Consolidated Balance Sheets - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 14,322,000	$ 21,464,000
Restricted cash	361,000	361,000
Marketable securities	7,525,000	11,577,000
Prepaid expenses and other current assets	657,000	451,000
Total current assets	22,865,000	33,853,000
Property, equipment and leasehold improvements, net	305,000	510,000
Other assets	409,000	421,000
Total assets	23,579,000	34,784,000
Current liabilities:
Accounts payable	878,000	1,011,000
Loan payable, current portion	437,000	423,000
Derivative warrant liability	519,000	1,314,000
Deferred rent, current portion	154,000	141,000
Accrued expenses	1,893,000	1,959,000
Total current liabilities	3,881,000	4,848,000
Loan payable, net of current portion	630,000	852,000
Deferred rent, net of current portion	54,000	135,000
Other liabilities	45,000
Total liabilities	4,610,000	5,835,000
Commitments and contingencies (Note 6)
Stockholders' equity:
Common stock, $0.00001 par value, authorized 100,000,000 shares; 32,175,179 shares issued and outstanding at June 30, 2017; 32,044,087 shares issued and outstanding at December 31, 2016	1,000	1,000
Accumulated other comprehensive loss	(1,000)
Additional paid-in capital	188,862,000	185,955,000
Accumulated deficit	(169,893,000)	(157,007,000)
Total stockholders' equity	18,969,000	28,949,000
Total liabilities and stockholders' equity	$ 23,579,000	$ 34,784,000