Unaudited Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating Activities
Net loss	$ (41,381,000)	$ (41,027,000)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and other expense	123,000	139,000
Gain on sale of property and equipment	(150,000)	0
Deferred income taxes	0	233,000
Share-based compensation	6,803,000	8,348,000
Changes in operating assets and liabilities:
Income tax receivable	1,635,000	1,387,000
Prepaid expense and other assets	979,000	1,096,000
Accrued research and development expenses	(2,387,000)	932,000
Accounts payable and accrued expenses	(2,203,000)	(2,937,000)
Net cash used in operating activities	(36,581,000)	(31,829,000)
Investing Activities
Proceeds from sale of assets	150,000	0
Net cash provided by (used in) investing activities	150,000	0
Financing Activities
Proceeds from employee stock plan purchases	81,000	65,000
Net cash provided by financing activities	81,000	65,000
Net change in cash and cash equivalents	(36,350,000)	(31,764,000)
Cash and cash equivalents
Beginning of period	131,201,000	166,972,000
End of period	94,851,000	135,208,000
Supplemental disclosure of cash paid
Income tax refunds received	$ 1,765,000	$ 2,467,000