Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating Activities:
Net loss	$ (31,110)	$ (6,199)
Adjustments to reconcile net loss to net cash used in operating activities:
Accretion of discount on convertible notes	1,454	0
(Increase in) / reduction of lease liability	(109)	2
Depreciation expense	157	81
Share-based compensation expense	8,168	261
Loss on disposal of property and equipment	205	0
Accretion of discount on investments	(118)	0
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(651)	(436)
Accounts payable and accrued expenses	1,263	(32)
Accrued research and development costs	(598)	444
Net cash used in operating activities	(21,339)	(5,879)
Investing activities:
Cash acquired in connection with the Reverse Merger	76,348	0
Purchases of investments	(118,819)	0
Proceeds from maturities of investments	21,232	0
Proceeds from sale of property and equipment	20	0
Purchases of property and equipment	(117)	(729)
Net cash used in investing activities	(21,336)	(729)
Financing activities:
Proceeds from issuance of common stock, net of issuance costs	78,518	0
Proceeds from issuance of convertible preferred stock, net	0	25,445
Net cash provided by financing activities	78,518	25,445
Net change in cash, cash equivalents and restricted cash	35,843	18,837
Cash, cash equivalents and restricted cash at beginning of period	18,349	9,460
Cash, cash equivalents and restricted cash at end of period	54,192	28,297
Supplemental disclosure of non-cash financing activities:
Conversion of convertible preferred stock into common stock	41,466	0
Supplemental Cash Flow Information:
Cash paid for interest	1,495	0
Cash paid for income taxes	$ 0	$ 0