Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019		Mar. 31, 2018
Operating activities
Net loss	$ (26,144)		$ (17,019)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	675		674
Amortization of deferred financing costs	120		14
Amortization of deferred compensation for services	76		50
Amortization of premium on investment securities	(301)		(75)
Non-cash lease expense	439
Stock-based compensation	1,922		2,425
Change in derivative liabilities	37
Non-cash interest associated with debt discount accretion	113
Changes in operating assets and liabilities:
Accounts receivable and unbilled license revenue	5,078		10,796
Prepaid expenses and other assets	333		2,005
Accounts payable	777		(2,117)
Accrued compensation and benefits	(1,089)		(1,612)
Accrued and other liabilities	1,051		(1,945)
Net cash used in operating activities	(16,913)		(6,804)
Investing activities
Proceeds from maturities of investments	55,020		37,085
Sales and redemptions of investments			850
Purchases of investments	(24,874)		(39,015)
Purchases of property and equipment	(165)		(55)
Net cash provided by (used in) investing activities	29,981		(1,135)
Financing activities
Issuance of common stock upon exercise of options	2
Proceeds from issuance of common stock under stock plans	198		301
Net cash provided by financing activities	200		301
Net increase (decrease) in cash and cash equivalents	13,268		(7,638)
Cash and cash equivalents at beginning of period	78,768	[1]	75,383
Cash and cash equivalents at end of period	$ 92,036		$ 67,745

[1] Derived from the audited consolidated financial statements included in the Company’s Annual Report on Form 10K for the year ended December 31, 2018.