673 shares issued and outstanding at March 31, 2024 and December 31, 2023, respectively	5,430	3,736
Additional paid-in capital	350,438,045	335,644,204
Accumulated other comprehensive loss	(10,626,356)	(10,611,273)
Accumulated deficit	(310,893,252)	(308,083,161)
Total stockholders' equity	28,923,867	16,953,506
Total liabilities and stockholders' equity	33,200,006	22,650,174
Series A Convertible Preferred Stock
Convertible preferred stock:
Series A convertible preferred stock, $0.001 par value, 40,000,000 shares authorized; 56,227 shares issued and outstanding at March 31, 2024 and December 31, 2023	$ 1,311,063	$ 1,311,063

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	5,430,215	3,736,673
Common stock, shares outstanding	5,430,215	3,736,673
Series A Convertible Preferred Stock
Convertible preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	40,000,000	40,000,000
Convertible preferred stock, shares issued	56,227	56,227
Convertible preferred stock, shares outstanding	56,227	56,227

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Condensed Consolidated Statements of Operations and Comprehensive Loss
Grant revenue	$ 380,569
Operating expenses:
Research and development	1,600,373	$ 1,256,542
General and administrative	1,929,866	3,365,961
Total operating expenses	3,530,239	4,622,503
Loss from operations	(3,149,670)	(4,622,503)
Other income (expense):
Interest income, net	283,403	256,410
Foreign currency gain (loss)	56,176	(13,797)
Total other income	339,579	242,613
Net loss	(2,810,091)	(4,379,890)
Other comprehensive (loss) gain:
Foreign currency translation	(15,083)	61,956
Total comprehensive loss	$ (2,825,174)	$ (4,317,934)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.67)	$ (1.34)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.67)	$ (1.34)
Weighted-average common shares outstanding, basic (in shares)	4,198,326	3,260,484
Weighted-average common shares outstanding, diluted (in shares)	4,198,326	3,260,484

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity - USD ($)	Series A Convertible Preferred Stock Preferred Stock	Series A Convertible Preferred Stock	Common Stock ATM offering	Common Stock	Additional Paid-in capital ATM offering	Additional Paid-in capital	Accumulated other comprehensive loss	Accumulated deficit	ATM offering	Total
Temporary equity, beginning balance (in shares) at Dec. 31, 2022	56,227
Temporary equity, beginning balance at Dec. 31, 2022	$ 1,311,063
Temporary equity, ending balance (in shares) at Mar. 31, 2023	56,227
Temporary equity, ending balance at Mar. 31, 2023	$ 1,311,063
Equity, beginning balance at Dec. 31, 2022				$ 2,655		$ 330,060,836	$ (10,623,408)	$ (293,796,405)		$ 25,643,678
Equity, beginning balance (in shares) at Dec. 31, 2022				2,655,269
Increase (Decrease) in Stockholders' Equity
Issuance of common stock, net			$ 26	$ 1,050	$ 268,099	4,870,815			$ 268,125	4,871,865
Issuance of common stock, net (in shares)			26,302	1,050,000					26,302
Stock-based compensation						16,244				16,244
Foreign currency translation							61,956			61,956
Net Income (Loss)								(4,379,890)		(4,379,890)
Equity, ending balance at Mar. 31, 2023				$ 3,731		335,215,994	(10,561,452)	(298,176,295)		26,481,978
Equity, ending balance (in shares) at Mar. 31, 2023				3,731,571
Temporary equity, beginning balance (in shares) at Dec. 31, 2023	56,227	56,227
Temporary equity, beginning balance at Dec. 31, 2023	$ 1,311,063	$ 1,311,063
Temporary equity, ending balance (in shares) at Mar. 31, 2024	56,227	56,227
Temporary equity, ending balance at Mar. 31, 2024	$ 1,311,063	$ 1,311,063
Equity, beginning balance at Dec. 31, 2023				$ 3,736		335,644,204	(10,611,273)	(308,083,161)		16,953,506
Equity, beginning balance (in shares) at Dec. 31, 2023				3,736,673
Increase (Decrease) in Stockholders' Equity
Issuance of common stock, net				$ 1,688		14,708,017				14,709,705
Issuance of common stock, net (in shares)				1,687,712
Vesting of restricted stock units				$ 6		(6)
Vesting of restricted stock units (in shares)				5,830
Stock-based compensation						85,830				85,830
Foreign currency translation							(15,083)			(15,083)
Net Income (Loss)								(2,810,091)		(2,810,091)
Equity, ending balance at Mar. 31, 2024				$ 5,430		$ 350,438,045	$ (10,626,356)	$ (310,893,252)		$ 28,923,867
Equity, ending balance (in shares) at Mar. 31, 2024				5,430,215

