Why wasn’t the Delta F508 mutation chosen for the Phase 2 VX-770 clinical trial?
Because the protein resulting from the G551D mutation is already located at the cell surface, these patients have the greatest potential to benefit from treatment with VX-770. Most Delta F508 protein is not at the cell surface and therefore it is unclear whether the patients with this mutation will benefit. The Phase 3 registration program of VX-770 will help determine if it is effective in this patient population. Vertex is also developing VX-809, which is designed to increase the concentration of CFTR proteins at the cell surface. VX-809 is currently being studied, alone and in combination with VX-770, in a clinical trial that will test the safety of both drugs in patients with two copies of the Delta F508 mutation. Research in the laboratory has shown that using two therapies in combination may increase CFTR function in Delta F508 cells, compared with using one therapy alone.
