BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and Cash Equivalents, at Carrying Value	$ 101,945	$ 97,288
Short-term investments	75,069	90,922
Accounts receivable, net	7,036	6,667
Inventories	3,106	2,667
Prepaid expenses and other current assets	1,387	1,734
Total current assets	188,543	199,278
Property and equipment, net	974	802
Other non-current asset	89	0
Total assets	189,606	200,080
Current liabilities:
Accounts payable	3,203	3,429
Accrued expenses	4,623	7,726
Total current liabilities	7,826	11,155
Notes payable	24,364	24,926
Total liabilities	32,190	36,081
Stockholders' equity:
Common Stock, $0.001 par value per share; 200,000,000 shares authorized at March 31, 2019 and December 31, 2018; 23,503,010 and 23,401,675 issued and outstanding at March 31, 2019 and December 31, 2018, respectively	24	23
Additional paid-in capital	312,555	310,941
Accumulated other comprehensive income (loss)	16	(52)
Accumulated deficit	(155,179)	(146,913)
Total stockholders' equity	157,416	163,999
Total liabilities and stockholders' equity	$ 189,606	$ 200,080