BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 211,237	$ 22,860
Investments, short-term	31,322	126,605
Accounts receivable, net of allowance for credit losses of $34 and $48, respectively	10,235	13,131
Inventories	9,966	5,834
Prepaid expenses and other current assets	4,348	2,206
Total current assets	267,108	170,636
Investments, long-term	0	6,276
Property and equipment, net	3,307	3,045
Operating lease right-of-use asset	424	915
Other non-current assets	469	381
Total assets	271,308	181,253
Current liabilities:
Accounts payable	5,103	4,459
Accrued expenses	7,939	12,397
Total current liabilities	13,042	16,856
Notes payable	24,632	24,522
Other non-current liability	40	40
Total liabilities	37,714	41,418
Stockholders' equity:
Preferred Stock, $0.001 par value, 10,000,000 shares authorized; no shares issued and outstanding at June 30, 2020 and December 31, 2019	0	0
Common Stock, $0.001 par value per share; 200,000,000 shares authorized; 26,751,091 and 24,107,350 issued and outstanding at June 30, 2020 and December 31, 2019, respectively	27	24
Additional paid-in capital	452,891	319,865
Accumulated other comprehensive income	154	102
Accumulated deficit	(219,478)	(180,156)
Total stockholders' equity	233,594	139,835
Total liabilities and stockholders' equity	$ 271,308	$ 181,253