Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Mar. 14, 2022	Jun. 30, 2021
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
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	535 Boylston Street
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02116
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 Well Known Seasoned Issuer	No
Entity Voluntary Filers	No
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
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 70.4
Entity Common Stock, Shares Outstanding		21,974,302
Entity Central Index Key	0001781983
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Amendment Flag	false
Auditor Name	Ernst & Young LLP
Auditor Firm ID	42
Auditor Location	Iselin, New Jersey