CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities
Net loss	$ (16,660)	$ (23,332)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	179	259
Accretion related to marketable securities	95	169
Stock-based compensation	1,414	2,398
Loss from equity method investment	2,637	563
Changes in operating assets and liabilities:
Accounts receivable - related party	134	(3)
Prepaid and other current assets	(435)	(1,580)
Operating lease right-of-use asset	478	384
Other assets		98
Accounts payable	834	(602)
Accrued and other liabilities	(710)	738
Operating lease liability	(513)	(526)
Net cash used in operating activities	(12,547)	(21,434)
Cash flows from investing activities
Purchases of marketable securities	(29,420)	(4,709)
Maturities of marketable securities	6,990	24,797
Purchases of property and equipment	(4)
Net cash provided by (used in) investing activities	(22,434)	20,088
Cash flows from financing activities
Proceeds from issuance of common stock, net (includes $4,850 in aggregate gross proceeds from related parties for the three months ended March 31, 2021)		31,989
Proceeds from issuance of common stock in connection with at-the-market offering, net		11,817
Net cash provided by financing activities		43,806
Net increase (decrease) in cash and cash equivalents	(34,981)	42,460
Cash and cash equivalents at beginning of the period	63,458	16,455
Cash and cash equivalents at end of the period	28,477	$ 58,915
Supplemental disclosures of cash flow information
Purchases of property and equipment incurred but not paid	$ 251