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities:
Net loss	$ (2,810,091)	$ (4,379,890)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	6,157	410
Stockbased compensation	85,830	16,244
Foreign currency (gain) loss	(56,176)	13,797
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	213,641	344,056
Accounts payable	(350,256)	(16,727)
Accrued expenses	(644,427)	1,043,029
Deferred grant revenue	(380,569)
Net cash used in operating activities	(3,935,891)	(2,979,081)
Cash flows from investing activities:
Purchases of property and equipment	(7,978)
Net cash used in investing activities	(7,978)
Cash flows from financing activities:
Proceeds from issuance of common stock	15,999,598	5,788,918
Common stock issuance costs	(1,289,893)	(648,928)
Net cash provided by financing activities	14,709,705	5,139,990
Change in cash and cash equivalents and restricted cash	10,765,836	2,160,909
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(2,414)	48,158
Cash, cash equivalents and restricted cash-beginning of year	21,647,537	28,786,647
Cash, cash equivalents and restricted cash-end of period	32,410,959	30,995,714
Reconciliation of cash, cash equivalents and restricted cash
Cash and cash equivalents	32,369,973	30,995,714
Restricted cash	40,986
Total cash, cash equivalents and restricted cash	$ 32,410,959	$ 30,995,714

Nature of business and basis of

Nature of business and basis of presentation	3 Months Ended
	Mar. 31, 2024
Nature of business and basis of presentation
Nature of business and basis of presentation	1. Nature of business and basis of presentation Nature of business —Aprea Therapeutics, Inc. (the “Company”) is a clinical-stage biopharmaceutical company focused on precision oncology through synthetic lethality. The Company began principal operations in 2006 and is headquartered in Doylestown, Pennsylvania. Prior to the acquisition of Atrin Pharmaceuticals Inc. (“Atrin”) in May 2022, the Company was engaged in the clinical development of cancer therapeutics that reactivate the mutant p53 tumor suppressor protein. In December 2020, the Company announced that its pivotal Phase 3 myelodysplastic syndromes trial failed to meet its predefined primary endpoint of complete remission (CR) rate. Given these results, FDA feedback and the costs of continuing the APR-246 development program, the Company shifted focus of its activities to the assets acquired in the May 2022 acquisition of Atrin. The Company’s lead product candidate, ATRN-119, is a macrocyclic ATR inhibitor currently in a human clinical study for solid tumor indications. Basis of presentation and management plans Since its inception, the Company has devoted substantially all of its efforts to business planning, clinical operations, research and development, recruiting management, technical staff, raising capital and has financed its operations through the issuance of convertible preferred stock and common stock. The Company is subject to risks common to companies in the biopharmaceutical industry. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s intellectual property will be maintained, that any therapeutic products developed will obtain required regulatory approval or that any approved or consumer products will be commercially viable. Even if the Company’s development efforts are successful, it is uncertain when, if ever, the Company will generate significant product sales. The Company believes that the March 31, 2024 cash balance of approximately $32.4 million will be sufficient to fund the Company’s operations into the third quarter of 2025. In the event that additional funds are not available thereafter, management would expect to significantly reduce expenditures to conserve cash, which would involve scaling back or curtailing new development activity.

