Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Operating activities:
Net loss	$ (9,622)	$ (10,408)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	48	101
Noncash interest expense	56	45
Financing derivative	3
Amortization of premium on marketable securities	80	59
Stock based compensation expense	305	491
Modification of stock options related to executive severance	389
Modification of stock options related to restructuring activities	414
Changes in operating assets and liabilities:
Contract receivables		40
Prepaid expenses and other assets	583	(138)
Accounts payable	(965)	(1,563)
Accrued compensation	(133)	(454)
Accrued research and clinical liabilities	(159)	382
Other liabilities	(13)	155
Deferred rent	(1)	(8)
Net cash (used in) operating activities	(9,015)	(11,298)
Investing activities:
Purchase of marketable securities	(3,703)	(31,005)
Proceeds from maturities of marketable securities	15,822	22,460
Purchases of property and equipment	(108)	(35)
Change in restricted cash		(193)
Net cash provided by (used in) investing activities	12,011	(8,773)
Financing activities:
Proceeds from issuance of common stock		59
Principal payments under notes payable	(1,295)	(811)
Net cash (used in) provided by financing activities	(1,295)	(752)
Net increase (decrease) in cash and cash equivalents	1,701	(20,823)
Cash and cash equivalents, beginning of period	10,923	54,220
Cash and cash equivalents, end of period	12,624	33,397
Supplemental cash flow disclosure:
Cash paid for interest	$ 233	$ 219