Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 9,710	$ 13,345
Marketable securities	138,131	94,776
Prepaid expenses and other current assets	904	593
Total current assets	148,745	108,714
Property and Equipment, at cost:
Laboratory equipment	4,546	4,051
Assets under construction	3,668
Office and computer equipment	855	824
Leasehold improvements	339	283
Furniture and fixtures	28	28
Property and Equipment, gross	9,436	5,186
Less-Accumulated depreciation	(2,685)	(1,781)
Property and Equipment, net	6,751	3,405
TOTAL ASSETS	155,496	112,119
Current Liabilities:
Accounts payable	605	3,652
Accrued expenses	5,725	3,327
Capital lease obligation, current portion	347	333
Lease incentive obligation, current portion	495
Deferred license fees, current portion	1,330	4,143
Total current liabilities	8,502	11,455
Long-term debt	1,000	1,000
Long-term accrued interest	79	63
Capital lease obligation, less current portion	449	711
Lease incentive obligation, less current portion	376
Deferred license fees, less current portion		295
Commitments and contingencies
Stockholders' Equity:
Preferred stock, $0.01 par value Authorized-5,000,000 shares Issued and outstanding-no shares at September 30, 2013 and December 31, 2012
Common stock, $0.01 par value Authorized-100,000,000 shares Issued and outstanding-70,897,521 and 63,909,800 shares at September 30, 2013 and December 31, 2012	709	639
Additional paid-in capital	452,836	372,123
Other comprehensive income	118	78
Accumulated deficit	(308,573)	(274,245)
Total stockholders' equity	145,090	98,595
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 155,496	$ 112,119