Nature of business and basis of presentation (Details)	1 Months Ended
Sep. 30, 2019 $ / shares	Jun. 30, 2021 USD ($) $ / shares	Dec. 31, 2020 USD ($) $ / shares
Cash balance \| $		$ 69,803,845	$ 89,017,686
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001
Aprea Therapeutics AB
Common stock, par value (in dollars per share)	$ 0.11
Convertible preferred stock \| Aprea Therapeutics AB
Conversion ratio	1
Common Stock \| Aprea Therapeutics AB
Conversion ratio	1

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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