Condensed Consolidated Balance Sheets - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 60,300,086	$ 55,713,784
Short-term investment securities	31,765,910	23,062,034
Interest receivable	190,313	85,516
Prepaid research and development	10,921,958	6,179,743
Other current assets	548,776	173,952
Total current assets	103,727,043	85,215,029
Restricted cash	577,110	575,012
Long-term investment securities	18,311,340	0
Equipment, net	34,833	20,357
Goodwill	799,391	799,391
Other assets	155,564	137,101
Total assets	123,605,281	86,746,890
Current liabilities:
Accounts payable and accrued expenses	8,254,189	3,991,625
Accrued compensation	506,000	702,000
Current portion of deferred revenue	152,381	152,381
Notes payable	295,360	275,190
Total current liabilities	9,207,930	5,121,196
Deferred revenue, net of current portion	1,447,619	1,523,810
Total liabilities	$ 10,655,549	$ 6,645,006
Commitments and contingencies
Equity:
Preferred stock, $0.001 par value per share (10,000,000 shares authorized, none issued and outstanding as of June 30, 2015 and December 31, 2014)	$ 0	$ 0
Common stock, $0.001 par value per share (150,000,000 shares authorized, 51,697,864 and 44,974,248 shares issued, 51,656,555 and 44,932,939 shares outstanding at June 30, 2015 and December 31, 2014, respectively)	51,698	44,974
Contingently issuable shares	6	6
Additional paid-in capital	239,998,563	175,476,521
Treasury stock, at cost	(234,337)	(234,337)
Accumulated deficit	(126,866,198)	(95,185,280)
Total equity	112,949,732	80,101,884
Total liabilities and equity	$ 123,605,281	$ 86,746,890