Consolidated Balance Sheets-Unaudited - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 89,887,000	$ 126,263,000
Short-term investments	28,614,000	26,012,000
Accounts receivable, net	159,000	395,000
Prepaid expenses and other current assets	4,598,000	5,049,000
Total current assets	123,258,000	157,719,000
Property and equipment, net of accumulated depreciation and amortization of $4,746 and $5,815, respectively	1,201,000	295,000
Goodwill	44,543,000	44,543,000
Other assets	2,670,000	1,231,000
Total assets	171,672,000	203,788,000
Current liabilities:
Accounts payable	8,545,000	5,469,000
Accrued liabilities	12,595,000	29,691,000
Current portion of long-term debt, net of deferred issuance costs	11,675,000	11,646,000
Total current liabilities	32,815,000	46,806,000
Other long-term liabilities	1,624,000	611,000
Total liabilities	34,439,000	47,417,000
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; 145,640 and 142,289 shares issued, respectively	146,000	142,000
Additional paid-in capital	1,583,653,000	1,561,096,000
Accumulated deficit	(1,439,043,000)	(1,400,018,000)
Accumulated other comprehensive loss	(5,000)	(6,000)
Treasury stock, at cost, 1,165 and 793 shares, respectively	(7,518,000)	(4,843,000)
Total stockholder's equity (deficit)	137,233,000	156,371,000
Total liabilities and equity	$ 171,672,000	$ 203,788,000