Summary of significant accounti

Summary of significant accounting policies	3 Months Ended
	Mar. 31, 2024
Summary of significant accounting policies
Summary of significant accounting policies	2. Summary of significant accounting policies The Company's complete listing of significant accounting policies are described in Note 2 to the Company's audited consolidated financial statements as of December 31, 2023 included in its annual report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”). Principles of consolidation Unaudited interim consolidated financial statements The unaudited interim consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements, and in management’s opinion, include all adjustments, consisting of only normal recurring adjustments, necessary for the fair presentation of the financial information for the interim periods have been made. The results of operations for the three months ended March 31, 2024 are not necessarily indicative of the results to be expected for the full fiscal year or any future period. Use of estimates Foreign currency and currency translation Cash and cash equivalents— Restricted cash— Fair value of financial instruments ● Level 1 inputs: Quoted prices in active markets for identical assets or liabilities. ● Level 2 inputs: Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable, such as quoted market prices, interest rates and yield curves. ● Level 3 inputs: Unobservable inputs developed using estimates or assumptions developed by the Company, which reflect those that a market participant would use in pricing the asset or liability. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in 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 Company’s financial instruments consist of cash, cash equivalents, restricted cash, accounts payable and accrued expenses. The carrying amount of accounts payable and accrued expenses is considered a reasonable estimate of fair value due to the short-term maturity. Series A Convertible Preferred Stock Accounting for leases The Company has elected not to separate lease and non-lease components as a single component. Operating leases are recognized on the balance sheet as right of use (ROU) lease assets, lease liabilities current and lease liabilities non-current. Fixed rents are included in the calculation of the lease balances while variable costs paid for certain operating and pass-through costs are excluded. Lease expense is recognized over the expected term on a straight-line basis. The Company has also elected the short-term lease exemption for all leases with an original term of less than 12 months. Revenue recognition 958, Not - not 606, not ​ Stock-based compensation For stock-based awards granted to non-employees, compensation expense is recognized over the period during which services are rendered by such non-employees until completed in accordance with ASC 718. The Company estimates the fair value of each stock option grant on the date of grant using the Black Scholes option pricing model, which uses as inputs the fair value of the Company’s common stock and assumptions the Company makes for the volatility of its common stock, the expected term of its stock options, the risk-free interest rate for a period that approximates the expected term of its stock options and its expected dividend yield. The Company elects to account for forfeitures when they occur. The Company also awards restricted stock units (“RSUs”) to employees and directors. RSUs are generally subject to forfeiture if employment terminates prior to the completion of the vesting restrictions. The Company expenses the cost of the RSUs, which is determined to be the fair market value of the shares of common stock underlying the RSUs at the date of grant, ratably over the period during which the vesting restrictions lapse. ​ Net loss per share The following table sets forth the potentially dilutive securities that have been excluded from the calculation of diluted net loss per share because to include them would be anti-dilutive (in common stock equivalent shares): ​ ​ ​ ​ ​ ​ ​ Three months ended March 31, ​ 2024 2023 Convertible preferred stock (as converted) ​ 28,112 ​ 28,112 Options to purchase common stock 596,466 551,886 Warrants to purchase common stock 2,194,788 — Unvested restricted stock units ​ 28,130 ​ 30,277 Total shares of common stock equivalents 2,847,496 610,275 ​ Recently issued accounting pronouncements— From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that the Company adopts as of the specified effective date. Management does not believe that any recently issued, but not yet effective accounting pronouncements, if adopted, would have a material impact on the accompanying financial statements.

Leases

Leases	3 Months Ended
	Mar. 31, 2024
Leases
Leases	3. Leases The Company is party to one operating lease for office and laboratory space. The Company’s finance leases are immaterial both individually and in the aggregate. The Company has elected to apply the short-term lease exception to all leases of one year or less. Rent expense for each of the three months ended March 31, 2024 and 2023 was $19,998, which is included in operating expenses. The Company has an annual operating lease for office and laboratory space in Doylestown, Pennsylvania which was renewed for 2024 and is currently set to expire on December 31, 2024. Rent expense under this lease is $110,000 annually and the Company has applied the short-term exception to this lease. The Company has no lease obligations beyond 2024.

