Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net loss	$ (17,385)	$ (6,217)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	486	130
Stock-based compensation	1,544	112
Amortization of premiums and discounts on marketable securities	(192)
Loss on disposal of property and equipment	97
Changes in operating assets and liabilities
Prepaid expenses & other current assets	(1,333)	(965)
Other assets	61	1
Accounts payable & accrued liabilities	1,628	443
Other liabilities, current	(9)	(2)
Deferred rent	(216)	5
Net cash used in operating activities	(15,319)	(6,493)
Cash flows from investing activities:
Purchases of property and equipment	(1,003)	(326)
Purchases of marketable securities	(72,995)
Proceeds from sale of property and equipment	10
Net cash used in investing activities	(73,988)	(326)
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs	77,695
Proceeds from issuance of preferred stock, net of issuance costs		49,755
Proceeds from the exercise of stock options	213
Net cash provided by financing activities	77,908	49,755
Effect of exchange rate changes on cash and cash equivalents and restricted cash	(53)	42
Net (decrease) increase in cash, cash equivalents and restricted cash	(11,452)	42,978
Cash, cash equivalents and restricted cash at the beginning of period	51,046	9,760
Cash, cash equivalents and restricted cash at the end of period	39,594	52,738
Supplemental disclosures of noncash financing information:
Reclassification of employee stock liability to equity upon vesting	29	$ 14
Addition of tenant improvement paid by landlord	2,703
Purchase of property and equipment in accounts payable	7
Conversion of redeemable convertible preferred stock into common stock	$ 77,931