Consolidated Balance Sheets - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 25,031,280	$ 55,061,329
Short-term investment securities	19,853,860	22,166,512
Interest receivable	83,852	186,021
Prepaid research and development	5,678,755	9,151,142
Other current assets	216,397	308,327
Total current assets	50,864,144	86,873,331
Restricted cash	583,208	579,143
Long-term investment securities	0	25,003,032
Leasehold interest, net	2,042,281	0
Equipment, net	328,148	47,122
Goodwill	799,391	799,391
Other assets	164,375	171,182
Total assets	54,781,547	113,473,201
Current liabilities:
Accounts payable and accrued expenses	15,267,668	9,346,068
Accrued compensation	1,389,516	818,472
Current portion of deferred revenue	152,381	152,381
Notes payable	68,875	211,549
Total current liabilities	16,878,440	10,528,470
Deferred rent	816,257	0
Deferred revenue, net of current portion	1,219,048	1,371,429
Total liabilities	18,913,745	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 December 31, 2016 and 2015)	0	0
Common stock, $0.001 par value per share (150,000,000 shares authorized, 56,820,423 and 54,095,110 shares issued, 56,779,114 and 54,053,801 shares outstanding at December 31, 2016 and 2015, respectively)	56,820	54,095
Contingently issuable shares	0	6
Additional paid-in capital	272,432,139	259,887,464
Treasury stock, at cost, 41,309 shares at December 31, 2016 and 2015	(234,337)	(234,337)
Accumulated deficit	236,386,820	158,133,926
Total stockholders’ equity	35,867,802	101,573,302
Total liabilities and stockholders’ equity	$ 54,781,547	$ 113,473,201