BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 18,574	$ 37,172
Short-term investments	289,424	203,906
Prepaid expenses and other current assets	4,744	3,269
Total current assets	312,742	244,347
Long-term investments	46,980	2,287
Property and equipment, net	2,728	1,215
Operating lease right-of-use assets	9,376
Total assets	371,826	247,849
Current liabilities:
Accounts payable	5,911	8,460
Current operating lease liabilities	1,072
Accrued expenses and other current liabilities	32,780	6,344
Total current liabilities	39,763	14,804
Liabilities, Noncurrent [Abstract]
Term Loan	58,374	38,071
Non-current operating lease liabilities	8,783
Other long-term liabilities	1,023	449
Total liabilities	107,943	53,324
Commitments and contingencies (Note 7)
Convertible preferred stock	0	0
Stockholders’ equity:
Preferred stock	0	0
Common stock	50	42
Additional paid-in capital	632,647	386,830
Accumulated other comprehensive income (loss)	193	(153)
Accumulated deficit	(369,007)	(192,194)
Total stockholders’ equity	263,883	194,525
Total liabilities and stockholders’ equity	$ 371,826	$ 247,849