Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 94,031	$ 110,890
Restricted cash	110	110
Prepaid expenses	3,472	4,031
Research and development rebate receivable	28	743
Other current assets	7	2,423
Total current assets	97,648	118,197
Investment in equity securities	1,710	4,700
Other assets	2,337	635
Total Assets	101,695	123,532
Current liabilities
Accounts payable	718	2,965
Accrued expenses	1,261	1,059
Payroll liabilities	1,444	1,525
Other current liabilities	21	19
Total current liabilities	3,444	5,568
Total Liabilities	3,444	5,568
Commitments and contingencies (Note 15)
Stockholders' equity
Series B convertible preferred stock - $0.001 par value; 10,000 shares authorized; 1 share issued and outstanding as of September 30, 2023 and December 31, 2022	0	0
Common stock - $0.18 par value; 175,000 shares authorized; 125,304 and 126,624 shares issued and outstanding as of September 30, 2023 and December 31, 2022, respectively	22,792	22,792
Additional paid-in capital - common stock	254,886	250,784
Treasury stock, at cost; 1,320 and 0 shares of common stock at September 30, 2023 and December 31, 2022, respectively	(1,475)	0
Accumulated deficit	(178,534)	(156,194)
Total Stockholders' Equity	98,251	117,964
Total Liabilities and Stockholders' Equity	101,695	123,532
Series B Preferred Stock [Member]
Stockholders' equity
Additional paid-in capital - Series B convertible preferred stock	$ 582	$ 582