Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Cash flows from operating activities:
Net loss	$ (10,214)	$ (10,852)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation	1,258	1,128
Depreciation and amortization	95	14
Loss on disposal of fixed assets	3	0
Accretion on marketable securities	(426)	900
Changes in operating assets and liabilities:
Prepaid and other current assets	(1,161)	(744)
Other assets	117	118
Accounts payable, accrued liabilities and other liabilities	(2,052)	(1,268)
Net cash used in operating activities	(12,380)	(10,704)
Cash flows from investing activities:
Purchase of marketable securities	(60,836)	(30,291)
Sale of marketable securities	64,400	60,070
Investment in Cend Therapeutics	0	(10,000)
Purchase of property and equipment	0	235
Net cash provided by investing activities	3,564	19,544
Cash flows from financing activities:
Proceeds from exercise of options	155	0
Tax withholding payments on net share settlement equity awards	(85)	(168)
Net proceeds from issuance of common stock	297	29
Net cash provided by (used in) financing activities	367	(139)
Effect of exchange rate changes on cash	(15)	0
Net (decrease) increase in cash and cash equivalents	(8,464)	8,701
Cash and cash equivalents at beginning of period	32,154	24,647
Cash and cash equivalents at end of period	$ 23,690	$ 33,348