Reportable segment disclosure - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Research and Development expense	$ 28,615	$ 23,662	$ 83,790	$ 70,438
Sales & Marketing	1,178	519	1,858	2,263
General & Administrative	7,259	7,220	21,348	23,667
Total personnel expenses	37,051	31,401	106,997	96,368
Viaskin Peanut Segment
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Sales & Marketing	1,178	519	1,859	2,263
General & Administrative	7,259	7,220	21,348	23,667
Total personnel expenses	37,051	31,401	106,997	96,368
Viaskin Peanut Segment | Clinical studies
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Research and Development expense	10,130	12,929	33,190	34,157
Viaskin Peanut Segment | BLA & Regulatory
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Research and Development expense	3,296	2,031	6,979	5,121
Viaskin Peanut Segment | Medical Affairs & Other Medical
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Research and Development expense	2,256	2,156	6,223	6,446
Viaskin Peanut Segment | Research & Innovation
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Research and Development expense	364	322	1,450	1,087
Viaskin Peanut Segment | Manufacturing & Supply and Quality
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Research and Development expense	$ 12,569	$ 6,224	$ 35,948	$ 23,627