CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 43,836	$ 11,232
Marketable securities	150,586	53,151
Accounts and other receivables	1,802	1,015
Prepaid and other current assets	1,619	1,300
Total current assets	197,843	66,698
Property and equipment, net	3,815	4,031
Operating lease right-of-use assets, net	3,449	3,473
Intangible assets, net	30,690	48,690
Other assets	41	41
Total assets	235,838	122,933
Current liabilities:
Accounts payable	1,048	1,174
Accrued expenses	8,459	6,499
Current portion of operating lease liabilities	1,327	1,944
Current portion of long-term liabilities	3,372	2,026
Total current liabilities	14,206	11,643
Long-term portion of operating lease liabilities	2,154	1,713
Other long-term liabilities	10,121	15,551
Total liabilities	26,481	28,907
Commitments and contingent liabilities (Note 14)
Stockholders' equity:
Convertible preferred stock, $.01 par value; 3,000,000 shares authorized; no shares issued and outstanding at December 31, 2020 and 2019
Common stock, $.001 par value; 297,000,000 shares authorized; 39,603,771 and 16,972,077 shares issued and outstanding at December 31, 2020 and 2019, respectively	40	17
Additional paid-in capital	1,279,824	1,104,706
Accumulated other comprehensive income	2,589	2,619
Accumulated deficit	(1,073,096)	(1,013,316)
Total stockholders' equity	209,357	94,026
Total liabilities and stockholders' equity	$ 235,838	$ 122,933