Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net loss	$ (13,654)	$ (13,654)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	19	20
Stock-based compensation	804	806
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,918)	217
Accounts payable and accrued expenses	(489)	684
Net cash used in operating activities	(15,238)	(11,927)
Investing activities:
Purchase of short-term investments	(21,014)
Sale of short-term investments	12,502
Purchase of property and equipment		(13)
Net cash used in investing activities	(8,512)	(13)
Financing activities:
Proceeds from issuance of common stock, net of issuance costs		9,194
Net cash provided by financing activities		9,194
Decrease in cash and cash equivalents	(23,750)	(2,746)
Cash and cash equivalents at beginning of year	27,285	30,031
Cash and cash equivalents at end of year	$ 3,535	$ 27,285