Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 16,168	$ 24,991
Marketable securities	50,019	62,263
Prepaid expenses and other current assets	843	432
Total current assets	67,030	87,686
Property and equipment and other assets, net	312	223
Total assets	67,342	87,909
Current liabilities:
Accounts payable	1,012	994
Accrued direct program expenses	2,837	1,555
Accrued employee benefits	1,345	1,675
Accrued other liabilities	44	195
Total current liabilities	5,238	4,419
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized and no shares issued and outstanding for both periods presented
Common stock, $0.001 par value; 200,000,000 shares authorized for both periods presented; 15,505,334 and 15,462,030 shares issued and outstanding, respectively	16	15
Additional paid-in capital	234,670	232,309
Accumulated other comprehensive income	5	3
Accumulated deficit	(172,587)	(148,837)
Total stockholders' equity	62,104	83,490
Total liabilities and stockholders' equity	$ 67,342	$ 87,909