Accrued expenses

Accrued expenses	3 Months Ended
	Mar. 31, 2024
Accrued expenses
Accrued expenses	4. Accrued expenses Accrued expenses consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 Professional fees ​ $ 144,313 ​ $ 138,601 Compensation, severance and benefits ​ 285,207 ​ 1,016,960 Research and development ​ 859,982 ​ 856,575 Other ​ 208,784 ​ 174,126 Total accrued expenses ​ $ 1,498,286 ​ $ 2,186,262 ​

Stockholders' equity

Stockholders' equity	3 Months Ended
	Mar. 31, 2024
Stockholders' equity
Stockholders' equity	5. Stockholders’ equity The total number of shares of all classes of capital stock that the Company is authorized to issue is 440,000,000 shares, consisting of 400,000,000 shares of common stock, par value $0.001 per share and 40,000,000 shares of preferred stock, par value $0.001 per share. ​ Series A Preferred Stock ​ As of March 31, 2024, a total of 56,227 shares of Series A Preferred Stock remained outstanding, which are convertible into 28,112 shares of common stock. ​ Common Stock The holders of common stock are entitled to one vote for each share of common stock. In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company, after the payment or provision for payment of all debts and liabilities of the Company, the holders of common stock shall be entitled to share in the remaining assets of the Company available for distribution, if any. Shelf Registration Statement On November 12, 2020, the Company filed a universal shelf registration statement with the SEC for the issuance of common stock, preferred stock, warrants, rights, debt securities and units up to an aggregate of $350.0 million (the “2020 Shelf Registration Statement”). On November 30, 2020, the 2020 Shelf Registration Statement was declared effective by the SEC and on November 30, 2023, the 2020 Shelf Registration Statement expired. The 2020 Shelf Registration Statement included an at-the-market offering program with SVB Leerink LLC (the “SVB ATM Program”) and the Company filed a Prospectus Supplement dated September 2, 2022, for the sale of up to $14,744,728 of shares of the Company’s common stock pursuant to its ATM offering program. The Company agreed to pay a commission of 3% of the gross proceeds of any common stock sold in connection with the SVB ATM Program. During the three months ended March 31, 2023, the Company issued and sold 26,302 shares of common stock under the ATM offering program resulting in net proceeds to the Company of approximately $0.3 million after deducting approximately $8,000 in issuance costs. The SVB ATM Program has terminated and is no longer effective. In February 2023, the Company issued and sold 1,050,000 shares of common stock at a public offering price of $5.25 per share pursuant to the 2020 Shelf Registration Statement resulting in net proceeds to the Company of approximately $4.9 million, after deducting underwriting discounts and offering expenses of approximately $0.6 million. On January 26, 2024, the Company filed a new shelf registration statement (the “2024 Shelf Registration Statement”) with the SEC for issuance of common stock, preferred stock, warrants, rights, debt securities and units up to an aggregate of $150 million, including a prospectus for the sale of $1 million of shares of our common stock under the ATM Agreement, as defined below, which was declared effective on February 2, 2024. The Company subsequently filed a prospectus supplement to the 2024 Shelf Registration Statement for the sale of up to million of shares of common stock pursuant to the ATM Agreement. On January 26, 2024, the Company entered into an At the Market Offering Agreement (the “ATM Agreement”) with H.C. Wainright & Co., LLC (“HCW”). Pursuant to the ATM Agreement and the prospectus supplement filed in connection therewith, the Company was able, from time to time, in its sole discretion, to issue and sell through HCW, acting as sales agent and/or principal, up to million of shares of common stock. The Company did not make any sales under the ATM Agreement and in March 2024, the Company terminated the ATM Agreement with HCW. March 2024 Private Placement On March 11, 2024, the Company entered into a securities purchase agreement with certain purchasers (the “Purchasers”) pursuant to which the Company agreed to issue and sell to the Purchasers in a private placement offering exempt from registration under the Securities Act of 1933, as amended, or the Securities Act, and the Purchasers agreed to purchase from the Company (i) 1,687,712 shares of the Company’s common stock at a purchase price of $7.29 per share (the “Shares”), (ii) pre-funded common stock purchase warrants to purchase an aggregate of up to 507,076 shares of the Company’s common stock at an exercise price of $0.001 per share (the “Pre-Funded Shares”), (iii) tranche A common stock purchase warrants to purchase up to 1,097,394 shares of the Company’s common stock at an exercise price of $7.29 per share (the “Tranche A Warrants”), and (iv) tranche B common stock purchase warrants to purchase up to 1,097,394 shares of the Company’s common stock at an exercise price of $9.1125 per share (the “Tranche B Warrants”). The Tranche A Warrants will be exercisable until the earlier of (i) the three-year anniversary of issuance and (ii) 30 days after the Company announces the recommended Phase 2 dose for ATRN-119, and, following such announcement, the daily volume weighted average price of the Company’s common stock equals or exceeds $14.58 for 30 consecutive trading days. The Tranche B Warrants will be exercisable until the earlier of (i) the five-year anniversary of issuance and (ii) 30 days after the Company announces the recommended Phase 2 dose for APR-1051 and, following such announcement, the daily volume weighted average price of the Company’s common stock equals or exceeds $18.225 for 30 consecutive trading days. To the extent that the exercise of a Tranche A Warrant or Tranche B Warrant would result in the holder beneficially owning greater than 4.99% (or, at the election of the holder, greater than 9.99%) of the Company’s outstanding common stock immediately following such exercise, the holder will instead receive pre-funded warrants in substantially the same form as the pre-funded warrants issued at closing. Each share of the Company’s common stock was sold at an offering price of $7.29 and each pre-funded common stock purchase warrant was sold at an offering price of $7.29. The aggregate upfront gross proceeds from the issuance of common stock and pre-funded common stock purchase warrants totaled approximately $16.0 million, before deducting placement agent fees and offering costs of approximately $1.3 million. The gross proceeds from potential future warrant cash exercises are expected to be up to approximately $18.0 million, before deducting placement agent fees. In April 2024, we registered on Form S-3 the resale of the Shares, the Pre-Funded Shares and the shares underlying the Tranche A Warrants and Tranche B Warrants. We evaluated the terms of the warrants issued and determined that they should be classified as equity instruments within additional paid-in capital. As of March 31, 2024, none of the pre-funded warrants, Tranche A Warrants or Tranche B Warrants have been exercised. Stock-Based Compensation Expense The Company recorded stock-based compensation expense of $85,830 and $16,244 for the three months ended March 31, 2024 and 2023, respectively. ​

