Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Product sales	$ 31,361	$ 24,233	$ 22,403
Licensing and royalty revenue	634	483	671
Total revenue	35,936	27,094	26,546
Cost of sales	14,451	12,395	12,568
Gross profit	21,485	14,699	13,978
Operating expenses:
Research and development	25,437	19,233	21,126
General and administrative	11,516	7,281	6,565
Sales and marketing	4,740	3,706	3,823
Total operating expenses	41,693	30,220	31,514
Loss from operations	(20,208)	(15,521)	(17,536)
Interest expense	(764)	(2,347)	(653)
Other income, net	118	1,160	6
Loss on extinguishment of debt	(246)
Net loss and comprehensive loss	$ (21,100)	$ (16,708)	$ (18,183)
Net loss per common share, basic and diluted	$ (1.69)	$ (3.53)	$ (7.12)
Weighted-average shares used to compute net loss per common share, basic and diluted	12,484,984	4,738,496	2,552,205
Related Party
Product sales	$ 2,316	$ 2,378	$ 3,472
Licensing and royalty revenue	$ 1,625