Condensed Consolidated Balance Sheets - USD ($)	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Statement of Financial Position [Abstract]
Cash and cash equivalents	$ 45,754,000		$ 51,829,000
Insurance recovery of legal settlement	15,000,000		15,000,000
Prepaid expenses and other current assets	1,956,000	$ 2,134,000	2,134,000
Total current assets	62,710,000		68,963,000
Property and equipment — net	1,024,000	1,113,000	1,113,000
Operating lease right-of-use assets	2,739,000		3,051,000
Other noncurrent assets	480,000		111,000
Total assets	66,953,000		73,238,000
Accounts payable	684,000		991,000
Accrued legal settlement	15,000,000	15,000,000	15,000,000
Accrued expenses	3,234,000	1,589,000	1,589,000
Current operating lease liabilities	1,473,000		1,442,000
Accrued compensation	330,000		912,000
Interest payable	94,000		92,000
Total current liabilities	20,815,000		20,026,000
Loan payable (net of discount and issuance costs of $692 and $756, respectively)	15,133,000		15,069,000
Operating lease liabilities	1,648,000		2,026,000
Total liabilities	37,596,000		37,121,000
Commitments and contingencies (Note 6)
Common stock, $0.001 par value; 100,000,000 shares authorized at March 31, 2022 and December 31, 2021; 7,173,094 and 6,910,324 shares issued and outstanding at March 31, 2022 and December 31, 2021, respectively	7,000		7,000
Additional paid-in capital	137,904,000		136,173,000
Accumulated deficit	(108,554,000)		(100,063,000)
Total stockholders’ equity	29,357,000		36,117,000
Total liabilities and stockholders’ equity	$ 66,953,000		$ 73,238,000