Income taxes

Income taxes	3 Months Ended
	Mar. 31, 2024
Income taxes
Income taxes	6. Income Taxes ​ The Company has no income tax expense due to operating losses incurred for the three months ended March 31, 2024 and 2023. The Company has provided a valuation allowance for the full amount of the net deferred tax assets as, based on all available evidence, it is considered more likely than not that all the recorded deferred tax assets will not be realized in a future period. Realization of the future tax benefits is dependent on may factors, including the Company’s ability to generate taxable income within the net operating loss carryforward period. Under the provisions of the U.S. Internal Revenue Code and Sweden tax law, certain substantial changes in the Company’s ownership, including a sale of the Company or significant changes in ownership due to sales of equity, may have limited, or may limit in the future, the amount of net operating loss carryforwards that could be used annually to offset future taxable income. For U.S. and Swedish income tax purposes, the Company has not completed a study to assess whether a change of control has occurred or whether there have been changes of control since the Company’s formation due to the complexity and cost associated with such study and because there could be additional changes of control in the future. As a result, the Company is not able to estimate the effect of the change in control, if any, on the Company’s ability to utilize U.S. or Swedish net operating losses or other tax attribute carryforwards in the future. For Swedish income tax purposes, the Company’s net operating losses may be subject to limitations in accordance with the country’s group contribution restriction laws. ​ The Company files tax returns in Sweden, the United States, Massachusetts and Pennsylvania. Income tax returns prior to 2020 in the United States and Massachusetts are no longer subject to examination and income tax returns prior to 2017 are no longer subject to examination in Sweden. The Company is not currently under examination by the IRS or any other jurisdictions for any tax years. As tax law is complex and often subject to varied interpretations, it is uncertain whether some of the Company’s tax positions will be sustained upon examination. Tax liabilities associated with uncertain tax positions represent unrecognized tax benefits, which arise when the estimated benefit recorded in the Company’s financial statements differs from the amounts taken or expected to be taken in a tax return because of the uncertainties described above. Substantially all of these unrecognized tax benefits, if recognized, would benefit the Company’s effective income tax rate. As of March 31, 2024 and December 31, 2023, the Company had approximately $0.1 million of liabilities related to uncertain tax positions. As the Company’s uncertain tax positions can be offset by available net operating losses, the Company did not recognize interest and penalties for 2024 and 2023.

