Unaudited Condensed Consolidated Statement of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Adjustments to reconcile net loss to net cash used in operating activities:
Net loss	$ (16,562)	$ (5,562)
Depreciation and amortization	203	251
Noncash lease expense	222	276
Paid-in-kind interest on convertible notes payable	0	306
Amortization of debt discount	0	1,250
Share-based compensation	1,510	57
Change in fair value of convertible notes payable derivative liabilities	0	635
Changes in operating assets and liabilities:
Accounts receivable	12	107
Prepaid expenses and other current assets	817	28
Accounts payable	132	(270)
Accrued expenses and other current liabilities	3,091	(120)
Operating lease liabilities	(182)	(283)
Net cash used in operating activities	(10,757)	(3,325)
Cash Flows from Investing Activities:
Purchase of property and equipment	(358)	(80)
Purchase of investments	(219,460)	0
Proceeds from sale of investments	160,001	0
Net cash used in investing activities	(59,817)	(80)
Cash Flows from Financing Activities:
Proceeds from exercise of stock warrants, net of issuance costs	16,257	0
Payments for Paycheck Protection Program loan	(908)	0
Proceeds from exercise of common stock options	287	0
Proceeds from convertible notes payable issuance and derivative liability	0	3,200
Repayments on finance lease obligations	(49)	(54)
Net cash provided by financing activities	15,587	3,146
Net decrease in cash and cash equivalents	(54,987)	(259)
Cash and cash equivalents- beginning of the period	389,705	6,285
Cash and cash equivalents - end of the period	$ 334,718	$ 6,026