Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
CURRENT ASSETS
Cash and cash equivalents	$ 24,665	$ 90,095
Marketable securities	87,763	56,178
Prepaid expenses and other current assets	5,086	3,516
Total current assets	117,514	149,789
Restricted cash	1,837	1,842
Property and equipment, net	4,916	5,642
Operating lease right-of-use assets	3,897	4,230
Other non-current assets	897	115
TOTAL ASSETS	129,061	161,618
CURRENT LIABILITIES
Accounts payable	1,863	2,254
Operating lease liabilities	415	319
Deferred revenue	4,791
Accrued and other current liabilities	13,359	13,870
Total current liabilities	20,428	16,443
Non-current operating lease liabilities	4,746	5,129
Deferred revenue, net of current portion	1,614
Other non-current liabilities	192	214
TOTAL LIABILITIES	26,980	21,786
Commitments and Contingencies (Note 8)
STOCKHOLDERS’ EQUITY
Preferred stock, $0.0001 par value; 10,000,000 shares authorized as of September 30, 2021 and December 31, 2020; no shares issued and outstanding as of September 30, 2021 and December 31, 2020
Common stock, $0.0001 par value; 500,000,000 shares authorized as of September 30, 2021 and December 31, 2020; 49,306,107 shares and 47,959,086 shares issued and outstanding as of September 30, 2021 and December 31, 2020, respectively	5	5
Additional paid-in capital	423,437	415,824
Accumulated other comprehensive income	2	11
Accumulated deficit	(321,363)	(276,008)
TOTAL STOCKHOLDERS’ EQUITY	102,081	139,832
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 129,061	$ 161,618