Commitments and contingencies

Commitments and contingencies	3 Months Ended
	Mar. 31, 2024
Commitments and contingencies.
Commitments and contingencies	7. Commitments and contingencies The Company records a provision for contingent losses when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. As of March 31, 2024, the Company has not recorded a provision for any contingent losses.

Summary of significant accoun_2

Summary of significant accounting policies (Policies)	3 Months Ended
	Mar. 31, 2024
Summary of significant accounting policies
Principles of consolidation	Principles of consolidation
Unaudited interim consolidated financial statements	Unaudited interim consolidated financial statements The unaudited interim consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements, and in management’s opinion, include all adjustments, consisting of only normal recurring adjustments, necessary for the fair presentation of the financial information for the interim periods have been made. The results of operations for the three months ended March 31, 2024 are not necessarily indicative of the results to be expected for the full fiscal year or any future period.
Use of estimates	Use of estimates
Foreign currency and currency translation	Foreign currency and currency translation
Cash and cash equivalents and restricted cash	Cash and cash equivalents— Restricted cash—
Fair value of financial instruments	Fair value of financial instruments ● Level 1 inputs: Quoted prices in active markets for identical assets or liabilities. ● Level 2 inputs: Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable, such as quoted market prices, interest rates and yield curves. ● Level 3 inputs: Unobservable inputs developed using estimates or assumptions developed by the Company, which reflect those that a market participant would use in pricing the asset or liability. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in 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 Company’s financial instruments consist of cash, cash equivalents, restricted cash, accounts payable and accrued expenses. The carrying amount of accounts payable and accrued expenses is considered a reasonable estimate of fair value due to the short-term maturity.
Series A Convertible Preferred Stock	Series A Convertible Preferred Stock
Accounting for leases	Accounting for leases The Company has elected not to separate lease and non-lease components as a single component. Operating leases are recognized on the balance sheet as right of use (ROU) lease assets, lease liabilities current and lease liabilities non-current. Fixed rents are included in the calculation of the lease balances while variable costs paid for certain operating and pass-through costs are excluded. Lease expense is recognized over the expected term on a straight-line basis. The Company has also elected the short-term lease exemption for all leases with an original term of less than 12 months.
Revenue recognition	Revenue recognition 958, Not - not 606, not
Stock-based compensation	Stock-based compensation For stock-based awards granted to non-employees, compensation expense is recognized over the period during which services are rendered by such non-employees until completed in accordance with ASC 718. The Company estimates the fair value of each stock option grant on the date of grant using the Black Scholes option pricing model, which uses as inputs the fair value of the Company’s common stock and assumptions the Company makes for the volatility of its common stock, the expected term of its stock options, the risk-free interest rate for a period that approximates the expected term of its stock options and its expected dividend yield. The Company elects to account for forfeitures when they occur. The Company also awards restricted stock units (“RSUs”) to employees and directors. RSUs are generally subject to forfeiture if employment terminates prior to the completion of the vesting restrictions. The Company expenses the cost of the RSUs, which is determined to be the fair market value of the shares of common stock underlying the RSUs at the date of grant, ratably over the period during which the vesting restrictions lapse.
Net loss per share	Net loss per share The following table sets forth the potentially dilutive securities that have been excluded from the calculation of diluted net loss per share because to include them would be anti-dilutive (in common stock equivalent shares): ​ ​ ​ ​ ​ ​ ​ Three months ended March 31, ​ 2024 2023 Convertible preferred stock (as converted) ​ 28,112 ​ 28,112 Options to purchase common stock 596,466 551,886 Warrants to purchase common stock 2,194,788 — Unvested restricted stock units ​ 28,130 ​ 30,277 Total shares of common stock equivalents 2,847,496 610,275
Recently issued accounting pronouncements	Recently issued accounting pronouncements— From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that the Company adopts as of the specified effective date. Management does not believe that any recently issued, but not yet effective accounting pronouncements, if adopted, would have a material impact on the accompanying financial statements.

