Phase 2 Study of VX-770 and VX-809 Combination Regimens for Cystic Fibrosis

Vertex Pharmaceuticals announced positive interim results from the first part of a Phase 2 study evaluating multiple combination regimens of VX-770 and VX-809, two investigational agents designed to treat the defective protein that causes cystic fibrosis (CF). The study enrolled and randomized 62 people with two copies of the most common mutation in the CF gene, known as the F508del mutation. Interim analysis demonstrates that the study met its two primary endpoints: safety and tolerability of the combination regimen and the effect of the combination of VX-770 and VX-809 on CFTR function as measured by sweat chloride. In the arm that evaluated VX-809 (200mg) followed by dosing of VX-770 (250mg) in combination with VX-809, a statistically significant reduction in sweat chloride of -13.17mmol/L (P<0.001) was observed from baseline (Day 0) through Day 21. In this arm, a -9.10mmol/L (P<0.001) reduction was observed after VX-770 (250mg) was added to VX-809 (200mg) for seven days (Day 14–21).

The cystic fibrosis transmembrane conductance regulator (CFTR) protein is responsible for regulating the flow of chloride across the cell surface to help hydrate and clear mucus from the airways. CF results from a defect in the CFTR protein. VX-809, a CFTR corrector, aims to increase CFTR function by increasing the movement of CFTR to the cell surface. Once these proteins are on the cell surface, VX-770, a CFTR potentiator, increases the function of the proteins by increasing their ability to transport ions across the cell membrane.

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