Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Jul. 31, 2022	Apr. 30, 2022
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid clinical expenses	$ 6,709	$ 8,404
Other prepaid expenses	2,334	2,234
Interest and other receivables	463	888
VAT receivable	1,578	1,821
Total prepaid expenses and other current assets	$ 11,084	$ 13,347