Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 11,439	$ 11,469
Short-term investments	32,718	32,424
Prepaid expenses and other current assets	7,251	1,067
Restricted cash	55	0
Total current assets	51,463	44,960
Other assets	812	572
Deferred offering costs	106	314
Restricted cash	273	0
Property and equipment	516	4
Total assets	53,170	45,850
Current liabilities:
Accounts payable	3,653	3,833
Accrued expenses	2,103	1,705
Deferred revenue, current portion	121	257
Loan payable, current portion	0	4,349
Total current liabilities	5,877	10,144
Deferred revenue, non-current	0	121
Warrant liabilities	986	3,872
Loan payable expected to be refinanced (see Note 7)	15,082	10,303
Total liabilities	21,945	24,440
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value, authorized 5,000,000 shares as of December 31, 2018 and December 31, 2017; 0 shares issued and outstanding as of December 31, 2018 and December 31, 2017	0	0
Common stock, $0.001 par value, authorized 125,000,000 shares as of December 31, 2018 and December 31, 2017; 47,971,989 and 28,971,651 shares issued and outstanding as of December 31, 2018, and December 31, 2017, respectively	48	29
Additional paid-in capital	248,895	226,631
Accumulated deficit	(217,718)	(205,250)
Total stockholders’ equity	31,225	21,410
Total liabilities and stockholders’ equity	$ 53,170	$ 45,850