CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 72,184	$ 43,836
Marketable securities	350,905	150,586
Accounts and other receivables	197	1,802
Prepaid and other current assets	3,269	1,619
Total current assets	426,555	197,843
Property and equipment, net	3,342	3,815
Operating lease right-of-use assets, net	3,016	3,449
Intangible assets, net	27,190	30,690
Other assets	98	41
Total assets	460,201	235,838
Current liabilities:
Accounts payable	836	1,048
Accrued expenses	10,253	8,459
Current portion of operating lease liabilities	1,366	1,327
Current portion of other long-term liabilities	1,721	3,372
Total current liabilities	14,176	14,206
Long-term portion of operating lease liabilities	1,713	2,154
Other long-term liabilities	7,600	10,121
Total liabilities	23,489	26,481
Commitments and contingent liabilities
Stockholders' equity:
Convertible preferred stock, $.01 par value; 3,000,000 shares authorized; no shares issued and outstanding at September 30, 2021 and December 31, 2020
Common stock, $.001 par value; 297,000,000 shares authorized; 46,663,340 and 39,603,771 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	47	40
Additional paid-in capital	1,557,576	1,279,824
Accumulated other comprehensive income	2,548	2,589
Accumulated deficit	(1,123,459)	(1,073,096)
Total stockholders' equity	436,712	209,357
Total liabilities and stockholders' equity	$ 460,201	$ 235,838