Summary of significant accoun_3

Summary of significant accounting policies (Tables)	3 Months Ended
	Mar. 31, 2024
Summary of significant accounting policies
Schedule of potentially dilutive securities excluded from calculation of diluted net loss per share	The following table sets forth the potentially dilutive securities that have been excluded from the calculation of diluted net loss per share because to include them would be anti-dilutive (in common stock equivalent shares): ​ ​ ​ ​ ​ ​ ​ Three months ended March 31, ​ 2024 2023 Convertible preferred stock (as converted) ​ 28,112 ​ 28,112 Options to purchase common stock 596,466 551,886 Warrants to purchase common stock 2,194,788 — Unvested restricted stock units ​ 28,130 ​ 30,277 Total shares of common stock equivalents 2,847,496 610,275

Accrued expenses (Tables)

Accrued expenses (Tables)	3 Months Ended
	Mar. 31, 2024
Accrued expenses
Schedule of accrued expenses	​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2024 ​ 2023 Professional fees ​ $ 144,313 ​ $ 138,601 Compensation, severance and benefits ​ 285,207 ​ 1,016,960 Research and development ​ 859,982 ​ 856,575 Other ​ 208,784 ​ 174,126 Total accrued expenses ​ $ 1,498,286 ​ $ 2,186,262 ​

Nature of business and basis _2

Nature of business and basis of presentation (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Nature of business and basis of presentation
Cash balance	$ 32,369,973	$ 21,606,820	$ 30,995,714

Summary of significant accoun_4

Summary of significant accounting policies - Restricted cash (Details)	Mar. 31, 2024 USD ($)
Summary of significant accounting policies
Restricted cash	$ 40,986

Summary of significant accoun_5

Summary of significant accounting policies - Potentially dilutive securities (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Potentially dilutive securities
Total shares of common stock equivalents	2,847,496	610,275
Convertible preferred stock (as converted)
Potentially dilutive securities
Total shares of common stock equivalents	28,112	28,112
Employee Stock Option [Member]
Potentially dilutive securities
Total shares of common stock equivalents	596,466	551,886
Warrants to purchase common stock
Potentially dilutive securities
Total shares of common stock equivalents	2,194,788
Unvested restricted stock units
Potentially dilutive securities
Total shares of common stock equivalents	28,130	30,277

Leases - Summary (Details)

Leases - Summary (Details)	3 Months Ended
	Mar. 31, 2024 USD ($) lease	Mar. 31, 2023 USD ($)
Leases
Number of operating leases | lease	1
Rent expense	$ 19,998	$ 19,998
Annual base rent	$ 110,000

Accrued expenses (Details)

Accrued expenses (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Accrued expenses
Professional fees	$ 144,313	$ 138,601
Compensation, severance and benefits	285,207	1,016,960
Research and development	859,982	856,575
Other	208,784	174,126
Total accrued expenses	$ 1,498,286	$ 2,186,262

Stockholders' equity (Details)

