Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net loss	$ (9,378)	$ (3,942)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation of equipment	49	46
Amortization of intangible assets	333	332
Stock-based compensation	3,053	389
Net premium amortization on investments	14
Deferred rent/landlord incentive for tenant improvements	2,119
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(449)	(506)
Accounts payable	586	71
Accrued expenses	67	(141)
Other asset	(101)
Net cash used in operating activities	(3,707)	(3,751)
Cash flows from investing activities:
Purchases of property and equipment	(2,464)	(61)
Purchases of investments	(11,363)	(495)
Maturities of investments	12,249
Net cash used in investing activities	(1,578)	(556)
Cash flows from financing activities:
Proceeds from issuance of common stock	4,965	20,915
Proceeds from exercise of warrants	51
Proceeds from exercises of stock options	170
Net cash provided by financing activities	5,186	20,915
Net increase (decrease) in cash	(99)	16,608
Cash and cash equivalents at beginning of period	2,089	3,606
Cash and cash equivalents at end of period	$ 1,990	20,214
Supplemental disclosure of noncash investing and financing activities:
Reclassification of deferred offering costs to additional paid-in capital upon initial public offering		$ 560