Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Apr. 30, 2022	Apr. 30, 2021
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid clinical expenses	$ 8,404	$ 2,155
Other prepaid expenses	2,234	1,461
Interest and other receivables	888	940
VAT receivable	1,821	361
Total prepaid expenses and other current assets	$ 13,347	$ 4,917