Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands		3 Months Ended
		Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net loss		$ (61,660)	$ (32,860)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation		11,262	7,812
Depreciation and amortization	[1]	724	551
Non-cash interest expense		601	0
Foreign currency transaction gain		0	(3,569)
Other		0	94
Changes in operating assets and liabilities:
Accounts receivable		(7,038)	0
Inventory		(1,561)	0
Milestone receivable from Pfizer		(100,000)	0
Prepaid expenses and other current assets		(3,916)	(1,101)
Other assets		112	0
Accounts payable		(8,676)	(9,946)
Interest payable (related party)		0	9
Accrued expenses and other current liabilities		(1,674)	(254)
Deferred revenue		70,491	(23,333)
Amounts due to Pfizer		9,071	0
Cost share advance from Pfizer		(18,285)	0
Operating lease liabilities		(425)	(356)
Amounts due to related parties		(504)	114
Other liabilities		(1,699)	855
Net cash used in operating activities		(113,177)	(61,984)
Cash flows from investing activities:
Purchases of marketable securities		(78,426)	(14,973)
Maturities of marketable securities		4,035	3,000
Purchases of property and equipment		0	(151)
Net cash used in investing activities		(74,391)	(12,124)
Cash flows from financing activities:
Proceeds from related party debt financing		0	80,000
Proceeds from stock option exercises		4,135	2,190
Net cash provided by financing activities		4,135	82,190
Net change in cash, cash equivalents and restricted cash		(183,433)	8,082
Cash, cash equivalents and restricted cash, beginning of period		677,480	78,018
Cash, cash equivalents and restricted cash, end of period		494,047	86,100
Non-cash financing activities:
Change in fair value of share-based awards recorded to additional paid-in capital		1,377	0
Reclassification of share-based compensation liabilities to additional paid-in capital upon settlement of awards		1,862	0
Stock options exercised receivable, included in prepaid expenses and other current assets		$ 117	$ 0

[1] Includes amortization of operating lease right-of-use assets.