FORM 10-K ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the year ended December 31, 2025 OR Securities registered pursuant to Section 12(b) of the Act: Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.Yes☐No☒ Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes☐No☒ Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or forsuch shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes☒No☐ Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter)during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).Yes☒No☐ Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See thedefinitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act. If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accountingstandards provided pursuant to Section 13(a) of the Exchange Act.☐ Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting underSection 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.☐ If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error topreviously issued financial statements.☐ Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executiveofficers during the relevant recovery period pursuant to §240.10D-1(b).☐ Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes☐No☒ The aggregate market value of the voting and non-voting common equity held by non-affiliates of the registrant as of June 30, 2025 was approximately $8.6 million. There were 11,452,452 shares of the registrant’s common stock, $0.001 par value, outstanding as of March 16, 2026. DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s definitive proxy statement for its 2025 Annual Meeting of Stockholders (the “Proxy Statement”), to be filed within 120 days of the registrant’s fiscal year endedDecember 31, 2025, are incorporated by reference in Part III of this Annual Report on Form 10-K. Except with respect to information specifically incorporated by reference in this Annual Report onForm 10-K, the Proxy Statement is not deemed to be filed as part of this Annual Report on Form 10-K. Aprea Therapeutics, Inc.Annual Report on Form 10-KFor the Year Ended December 31, 2025 Table of Contents PART I Item 1. BusinessItem 1A. Risk FactorsItem 1B. Unresolved Staff CommentsItem 1C. CybersecurityItem 2. PropertiesItem 3. Legal ProceedingsItem 4. Mine Safety Disclosures PART II PART III PART IV CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS This Annual Report on Form 10-K includes statements that are, or may be deemed, “forward-looking statements.” Insome cases, these forward-looking statements can be identified by the use of forward-looking terminology, including theterms “believes,” “estimates,” “anticipates,” “expects,” “plans,” “intends,” “may,” “designed,” “would,” “could,”“might,” “will,” “should,” “approximately” or, in each case, their negative or other variations thereon or comparableterminology, although not all forward-looking statements contain these words. They appear in a number of placesthroughout this Annual Report on Form 10-K and include statements regarding our current intentions, beliefs,projections, outlook, analyses or current expectations concerning, among other things, our ongoing and planned clinicaltrials, including for APR-1051 and ATRN-119, our ongoing and planned development, prospects for commercialization,and market uptake of our potential product candidates, the strength and breadth of our intellectual property, the timing ofand our ability to make regulatory filings and obtain and maintain regulatory approvals for o