Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 59,537	$ 107,146
Short-term investments		8,005
Receivables from collaborations		1,541
Prepaid expenses and other current assets	1,915	2,011
Total current assets	61,452	118,703
Restricted cash	270	440
Property and equipment, net	556	690
Operating lease right-of-use asset	2,478	5,754
Total assets	64,756	125,587
Current liabilities:
Accounts payable	3,650	1,994
Accrued and other liabilities	10,356	16,407
Total current liabilities	14,006	18,401
Noncurrent operating lease liability	1,666	4,815
Total liabilities	15,672	23,216
Commitments and contingencies (Note 5)
Convertible preferred stock; $0.0001 par value; 10,000 shares authorized as of December 31, 2021 and 2020; 1,000 and no shares issued and outstanding as of December 31, 2021 and 2020, respectively; $35,000 liquidation preference as of December 31, 2021 (Note 6)	40,702
Stockholders’ equity:
Common stock, $0.0001 par value, 200,000 shares authorized as of December 31, 2021 and 2020; 77,144 and 70,686 shares issued and outstanding as of December 31, 2021 and 2020, respectively	8	7
Additional paid-in capital	499,700	478,599
Accumulated deficit	(491,326)	(376,238)
Accumulated other comprehensive income		3
Total stockholders’ equity	8,382	102,371
Total liabilities, convertible preferred stock and stockholders' equity	$ 64,756	$ 125,587