Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 11,863	$ 20,715
Investments	38,889	0
Prepaid expenses and other current assets	1,000	333
Restricted cash	88	25
Total current assets	51,840	21,073
Property and equipment, net	154	107
Restricted cash		63
Other assets	694	778
Total assets	52,688	22,021
Current liabilities:
Accounts payable	1,600	1,971
Accrued expenses and other current liabilities	3,291	2,100
Total current liabilities	4,891	4,071
Deferred rent		11
Total liabilities	4,891	4,082
Commitments and contingencies (Note 12)
Redeemable convertible preferred stock (Series A, A-1, B, C-1, C-2, D, D-1, E, E-1, E-2, E-3 and F), $0.01 par value; no shares and 151,557,293 shares authorized at December 31, 2017 and 2016, respectively; no shares and 105,631,019 shares issued and outstanding at December 31, 2017 and 2016, respectively	0	129,745
Stockholders’ equity (deficit):
Preferred stock, $0.001 par value; 5,000,000 shares and no shares authorized at December 31, 2017 and 2016, respectively; no shares issued and outstanding at December 31, 2017 and 2016
Common stock, $0.001 par value; 150,000,000 shares and 143,500,000 shares authorized at December 31, 2017 and 2016, respectively; 14,723,818 and 432,413 shares issued and outstanding at December 31, 2017 and 2016, respectively	15
Additional paid-in capital	184,761	2,536
Accumulated other comprehensive loss	(33)
Accumulated deficit	(136,946)	(114,342)
Total stockholders’ equity (deficit)	47,797	(111,806)
Total liabilities, redeemable convertible preferred stock and stockholders’ equity (deficit)	$ 52,688	$ 22,021