CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net loss	$ (23,599)	$ (10,609)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	359	330
Equity-based compensation	1,571	488
Amortization of deferred rent	(15)	(103)
Deferred payroll tax credit	190
Other	82	35
Change in operating assets and liabilities:
Prepaid expenses and other current assets	(753)	(456)
Accounts payable	464	638
Accrued expenses	191	(257)
Net cash used in operating activities	(21,510)	(9,934)
Cash flows from investing activities:
Purchase of property and equipment	(192)	(209)
Sales and maturities of marketable securities	1,498	3,001
Net cash provided by investing activities	1,306	2,792
Cash flows from financing activities:
Principal payments on loan payable	(333)	(333)
Proceeds from initial public offering of common stock, net of issuance costs	79,137
Proceeds from issuance of Series B convertible preferred units		4,285
Net cash provided by financing activities	78,804	3,952
Net increase (decrease) in cash and cash equivalents and restricted cash	58,600	(3,190)
Cash and cash equivalents and restricted cash, beginning of period	56,666	10,238
Cash and cash equivalents and restricted cash, end of period	115,266	7,048
Supplemental disclosure of non‑cash items:
Offering costs in accounts payable and accrued liabilities	1,302
Supplemental cash flow information:
Cash paid for interest	$ 19	$ 28