CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (UNAUDITED)
Revenue from collaboration and licensing	$ 2,230	$ 3,874	$ 6,421	$ 14,553
Revenue from Contract with Customer, Product and Service [Extensible List]	hook:CollaborationAndLicensingMember	hook:CollaborationAndLicensingMember	hook:CollaborationAndLicensingMember	hook:CollaborationAndLicensingMember
Operating expenses:
Research and development	$ (18,286)	$ (20,698)	$ (51,053)	$ (60,434)
General and administrative	(4,937)	(4,342)	(14,935)	(13,746)
Total operating expenses	(23,223)	(25,040)	(65,988)	(74,180)
Loss from operations	(20,993)	(21,166)	(59,567)	(59,627)
Other income (expense):
Grant income	2,081	2,487	5,926	7,196
Interest income	535	7	724	21
Interest expense	(105)	(234)	(579)	(671)
Other income and (expenses), net	202	(1,133)	893	(1,348)
Total other income, net	2,713	1,127	6,964	5,198
Net loss before tax	(18,280)	(20,039)	(52,603)	(54,429)
Income tax expense	0	(1)	(1)	(1)
Net loss	(18,280)	(20,040)	(52,604)	(54,430)
Other comprehensive loss:
Foreign currency translation gain (loss), net of tax	(1,367)	471	(2,855)	288
Comprehensive loss	$ (19,647)	$ (19,569)	$ (55,459)	$ (54,142)
Net loss per share - basic	$ (0.25)	$ (0.61)	$ (0.83)	$ (1.66)
Net loss per share - diluted	$ (0.25)	$ (0.61)	$ (0.83)	$ (1.66)