Condensed Consolidated Balance Sheets - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 12,753,694	$ 11,444,055
Investment securities - available for sale, at fair value	13,442,107	12,724,020
Accrued interest receivable on investment securities	56,832	54,440
Advances, deposits and other current assets	89,186	89,186
Subtotal current assets	26,341,819	24,311,701
Property and equipment (at cost, less accumulated depreciation and amortization of $2,899,400 and $2,838,716, respectively)	192,785	175,771
Other assets:
In-process research and development	20,246,491	20,246,491
Other intangible assets, net	681,950	795,608
Goodwill	1,976,101	1,976,101
Patent licensing fees, deposits and other assets, net	70,761	8,761
Subtotal other assets	22,975,303	23,026,961
Total assets	49,509,907	47,514,433
Current liabilities:
Accounts payable - trade	3,703,073	3,416,863
Other accrued liabilities	2,032,393	2,282,827
Deferred revenue - current portion	500,000	500,000
Subtotal current liabilities	6,235,466	6,199,690
Earn-out milestone liability	13,085,849	12,538,525
Notes payable - non-current portion	9,222,121
Deferred revenue - non-current portion	1,750,000	2,000,000
Other liabilities - non-current portion	68,755	71,710
Total liabilities	30,362,191	20,809,925
Commitments and contingencies
Stockholders' equity:
Preferred Stock - $0.01 par value (100,000 shares authorized; no shares issued or outstanding at June 30, 2018 and December 31, 2017)
Common stock - $0.01 par value (112,500,000 shares authorized; 17,746,619 and 17,277,299 shares issued at June 30, 2018 and December 31, 2017, respectively, and 17,746,285 and 17,276,965 shares outstanding at June 30, 2018 and December 31, 2017, respectively)	177,466	172,772
Additional paid-in capital	293,549,124	288,408,976
Accumulated other comprehensive loss	(4,247)	(10,164)
Accumulated deficit	(274,489,439)	(261,781,888)
Subtotal	19,232,904	26,789,696
Treasury stock, at cost (334 shares at June 30, 2018 and December 31, 2017)	(85,188)	(85,188)
Total stockholders' equity	19,147,716	26,704,508
Total liabilities and stockholders' equity	$ 49,509,907	$ 47,514,433