Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
CURRENT ASSETS
Cash and cash equivalents	$ 34,765	$ 90,095
Marketable securities	93,813	56,178
Prepaid expenses and other current assets	5,790	3,516
Total current assets	134,368	149,789
Restricted cash	1,846	1,842
Property and equipment, net	5,208	5,642
Operating lease right-of-use assets	4,012	4,230
Other non-current assets	1,548	115
TOTAL ASSETS	146,982	161,618
CURRENT LIABILITIES
Accounts payable	2,221	2,254
Operating lease liabilities	412	319
Deferred revenue	5,530
Accrued and other current liabilities	12,441	13,870
Total current liabilities	20,604	16,443
Non-current operating lease liabilities	4,880	5,129
Deferred revenue, net of current portion	2,274
Other non-current liabilities	200	214
TOTAL LIABILITIES	27,958	21,786
Commitments and Contingencies (Note 8)
STOCKHOLDERS’ EQUITY
Preferred stock, $0.0001 par value; 10,000,000 shares authorized as of June 30, 2021 and December 31, 2020; no shares issued and outstanding as of June 30, 2021 and December 31, 2020
Common stock, $0.0001 par value; 500,000,000 shares authorized as of June 30, 2021 and December 31, 2020; 49,025,956 shares and 47,959,086 shares issued and outstanding as of June 30, 2021 and December 31, 2020, respectively	5	5
Additional paid-in capital	420,064	415,824
Accumulated other comprehensive income	11	11
Accumulated deficit	(301,056)	(276,008)
TOTAL STOCKHOLDERS’ EQUITY	119,024	139,832
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 146,982	$ 161,618