CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 37,690	$ 27,742
Available-for-sale securities	118,077	26,568
Accounts receivable from related party	1,719	1,237
Prepaid expenses and other current assets	3,815	2,281
Total current assets	161,301	57,828
Available-for-sale securities, long-term	28,833
Property and equipment, net	5,633	6,337
Other assets	1,128	3,120
Total assets	196,895	67,285
Current liabilities:
Accounts payable	2,141	2,131
Accrued expenses and other current liabilities	5,573	5,665
Deferred collaboration liability, current	8,271	10,968
Deferred rent and lease incentive obligation, current	652	610
Total current liabilities	16,637	19,374
Long-term liabilities:
Deferred collaboration liability, long term	5,926	4,177
Deferred rent and lease incentive obligation, long term	4,571	4,901
Other long-term liabilities	350	523
Total liabilities	27,484	28,975
Commitments and contingencies (Note 6)
Convertible preferred stock		93,091
Stockholders’ (deficit) equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized, no shares issued and outstanding at June 30, 2021; no shares authorized, issued and outstanding at December 31, 2020
Common stock, $0.001 par value; 200,000,000 shares authorized, 24,901,931 shares issued and 24,868,817 outstanding at June 30, 2021; 115,000,000 shares authorized, 573,793 shares issued and 521,052 shares outstanding at December 31, 2020	25	1
Additional paid-in capital	354,591	107,908
Accumulated other comprehensive gain (loss)	5	(1)
Accumulated deficit	(185,210)	(162,689)
Total stockholders’ equity (deficit)	169,411	(54,781)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 196,895	67,285
Series A convertible preferred stock
Long-term liabilities:
Convertible preferred stock		16,176
Series B convertible preferred stock
Long-term liabilities:
Convertible preferred stock		5,700
Series C convertible preferred stock
Long-term liabilities:
Convertible preferred stock		16,759
Series D convertible preferred stock
Long-term liabilities:
Convertible preferred stock		$ 54,456