Leases - Additional Information (Detail) $ in Millions	3 Months Ended
	Jul. 31, 2022 USD ($) ft²	Jul. 31, 2021 USD ($)
General and Administrative Expenses and Research and Development Expenses [Member]
Lessee Lease Description [Line Items]
Rent expense | $	$ 0.5	$ 0.4
Massachusetts [Member]
Lessee Lease Description [Line Items]
Lease agreement square feet	8,300
Massachusetts [Member] | Research Laboratory [Member]
Lessee Lease Description [Line Items]
Lease agreement square feet	500
United Kingdom [Member]
Lessee Lease Description [Line Items]
Lease agreement square feet	13,400
Lease description option to extend	option to terminate in April 2023. As of September 2022, the Company does not expect to exercise the option to terminate the leases.
Utah [Member]
Lessee Lease Description [Line Items]
Lease agreement square feet	6,200