Summary of significant accounting policies - Additional Information (Detail)		12 Months Ended
	Jul. 06, 2021 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) Segment	Dec. 31, 2020 USD ($)
Financing Sources [Line Items]
Re-measurement gain (loss)		$ (6,000)	$ 121,000
Number of reportable segments | Segment		1
Revenue from collaborations		$ 4,359,000
Revenue		0
Property and equipment, net		$ 6,180,000	8,007,000
Cash equivalent qualification, description		The Company considers all highly liquid investments purchased with original maturities of 90 days or less at acquisition to be cash equivalents.
Restricted cash		$ 164,000	$ 560,000
Investments, maturity period		1 year 6 months	1 year 6 months
Other than temporary impairment losses, investments		$ 0	$ 0
Impairment of long lived assets		0	0
Royalties due		0
Expenses on milestone payments		500,000
Dividends, common stock, cash		$ 0
Expected dividend yield		0.00%
Percentage of expected average remaining working lives of employees		10.00%
Research and Development
Financing Sources [Line Items]
Expenses on milestone payments			4,500,000
Follow-on Offering
Financing Sources [Line Items]
Stock issued during the period new issues shares | shares	4,400,000
Sale of stock issue price per share | $ / shares	$ 19.00
Sale of stock net consideration received on the transaction	$ 7,770,000
Follow-on Offering | Other Noncurrent Assets [Member]
Financing Sources [Line Items]
Deferred offering costs		$ 0	0
US
Financing Sources [Line Items]
Property and equipment, net		5,000,000.0	6,600,000
Belgium
Financing Sources [Line Items]
Property and equipment, net		$ 1,200,000	$ 1,400,000