Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 439,659	$ 486,055
Marketable securities	13,638	26,573
Restricted cash	565	565
Prepaid expenses and other current assets	11,985	9,129
Total current assets	465,847	522,322
Property and equipment, net	5,920	5,534
Operating lease right-of-use assets	9,692	10,550
Other assets	1,010	1,027
Total assets	482,469	539,433
Current liabilities
Accounts payable	1,073	7,508
Accrued research and development expenses	11,509	10,431
Accrued expenses and other current liabilities	16,862	20,711
Total current liabilities	29,444	38,650
Long-term convertible senior notes	145,168	143,642
Long-term debt	28,823	28,744
Operating lease liabilities - long-term	6,950	7,713
Total liabilities	210,385	218,749
Commitments and contingencies
Stockholders' equity
Preferred stock, $0.0001 par value; 70,000,000 shares authorized; no shares issued or outstanding as of March 31, 2021 and December 31, 2020	0	0
Common stock, $0.0001 par value; 700,000,000 shares authorized as of March 31, 2021 and December 31, 2020; 75,903,538 shares issued and 74,493,150 shares outstanding as of March 31, 2021, and 75,524,254 shares issued and 73,874,904 shares outstanding as of December 31, 2020	8	8
Additional paid-in capital	907,089	897,607
Accumulated deficit	(635,171)	(577,530)
Accumulated other comprehensive income	158	599
Total stockholders' equity	272,084	320,684
Total liabilities and stockholders' equity	$ 482,469	$ 539,433