Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 14,472	$ 10,264
Short-term investments	17,971	6,800
Restricted cash	5,333	19,468
Prepaid and other current assets	1,309	958
Accounts receivable	24	31
Total current assets	39,109	37,521
Restricted cash, noncurrent		125
Deposits, noncurrent	128
Property and equipment, net	276	444
Total assets	39,513	38,090
Current liabilities:
Accounts payable	747	837
Accrued compensation	1,366	596
Other accrued liabilities	1,322	805
Deferred revenue, current portion	212	283
Deferred rent, current portion	7	41
Redeemable convertible notes	5,085	19,403
Total current liabilities	8,739	21,965
Deferred revenue, noncurrent portion		47
Deferred rent, noncurrent portion		7
Total liabilities	8,739	22,019
Stockholders’ equity:
Preferred stock, $0.001 par value, 5,000,000 shares authorized; 3,680 and 0 shares issued and outstanding at December 31, 2017 and 2016, respectively
Common stock, $0.001 par value, 100,000,000 shares authorized; 6,081,230 and 801,756 shares issued and outstanding at December 31, 2017 and 2016, respectively	6	1
Additional paid-in capital	204,262	164,053
Accumulated other comprehensive income (loss)		(1)
Accumulated deficit	(173,494)	(147,982)
Total stockholders’ equity	30,774	16,071
Total liabilities and stockholders’ equity	$ 39,513	$ 38,090