Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating Activities
Net loss	$ (15,076)	$ (12,501)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and other expense	38	43
Share-based compensation	2,324	2,470
Changes in operating assets and liabilities:
Income tax receivable	(2,942)	0
Prepaid expense and other assets	(140)	(306)
Accrued research and development expenses	1,524	(1,427)
Accounts payable and accrued expenses	(3,254)	(2,882)
Net cash used in operating activities	(17,526)	(14,603)
Investing Activities
Net cash provided by (used in) investing activities	0	0
Financing Activities
Proceeds from employee stock plan purchases	179	41
Net cash provided by financing activities	179	41
Net change in cash and cash equivalents	(17,347)	(14,562)
Cash and cash equivalents
Beginning of period	125,699	131,201
End of period	$ 108,352	$ 116,639