Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 334,718	$ 389,705
Accounts receivable	80	92
Prepaid expenses and other current assets	3,616	20,690
Short-term investments	144,829	201,881
Total current assets	483,243	612,368
Property and equipment, net	1,350	1,171
Operating lease right-of-use assets	4,833	5,055
Intangible assets, net	308	332
Other assets	193	193
Long-term investments	152,481	35,970
Total assets	642,408	655,089
Current liabilities:
Accounts payable	2,022	1,890
Current portion of operating lease liabilities	790	734
Accrued expenses and other current liabilities	5,073	6,313
Total current liabilities	7,885	8,937
Operating lease liabilities, net of current portion	4,838	5,076
Debt, net of current portion	0	908
Total liabilities	12,723	14,921
Stockholders’ Equity:
Common stock, $0.0001 par value; 250,000,000 shares authorized; 171,519,811 and 169,316,421 shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively	19	19
Additional paid-in capital	371,077	364,998
Accumulated deficit	258,589	275,151
Total stockholders’ equity	629,685	640,168
Total liabilities and stockholders’ equity	$ 642,408	$ 655,089