Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 162,382	$ 65,726
Restricted cash	304	200
Prepaid expenses and other current assets	1,687	1,505
Total current assets	164,373	67,431
Property and equipment, net	3,614	3,145
Other assets	20	219
Total assets	168,007	70,795
Current liabilities:
Accounts payable	4,173	6,652
Accrued clinical and other expenses	590	1,029
Accrued payroll and related expenses	910	2,077
Total current liabilities	5,673	9,758
Shareholders’ equity:
Common Stock, $0.0001 par value; 100,000,000 shares authorized, 22,123,456 and 18,261,557 shares issued and outstanding at March 31, 2017 and December 31, 2016, respectively	2	2
Additional paid-in capital	785,640	661,103
Accumulated deficit	(629,951)	(606,711)
Total shareholders’ equity	162,334	61,037
Total liabilities and shareholders’ equity	168,007	70,795
Series C-1 Convertible Preferred Stock [Member]
Shareholders’ equity:
Convertible preferred stock, value	3,906	3,906
Series F Convertible Preferred Stock [Member]
Shareholders’ equity:
Convertible preferred stock, value	$ 2,737	$ 2,737