Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities:
Net loss and comprehensive loss	$ (21,239)	$ (61,660)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation	9,706	11,262
Depreciation	335	321
Non-cash interest expense	568	601
Amortization of operating lease right-of-use assets	460	403
Changes in operating assets and liabilities:
Accounts receivable	(6,352)	(7,038)
Inventories	(13,343)	(1,561)
Milestone receivable from Pfizer	0	(100,000)
Prepaid expenses and other current assets	3,748	(3,916)
Amount due from related party	122	0
Other assets	392	112
Accounts payable	(2,698)	(8,676)
Accrued expenses and other current liabilities	(2,906)	(1,674)
Deferred revenue	(25,141)	70,491
Amounts due to Pfizer	6,681	9,071
Cost share advance from Pfizer	(25,831)	(18,285)
Operating lease liabilities	(502)	(425)
Amounts due to related parties	(11)	(504)
Other liabilities	6	(1,699)
Net cash used in operating activities	(76,005)	(113,177)
Cash flows from investing activities:
Purchases of marketable securities	(10,171)	(78,426)
Maturities of marketable securities	4,500	4,035
Purchases of property and equipment	(72)	0
Net cash used in investing activities	(5,743)	(74,391)
Cash flows from financing activities:
Proceeds from stock option exercises	1,191	4,135
Net cash provided by financing activities	1,191	4,135
Net change in cash, cash equivalents and restricted cash	(80,557)	(183,433)
Cash, cash equivalents and restricted cash, beginning of period	416,804	677,480
Cash, cash equivalents and restricted cash, end of period	336,247	494,047
Supplemental Disclosures of Non-Cash Financing Information:
Change in fair value of share-based awards recorded to additional paid-in capital	0	1,377
Reclassification of share-based compensation liabilities to additional paid-in capital upon settlement of awards	0	1,862
Stock options exercised receivable, included in prepaid expenses and other current assets	$ 0	$ 117