Condensed Balance Sheets (Unaudited) - USD ($)
Mar. 31, 2018
Dec. 31, 2017
Current assets:    
Cash and cash equivalents $ 62,754,000 $ 7,298,000
Contribution receivable   1,382,000
Short-term marketable securities 71,281,000 79,212,000
Deferred offering costs 1,707,000 0
Prepaid expenses and other current assets 697,000 988,000
Total current assets 136,439,000 88,880,000
Property and equipment, net 6,591,000 6,958,000
Long-term marketable securities   5,118,000
Restricted cash 550,000 550,000
Other long-term assets 522,000 518,000
Total assets 144,102,000 102,024,000
Current liabilities:    
Accounts payable 5,037,000 2,378,000
Accrued compensation 958,000 2,181,000
Accrued and other current liabilities 4,668,000 3,338,000
Total current liabilities 10,663,000 7,897,000
Deferred rent, net of current portion 3,062,000 3,166,000
Other non-current liabilities 101,000 118,000
Total liabilities 13,826,000 11,181,000
Commitments and contingencies (Note 6)
Convertible preferred stock, $0.0001 par value; 103,283,818 and 91,739,149 shares authorized as of March 31, 2018 and December 31, 2017, respectively; 31,750,297 and 28,159,724 shares issued and outstanding as of March 31, 2018 and December 31, 2017, respectively; aggregate liquidation preference of $245,825 as of March 31, 2018 and $190,825 as of December 31, 2017, respectively 228,907,000 173,956,000
Stockholders’ deficit:    
Common stock, $0.0001 par value; 140,000,000 and 122,000,000 shares authorized as of March 31, 2018 and December 31, 2017, respectively; 5,230,976 and 4,830,389 shares issued and outstanding as of March 31, 2018 and December 31, 2017, respectively 1,000 1,000
Additional paid-in capital 5,511,000 4,072,000
Related party promissory notes for purchase of common stock (592,000) (202,000)
Employee promissory notes for purchase of common stock (400,000)  
Accumulated other comprehensive loss (138,000) (104,000)
Accumulated deficit (103,013,000) (86,880,000)
Total stockholders’ deficit (98,631,000) (83,113,000)
Total liabilities, convertible preferred stock, and stockholders’ deficit $ 144,102,000 $ 102,024,000