Consolidated Balance Sheets-Unaudited - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 97,652	$ 126,263
Short-term investments	43,709	26,012
Accounts receivable, net	101	395
Prepaid expenses and other current assets	3,954	5,049
Total current assets	145,416	157,719
Property and equipment, net of accumulated depreciation and amortization of $5,851 and $5,815, respectively	296	295
Goodwill	44,543	44,543
Other assets	3,005	1,231
Total assets	193,260	203,788
Current liabilities:
Accounts payable	4,926	5,469
Accrued liabilities	22,409	29,691
Current portion of long-term debt, net of deferred issuance costs	11,660	11,646
Total current liabilities	38,995	46,806
Other long-term liabilities	1,718	611
Total liabilities	40,713	47,417
Commitments and contingencies
Equity:
Preferred stock, $0.01 par value; 5,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.001 par value; 225,000 shares authorized; 145,552 and 142,289 shares issued, respectively	145	142
Additional paid-in capital	1,580,891	1,561,096
Accumulated deficit	(1,420,976)	(1,400,018)
Accumulated other comprehensive loss	5	(6)
Treasury stock, at cost, 1,165 and 793 shares, respectively	(7,518)	(4,843)
Total stockholder's equity (deficit)	152,547	156,371
Total liabilities and equity	$ 193,260	$ 203,788