CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating Activities:
Net loss	$ (100,864)	$ (135,414)
Reconciliation of net loss to net cash used in operating activities:
Depreciation and amortization	4,744	6,177
Loss (Gain) on disposal of property and equipment	88	(55)
Gain on Catalent transaction	(9,016)	0
Non-cash impact of lease termination	0	(4,381)
Amortization of debt issuance costs	1,068	1,068
Non-cash stock-based compensation	12,803	13,928
Other	1,269	(1,820)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	1,326	1,692
Accounts payable and accrued expenses	(16,882)	(10,498)
Deferred revenue	(7,416)	(10,256)
Net cash used in operating activities	(112,880)	(139,559)
Investing Activities:
Capital expenditures	(1,641)	(855)
Proceeds from Catalent transaction	18,333	0
Proceeds from maturities of marketable securities	39,500	98,305
Purchases of marketable securities	(17,484)	(117,172)
Net cash provided by (used in) investing activities	38,708	(19,722)
Financing Activities:
Net proceeds from sales of common stock	67,220	96,486
Proceeds from the exercise of stock options and employee stock purchases	992	2,462
Net cash provided by financing activities	68,212	98,948
Effect of exchange rate on cash, cash equivalents and restricted cash	(69)	(62)
Net decrease in cash, cash equivalents and restricted cash	(6,029)	(60,395)
Cash, cash equivalents and restricted cash at beginning of period	81,959	135,431
Cash, cash equivalents and restricted cash at end of period	75,930	75,036
Supplemental disclosure of non-cash activities:
Sale of common stock under the Sales Agreement not settled at quarter-end	610	0
Property and equipment purchases included in accounts payable and accrued expenses	183	126
Supplemental disclosure of cash flow information:
Cash payments of interest	$ 12,188	$ 12,188