Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 342,453	$ 486,055
Marketable securities	63,466	26,573
Restricted cash	566	565
Prepaid expenses and other current assets	10,502	9,129
Total current assets	416,987	522,322
Property and equipment, net	5,632	5,534
Operating lease right-of-use assets	8,821	10,550
Other assets	1,070	1,027
Total assets	432,510	539,433
Current liabilities
Accounts payable	895	7,508
Accrued research and development expenses	13,206	10,431
Accrued expenses and other current liabilities	15,881	20,711
Total current liabilities	29,982	38,650
Long-term convertible senior notes	146,765	143,642
Long-term debt	28,905	28,744
Operating lease liabilities - long-term	6,165	7,713
Total liabilities	211,817	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 June 30, 2021 and December 31, 2020	0	0
Common stock, $0.0001 par value; 700,000,000 shares authorized as of June 30, 2021 and December 31, 2020; 75,988,241 shares issued and 74,834,952 shares outstanding as of June 30, 2021, and 75,524,254 shares issued and 73,874,904 shares outstanding as of December 31, 2020	8	8
Additional paid-in capital	915,414	897,607
Accumulated deficit	(695,003)	(577,530)
Accumulated other comprehensive income	274	599
Total stockholders' equity	220,693	320,684
Total liabilities and stockholders' equity	$ 432,510	$ 539,433