Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 23,179	$ 35,078
Short-term investments	0	999
Prepaid expenses and other current assets	4,184	3,748
Other receivables	181	210
Total current assets	27,544	40,035
Non-current assets:
Right-of-use asset	534	603
Total assets	28,078	40,638
Current liabilities:
Accounts payable	569	890
Accrued expenses	3,552	5,858
Current portion of lease liability	293	282
Total current liabilities	4,414	7,030
Long-term liabilities:
Royalty obligation payable to Iowa Economic Development Authority	6,000	6,000
Lease liability	225	303
Total liabilities	10,639	13,333
Commitments and contingencies
Stockholders' equity:
Undesignated preferred stock, $0.01 par value: Authorized shares - 5,000,000 at March 31, 2024 and December 31, 2023; issued and outstanding shares - 0 at March 31, 2024 and December 31, 2023	0	0
Common stock, $0.01 par value: Authorized shares - 75,000,000 at March 31, 2024 and December 31, 2023; issued shares - 8,132,007 and 8,125,728 at March 31, 2024 and December 31, 2023, respectively, and outstanding shares - 8,107,121 and 8,102,555 at March 31, 2024 and December 31, 2023, respectively	81	81
Treasury stock, at cost, 24,886 and 23,173 shares at March 31, 2024 and December 31, 2023, respectively	(201)	(196)
Additional paid-in capital	189,517	188,937
Accumulated deficit	171,958	161,517
Total stockholders' equity	17,439	27,305
Total liabilities and stockholders' equity	$ 28,078	$ 40,638