Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current Assets:
Cash and cash equivalents	$ 13,345	$ 35,781
Marketable securities	94,776	57,580
Prepaid expenses and other current assets	593	1,034
Total current assets	108,714	94,395
Property and Equipment, at cost:
Laboratory equipment	4,051	2,314
Office and computer equipment	824	729
Leasehold improvements	283	288
Furniture and fixtures	28	23
Property and Equipment, gross	5,186	3,354
Less-Accumulated depreciation and amortization	(1,781)	(796)
Property and Equipment, net	3,405	2,558
TOTAL ASSETS	112,119	96,953
Current Liabilities:
Accounts payable	3,652	765
Accrued expenses	3,327	3,069
Capital lease obligation, current portion	333
Deferred license fees, current portion	4,143	4,143
Total current liabilities	11,455	7,977
Long term debt	1,000	1,000
Long term accrued interest	63	42
Capital lease obligation, less current portion	711
Deferred license fees, less current portion	295	4,439
Commitments and contingencies
Stockholders' Equity:
Preferred stock, $0.01 par value Authorized-5,000,000 shares Issued and outstanding-none at December 31, 2012 and 2011
Common stock, $0.01 par value Authorized-100,000,000 shares Issued and outstanding-63,909,800 and 56,624,763 shares at December 31, 2012 and 2011, respectively	639	566
Additional paid-in capital	372,123	304,767
Other comprehensive income (loss)	78	(14)
Accumulated deficit	(274,245)	(221,824)
Total stockholders' equity	98,595	83,495
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 112,119	$ 96,953