Annual report pursuant to Section 13 and 15(d)

CONSOLIDATED STATEMENTS OF CASH FLOWS

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net loss	$ (54,010)	$ (47,743)	$ (29,818)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,527	1,273	602
Loss on disposal of assets		4	17
Stock-based compensation expense	4,419	4,234	3,233
Net amortization of premiums and discounts on marketable securities	(102)	6
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	131	(508)	(390)
Accounts receivable	867	(317)
Other long-term assets	(365)	(482)
Restricted cash			(413)
Accounts payable	141	(404)	2,022
Accrued expenses	3,533	3,685	1,663
Deferred revenue	(550)
Deferred rent and lease incentive	(320)	(284)	54
Net cash used in operating activities	(44,729)	(40,536)	(23,030)
Investing activities
Purchases of property and equipment	(821)	(2,322)	(1,176)
Purchases of marketable securities	(41,770)	(25,020)
Sales or maturities of marketable securities	27,000
Net cash used in investing activities	(15,591)	(27,342)	(1,176)
Financing activities
Payments on capital lease obligations	(168)	(135)	(50)
Proceeds from issuance of common stock through employee benefit plans	1,799	395	392
Proceeds from issuance of convertible preferred stock, net of issuance costs		39,813
Proceeds from issuance of common stock, net of issuance costs	32,306	50,484	(620)
Net cash provided by (used in) financing activities	33,937	90,557	(278)
(Decrease) increase in cash and cash equivalents	(26,383)	22,679	(24,484)
Cash and cash equivalents, Beginning of period	58,588	35,909	60,393
Cash and cash equivalents, End of period	32,205	58,588	35,909
Supplemental disclosure of cash flow information:
Cash paid for interest	9	19	18
Non-cash investing and financing activities
Conversion of convertible preferred stock into common stock		82,013
Property and equipment received but unpaid as of period end	143	349	1,359
Assets acquired under capital lease		$ 17	389
Assets acquired through lease incentive			1,612
Offering costs incurred but unpaid as of period end	$ 13		$ 1,280