| Net loss | |
| Depreciation of property and equipment | |
| Stock-based compensation | 16.77M |
| Amortization of deferred license fees | |
| Warrant licensing expense | |
| Prepaid expenses and other current assets | 1.7M |
| Accounts payable | -973K |
| Accrued expenses | 5.45M |
| Accrued interest | 0 |
| Net cash used in operating activities | |
| Purchases of marketable securities | -151.46M |
| Maturities of marketable securities | 142.81M |
| Purchases of property and equipment | -12.17M |
| Net cash used in investing activities | |
| Proceeds from Genzyme Collaboration, License and Purchase Agreement | |
| Proceeds from sale of common stock, net of issuance costs | 144.25M |
| Proceeds from exercise of common stock options and stock purchase plan | 1.05M |
| Net cash provided by financing activities | |
| Net (decrease) increase in cash and cash equivalents | 22.31M |
| Cash and cash equivalents, beginning of period | 41.14M |
| Cash and cash equivalents, end of period | 63.45M |
| Unrealized gain on available-for-sale investments | 410K |
| Issuance of 27,872 and 15,460 shares of common stock to fund the Company's 401(k) matching contribution for 2010 and 2009, respectively | |