Condensed Consolidated Balance Sheets - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 36,478,420	$ 55,061,329
Short-term investment securities	22,224,258	22,166,512
Interest receivable	164,106	186,021
Prepaid research and development	10,979,437	9,151,142
Other current assets	730,523	308,327
Total current assets	70,576,744	86,873,331
Restricted cash	580,151	579,143
Long-term investment securities	26,458,226	25,003,032
Prepaid rent	1,151,163	0
Property, plant and equipment, net	323,003	47,122
Goodwill	799,391	799,391
Other assets	173,841	171,182
Total assets	100,062,519	113,473,201
Current liabilities:
Accounts payable and accrued expenses	8,139,440	9,346,068
Accrued compensation	449,126	818,472
Current portion of deferred revenue	152,381	152,381
Notes payable	152,917	211,549
Total current liabilities	8,893,864	10,528,470
Deferred rent	389,554	0
Deferred revenue, net of current portion	1,333,333	1,371,429
Total liabilities	$ 10,616,751	$ 11,899,899
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value per share (10,000,000 shares authorized, none issued and outstanding as of March 31, 2016 and December 31, 2015)	$ 0	$ 0
Common stock, $0.001 par value per share (150,000,000 shares authorized, 54,118,722 and 54,095,110 shares issued, 54,077,413 and 54,053,801 shares outstanding at March 31, 2016 and December 31, 2015, respectively)	54,119	54,095
Contingently issuable shares	6	6
Additional paid-in capital	261,608,568	259,887,464
Treasury stock, at cost, 41,309 shares at March 31, 2016 and December 31, 2015	(234,337)	(234,337)
Accumulated deficit	(171,982,588)	(158,133,926)
Total stockholders’ equity	89,445,768	101,573,302
Total liabilities and stockholders’ equity	$ 100,062,519	$ 113,473,201