Stockholders' equity (Details)			1 Months Ended	3 Months Ended
	Mar. 11, 2024 USD ($) $ / shares shares	Nov. 12, 2020 USD ($)	Feb. 28, 2023 USD ($) $ / shares shares	Mar. 31, 2024 USD ($) Vote $ / shares shares	Mar. 31, 2023 USD ($) shares	Jan. 26, 2024 USD ($)	Dec. 31, 2023 $ / shares shares
Common stock
Stock, shares authorized | shares				440,000,000
Common stock, shares authorized | shares				400,000,000			400,000,000
Common stock, par value (in dollars per share) | $ / shares				$ 0.001			$ 0.001
Preferred stock, shares authorized | shares				40,000,000
Preferred stock, par value (in dollars per share) | $ / shares				$ 0.001
Common stock issuable upon conversion (in shares) | shares				28,112
Number of voting rights per common share | Vote				1
Stock based compensation expense				$ 85,830	$ 16,244
Shelf Registration Statement
Proceeds from issuance of common stock				15,999,598	5,788,918
Common stock issuance costs				1,289,893	$ 648,928
March 2024 Private Placement
Warrant exercises				$ 0
Series A Convertible Preferred Stock
Common stock
Convertible preferred stock, shares outstanding | shares				56,227			56,227
March 2024 Private Placement | Purchasers | Securities purchase agreement
Shelf Registration Statement
Shares issued | shares	1,687,712
Common stock issuance costs	$ 1,300,000
March 2024 Private Placement
Offering price per share | $ / shares	$ 7.29
Warrants to purchase of shares | shares	507,076
Common stock with an exercise price | $ / shares	$ 0.001
Percentage of outstanding shares	4.99%
Proceeds from sale of common stock in a private placement	$ 16,000,000
Expected gross proceeds from potential future warrants cash exercise	$ 18,000,000
March 2024 Private Placement | Purchasers | Securities purchase agreement | At the election of holder
March 2024 Private Placement
Percentage of outstanding shares	9.99%
March 2024 Private Placement | Purchasers | Securities purchase agreement | Pre-funded Warrants
March 2024 Private Placement
Offering price per share | $ / shares	$ 7.29
March 2024 Private Placement | Purchasers | Securities purchase agreement | Tranche A Warrants (Pre-funded Warrants Exercise Price 7.29 Per Share)
March 2024 Private Placement
Warrants to purchase of shares | shares	1,097,394
Common stock with an exercise price | $ / shares	$ 7.29
Stock issuance anniversary period	3 years
Number of days after announcement of Phase 2 dose for ATRN-119	30 days
Volume weighted average price | $ / shares	$ 14.58
Number of consecutive trading days	30 days
March 2024 Private Placement | Purchasers | Securities purchase agreement | Tranche B Warrants (Pre-funded Warrants Exercise Price 9.1125 Per Share)
March 2024 Private Placement
Common stock with an exercise price | $ / shares	$ 9.1125
Stock issuance anniversary period	5 years
Number of days after announcement of Phase 2 dose for ATRN-119	30 days
Volume weighted average price | $ / shares	$ 18.225
2020 Shelf Registration Statement
Shelf Registration Statement
Maximum amount to be issued under universal shelf registration statement		$ 350,000,000
2020 Shelf Registration Statement | Common Stock
Shelf Registration Statement
Shares issued | shares			1,050,000
Issue price per share | $ / shares			$ 5.25
Proceeds from issuance of common stock			$ 4,900,000
Common stock issuance costs			$ 600,000
ATM offering
Common stock
Commission payable as a percentage of gross proceeds from sale of common stock under ATM offering		3%
Shelf Registration Statement
Maximum amount to be issued under at-the-market offering program		$ 14,744,728
Shares issued | shares					26,302
Proceeds from issuance of common shares					$ 300,000
Common stock issuance costs					$ 8,000
2024 Shelf Registration Statement
Shelf Registration Statement
Maximum amount to be issued under universal shelf registration statement						$ 150,000,000
Maximum amount to be issued under at-the-market offering program						1,000,000
Maximum amount to be issued under at-the-market offering program, supplement						2,000,000
2024 ATM offering | HCW
Shelf Registration Statement
Maximum amount to be issued under at-the-market offering program						$ 2,000,000

Income taxes - Narrative (Detai

Income taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Income taxes
Income tax expense	$ 0	$ 0
Uncertain tax positions	$ 0.1		$ 0.1

Commitments and contingencies (

Commitments and contingencies (Details)	3 Months Ended
	Mar. 31, 2024 USD ($)
Commitments and contingencies.
Provision for contingent losses	$ 0

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (2,810,091)	$ (4,379,890)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Mar. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false