Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 23,768	$ 24,614
Accounts receivable	1,956	4,489
Prepaid and other current assets	522	267
Total current assets	26,246	29,370
Other assets
Patents and patent applications - net of accumulated amortization	15	16
Total assets	26,261	29,386
Current liabilities
Accounts payable and accrued expenses	1,482	1,133
License fees	6,300	5,400
Accrued salaries and wages	618	1,084
Royalty payable	314	998
Deferred revenue	757	1,212
Total current liabilities	9,471	9,827
Long-term liabilities
License fees	0	2,700
Total long-term liabilities	0	2,700
Total liabilities	9,471	12,527
Stockholders' equity
Common stock; par value $0.001; 200,000,000 shares authorized; 3,925,361 and 3,845,361 shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively	4	4
Additional paid-in capital	92,943	91,276
Accumulated deficit	(76,157)	(74,421)
Total stockholders' equity	16,790	16,859
Total liabilities and stockholders' equity	$ 26,261	$ 29,386