Consolidated Statements of Operations and Comprehensive Loss - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Royalties	$ 258,062	$ 274,648	$ 270,178
License fees	0		10,000
Diagnostic services	86,137	13,789	0
Clinical research services	36,873	24,375	0
Total revenues	381,072	312,812	280,178
Costs and expenses:
Cost of revenue	1,730,512	629,191	15,441
Research and development	15,006,642	10,593,869	6,664,906
Selling and marketing	11,523,144	6,443,578	2,734,903
General and administrative	11,475,947	7,919,826	5,810,087
Restructuring charges	790,438	0	0
Total operating expenses	40,526,683	25,586,464	15,225,337
Loss from operations	(40,145,611)	(25,273,652)	(14,945,159)
Net interest expense	(1,375,512)	(1,468,221)	(831,020)
Other income (loss), net	(144,733)	(2,800)	24,845
Gain (loss) from change in fair value of derivative financial instruments—warrants	2,462,137	(726,421)	1,425,850
Net loss	(39,203,719)	(27,471,094)	(14,325,484)
Preferred stock dividend	(24,240)	(24,240)	(23,015)
Net loss attributable to common stockholders	$ (39,227,959)	$ (27,495,334)	$ (14,348,499)
Net loss per common share - basic (in dollars per share)	$ (1.30)	$ (1.05)	$ (0.76)
Net loss per common share - diluted (in dollars per share)	$ (1.37)	$ (1.21)	$ (0.88)
Weighted-average shares outstanding - basic (in shares)	30,174,838	26,201,713	18,904,280
Weighted-average shares outstanding - diluted (in shares)	30,281,263	26,452,165	19,071,112