CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities
Net loss	$ (30,923)	$ (9,339)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	18	18
Non-cash lease expense	54
Amortization and accretion of discounts on short-term investments	456	(24)
Stock compensation expense	8,103	646
Changes in operating assets and liabilities:
Unbilled grant receivables		(48)
Accrued interest	(19)	(49)
Prepaid expenses and other current assets	1,735	(284)
Accounts payable, accrued expenses and amount due to related party	1,650	(1,463)
Net cash used in operating activities	(18,926)	(10,543)
Cash flows from investing activities
Purchase of property and equipment	(75)
Purchase of short-term investments	(30,098)	(21,161)
Maturities of short-term investments	95,000	35,000
Net cash provided by investing activities	64,827	13,839
Cash flows from financing activities
Effect of exchange rate changes on cash and cash equivalents	83
Net increase in cash and cash equivalents	45,984	3,296
Cash and cash equivalents at beginning of period	122,661	61,084
Cash and cash equivalents at end of period	168,645	64,380
Non-cash investing and financing activities
Unrealized gain on available-for-sale securities	42	$ 176
Right-of-use assets obtained in exchange for operating lease liability	$ 3,099