BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 80,667	$ 26,586
Short-term investments	28,347	33,574
Prepaid expenses and other current assets	2,030	3,082
Total current assets	111,044	63,242
Long-term investments		26,997
Property and equipment, net	1,853	1,692
Restricted cash and other assets	334	345
Total assets	113,231	92,276
Current liabilities:
Accounts payable	556	1,169
Accrued expenses	7,394	4,274
Current portion of note payable	292	261
Current portion of deferred revenue	1,111	1,111
Total current liabilities	9,353	6,815
Deferred revenue, net of current portion	152	1,262
Note payable, net of current portion	209	501
Other liabilities	168	116
Total liabilities	9,882	8,694
Commitments and contingencies
Stockholders' equity:
Common stock, $0.001 par value, Authorized — 280,000 shares; Issued and outstanding — 149,065 and 121,265 shares at December 31, 2016 and December 31, 2015, respectively	149	121
Additional paid-in capital	641,687	583,676
Accumulated deficit	(538,470)	(500,081)
Accumulated other comprehensive loss	(17)	(134)
Total stockholders' equity	103,349	83,582
Total liabilities and stockholders' equity	113,231	92,276
Series A Preferred Stock
Stockholders' equity:
Preferred stock, $0.01 par value, Authorized — 5,000 shares: Series A convertible preferred stock; Designated — 1,500 shares, Issued and outstanding — 1 share