CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 79,694	$ 80,667
Short-term investments	11,568	28,347
Prepaid expenses and other current assets	4,235	2,030
Total current assets	95,497	111,044
Property and equipment, net	1,744	1,853
Restricted cash and other assets	332	334
Total assets	97,573	113,231
Current liabilities:
Accounts payable	1,353	556
Accrued expenses	4,369	7,394
Current portion of note payable	300	292
Current portion of deferred revenue	985	1,111
Total current liabilities	7,007	9,353
Deferred revenue, net of current portion		152
Note payable, net of current portion	131	209
Other liabilities	244	168
Total liabilities	7,382	9,882
Commitments and contingencies
Stockholders' equity:
Common stock, $0.001 par value, Authorized — 280,000 shares; Issued and outstanding — 149,135 and 149,065 shares at March 31, 2017 and December 31, 2016, respectively	149	149
Additional paid-in capital	643,611	641,687
Accumulated deficit	(553,568)	(538,470)
Accumulated other comprehensive loss	(1)	(17)
Total stockholders' equity	90,191	103,349
Total liabilities and stockholders' equity	97,573	113,231
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