Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Total revenue	$ 49,417	$ 35,936
Cost of sales	24,083	14,451
Gross profit	25,334	21,485
Operating expenses:
Research and development	23,637	25,437
General and administrative	12,551	11,516
Sales and marketing	6,467	4,740
Total operating expenses	42,655	41,693
Loss from operations	(17,321)	(20,208)
Interest expense	(890)	(764)
Other income, net	457	118
Loss on extinguishment of debt		(246)
Net loss and comprehensive loss	$ (17,754)	$ (21,100)
Net loss per common share, basic and diluted	$ (1.08)	$ (1.69)
Weighted-average shares used to compute net loss per common share, basic and diluted	16,372,638	12,484,984
Product sales
Total revenue	$ 39,514	$ 30,838
Licensing, royalty and other revenue
Total revenue	$ 9,903	$ 5,098