Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net loss	$ (10,450)	$ (6,655)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	48	41
Non-cash stock-based compensation	276	649
Acquired in-process research and development	3,075
Value of non-marketable equity securities recognized as revenue		(9)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(121)	(10)
Accounts payable	(417)	(706)
Accrued expenses	276	302
Net cash used in operating activities	(7,313)	(6,388)
Cash flows from investing activities:
Purchase of short-term investments		(2,000)
Maturities of short-term investments		5,500
Cash acquired in MirImmune Inc. acquisition	100
Cash paid for purchase of property and equipment	(203)	(2)
Net cash (used in) provided by investing activities	(103)	3,498
Cash flows from financing activities:
Proceeds from the issuance of common stock, net of offering costs	(74)	152
Net cash (used in) provided by financing activities	(74)	152
Net decrease in cash, cash equivalents and restricted cash	(7,490)	(2,738)
Cash, cash equivalents and restricted cash at the beginning of period	12,956	5,167
Cash, cash equivalents and restricted cash at the end of period	5,466	$ 2,429
Supplemental disclosure of non-cash investing and financing activities:
Cancellation of notes receivable	150
Accounts payable assumed	5
Fair value of securities issued	2,824
Series B Convertible Preferred Stock [Member]
Supplemental disclosure of non-cash investing and financing activities:
Conversions of convertible preferred stock into common stock	3,525
Series C Convertible Preferred Stock [Member]
Supplemental disclosure of non-cash investing and financing activities:
Conversions of convertible preferred stock into common stock	$ 816