Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows from Operating Activities:
Net loss	$ (53,317)	$ (60,411)	$ (58,981)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	235	193	161
Stock-based compensation expense	5,359	4,325	3,875
Issuance of common stock in consideration for rights granted under the Aurigene collaboration agreement (see Note 3(b))	0	17,989	23,968
Amortization of debt issuance costs	144	48	56
Non-cash interest (income)/expense	(53)	168	149
Gain on sale of fixed assets	0	0	(22)
Changes in operating assets and liabilities:
Accounts receivable	(614)	(353)	(145)
Prepaid expenses and other assets	267	(85)	(726)
Accounts payable and accrued and other liabilities	(376)	2,315	1,774
Total adjustments	4,962	24,600	29,090
Net cash used in operating activities	(48,355)	(35,811)	(29,891)
Cash Flows from Investing Activities:
Purchases of investments	(51,121)	(57,639)	(123,240)
Sales/maturities of investments	47,679	88,092	116,822
Decrease in restricted cash/investments	0	0	14
Expenditures for property and equipment	(188)	(329)	(48)
Proceeds from sale of fixed assets	0	0	24
Net cash (used in)/provided by investing activities	(3,630)	30,124	(6,428)
Cash Flows from Financing Activities:
Proceeds from issuance of common stock associated with offerings, net of issuance costs (see Note 11)	41,546	0	64,620
Proceeds from issuance of common stock under the Company’s share-based compensation plans	1,138	2,907	1,206
Proceeds from new credit agreement with HealthCare Royalty	45,000	0	0
Payment of debt issuance costs	(192)	0	0
Payment on termination of former credit agreement with BioPharma	(18,303)	0	0
Payments made on Curis Royalty’s debt	(4,954)	(4,273)	(4,163)
Net cash provided by/(used in) financing activities	64,235	(1,366)	61,663
Net increase/(decrease) in cash and cash equivalents	12,250	(7,053)	25,344
Cash and cash equivalents, beginning of period	26,038	33,091	7,747
Cash and cash equivalents, end of period	38,288	26,038	33,091
Supplemental cash flow data:
Cash paid for interest	$ 3,942	$ 2,787	$ 3,303