Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 123,404	$ 143,745
Short-term investments	24,254	22,742
Accounts receivable	81	71
Prepaid expenses and other current assets	6,441	2,609
Total current assets	154,180	169,167
Long-term investments	9,349	16,210
Property and equipment, net	7,629	6,601
Right-of-use assets, net	12,870	13,168
Intangible assets, net	10,286	10,624
Goodwill	4,508	4,508
Other long-term assets	1,556	890
Total assets	200,378	221,168
Current liabilities:
Accounts payable	4,017	3,872
Current portion of operating lease liability	1,079	1,011
Current portion of liability related to sale of future royalties	836	836
Other accrued liabilities	5,103	5,064
Total current liabilities	11,035	10,783
Operating lease liability, net of current portion	11,837	11,997
Liability related to sale of future royalties, net of current portion	10,955	10,686
Other long-term liabilities	186	171
Total liabilities	34,013	33,637
Commitments and contingencies (Note 8)
Stockholders’ equity:
Preferred stock: $0.0001 par value; 5,000,000 shares authorized; none issued and outstanding as of March 31, 2022 and December 31, 2021	0	0
Common stock: $0.0001 par value; 150,000,000 shares authorized; 125,840,811 and 125,594,393 shares issued and outstanding as of March 31, 2022 and December 31, 2021, respectively	13	13
Additional paid-in capital	411,113	406,943
Accumulated deficit	(244,452)	(219,351)
Accumulated other comprehensive loss	(309)	(74)
Total stockholders’ equity	166,365	187,531
Total liabilities and stockholders’ equity	$ 200,378	$ 221,168