Today, patients with cystic fibrosis (CF) lead longer, healthier lives than ever before. But a "longer, healthier" life for a CF patient still means living, on average, only into their mid-thirties while enduring hours of daily therapy.

Approximately 30,000 people in the U.S. are afflicted with CF, an orphan, genetic disease where patients have defective or missing cystic fibrosis transmembrane conductance regulator (CFTR) proteins. When these CFTR proteins cannot properly move chloride ions across the cell membrane, mucus builds in the lungs, causing an environment prone to infection, inflammation and a gradual loss of lung function.

Current CF therapies aim to treat only the complications arising from CF, such as lung infections, and while these therapies have improved the lives of CF patients, the median predicted lifespan for those afflicted with CF remains only 37 years.

A BOLD ENDEAVOR TO TREAT CF AT ITS ROOT
In 1998, Vertex and the Cystic Fibrosis Foundation began a bold endeavor to discover and develop novel CF therapies aimed at treating the underlying defect of CF. Twelve years later, Vertex is advancing two novel CF compounds through clinical development: VX-770, known as a CFTR potentiator, and VX-809, known as a CFTR corrector.

VX-770 aims to increase the activity of defective CFTR proteins at the cell surface. In a Phase 2 trial in 39 patients with the G551D mutation in the CFTR gene completed in 2008, treatment with VX-770 for 14 or 28 days resulted in improvement in lung function as measured by forced expiratory volume (FEV1), as well as improvement in additional biomarkers of CFTR activity. Based on these results, a Phase 3 registration program is ongoing focused on patients with the G551D mutation, which accounts for approximately 4% of the U.S. CF patient population. Should these studies be successful, Vertex plans to submit a New Drug Application for VX-770 in the second half of 2011.

VX-809 aims to increase the concentration of CFTR proteins at the cell surface. In a Phase 2 trial completed in 2009 in 89 patients with the most common mutation in the CFTR gene, known as F508del, treatment with VX-809 for 28 days resulted in improvement in measures of sweat chloride, a key biomarker of CFTR activity.

Based on these results, Vertex is evaluating the potential development path for a combination regimen of VX-770 and VX-809 in patients with the F508del mutation, which is present in approximately 90% of the CF patient population in the U.S.

Please visit investors.vrtx.com for additional clinical data on Vertex's Phase 2 trials with VX-770 and VX-809, including safety information. These materials include forward-looking statements; please refer to the Safe Harbor statement on the accompanying annual report.