CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating activities:
Net loss	$ (27,386)	$ (24,694)
Non-cash adjustments reconciling net loss to operating cash flows:
Depreciation of property and equipment	100	116
Amortization of premium on investments	251	313
Share-based compensation expense	5,108	2,231
Change in fair value of warrant liability	0	6,451
Restructuring costs	0	13
Changes in operating assets and liabilities:
Other current assets	1,338	401
Other long-term assets	38	(24)
Accounts payable, accrued liabilities and other long-term liabilities	1,737	649
Cash flows used for operating activities	(18,814)	(14,544)
Investing activities:
Purchases of property and equipment	(297)	(264)
Purchases of short-term investments	(41,024)	(5,941)
Disposal and maturities of short-term investments	17,980	14,593
Cash flows (used for) provided by investing activities	(23,341)	8,388
Financing activities:
Proceeds from sale of common stock, net	48,361	0
Proceeds from exercise of common stock options	330	436
Proceeds from stock issuances under employee stock purchase plan	250	0
Cash flows provided by financing activities	48,941	436
Increase (decrease) in cash and cash equivalents	6,786	(5,720)
Cash and cash equivalents, beginning of period	6,593	14,235
Cash and cash equivalents, end of period	13,379	8,515
Fixed asset additions included within accounts payable	$ 0	$ 21