Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 46,261	$ 15,861
Short-term marketable securities	0	61,768
Prepaid expenses and other current assets	3,296	2,153
Total current assets	49,557	79,782
Property and equipment, net	6,398	7,323
Right of use asset - operating lease	13,662	14,356
Restricted cash	1,097	1,097
Prepaid research and development, net of current portion	8,554	8,300
Other assets	16	7
Total assets	79,284	110,865
Current liabilities:
Accounts payable	1,082	1,785
Accrued expenses	3,543	5,290
Deferred revenue	657	882
Lease liability - operating lease	4,339	4,152
Finance lease obligations	11	13
Total current liabilities	9,632	12,122
Long-term liabilities:
Lease liability - operating lease, net of current portion	14,878	16,129
Finance lease obligations, net of current portion	0	4
Total long-term liabilities	14,878	16,133
Commitments and contingencies (Note 12)
Stockholders' equity
Common stock, $0.001 par value 250,000,000 shares authorized as of June 30, 2023 and December 31, 2022. 72,810,751 shares issued and 68,613,862 shares outstanding as of June 30, 2023 and 70,933,140 shares issued and 66,736,251 shares outstanding as of December 31, 2022.	73	71
Additional paid-in capital	444,906	442,237
Accumulated other comprehensive income (loss)	2	(161)
Accumulated deficit	(387,689)	(357,019)
Treasury stock, at cost (4,196,889 shares at June 30, 2023 and December 31, 2022)	(2,518)	(2,518)
Total stockholders' equity	54,774	82,610
Total liabilities and stockholders' equity	$ 79,284	$ 110,865