Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current Assets:
Cash and cash equivalents	$ 19,859	$ 15,872
Short-term Investments	51,358	56,904
Prepaid expenses and other current assets	6,175	5,153
Total current assets	77,392	77,929
Property and equipment, net	527	1,023
Acquired intangible asset	2,258	2,258
Goodwill	881	881
Right-of-use lease assets	296	530
Other assets	1,957	1,477
Total Assets	83,311	84,098
Current Liabilities:
Accounts payable	5,044	5,146
Accrued expenses	7,633	8,584
Lease liabilities	258	238
Total current liabilities	12,935	13,968
Royalty purchase liability	128,063	63,369
Lease liabilities, net of current portion	44	296
Deferred tax liability	273	273
Other liabilities	0	74
Total liabilities	141,315	77,980
Commitments (Note 8)
Stockholders’ Equity:
Preferred stock, $0.001 par value: 10,000,000 shares authorized; no shares issued and outstanding.	0	0
Common stock, $0.001 par value: 200,000,000 shares authorized; 26,458,767 and 24,976,142 shares issued and outstanding at December 31, 2021 and 2020, respectively	26	25
Additional paid-in capital	258,086	241,649
Accumulated other comprehensive income	(14)	12
Accumulated deficit	(316,102)	(235,568)
Total stockholders’ equity	(58,004)	6,118	$ 69,608
Total liabilities and stockholders' equity	$ 83,311	$ 84,098