Vertex Pharmaceuticals Inc. (VRTX) recently released positive interim data from the first part of a phase II study evaluating the combination regimen of VX-770 and VX-809, for the treatment of cystic fibrosis (CF).
Despite the encouraging data, the company’s share price witnessed a decline due to investors’ high expectations from the combination drug following Vertex Pharma’s announcement of statistically significant data on VX-770 in February.
Vertex Pharma is currently studying both VX-770 and VX-809 for the treatment of CF, and the phase II study is primarily meant to assess the safety and tolerability, as well as the effect of the combination drug on cystic fibrosis transmembrane conductance regulator (CFTR) function, as measured by sweat chloride.
The first part of the study enrolled 62 patients with two copies of the F508del mutation in the CF gene. The study had three treatment arms in its first part. The study regimen involved treating with VX-809 (200 mg) or placebo alone for 14 days, followed by VX-809 (200 mg) in combination with VX-770 (150 mg or 250 mg) or placebo for the next 7 days.
The CFTR protein does not reach the cell surface in normal amounts in patients with the F508del mutation. This leads to an increase in the amount of mucus and other complications that can damage the lung. We note that VX-809 helps the protein reach the cell surface, while VX-770 helps the protein function normally once it reaches the cell surface.
The first part of the study met its two primary endpoints of demonstrating safety and tolerability of the combination regimen and the effect of the VX-770 and VX-809 combination on CFTR function as measured by sweat chloride, which is a key measure of the CFTR protein function.
Vertex Pharma plans to initiate the second part of the study in the fourth quarter of 2011, after it completes further analyses of the first part data.
Besides further evaluating the effect of the combined multiple doses of VX-770 and VX-809 on sweat chloride measurements, the second part of the study would also assess longer dosing periods for the combination drug.
Our View
We currently have a Neutral recommendation on Vertex Pharma, which carries a Zacks #3 Rank (short-term Hold rating). We are pleased with the interim data on the combination drug of VX-770 and VX-809, as only one other company PTC Therapeutics, Inc. is developing a treatment for CF.
PTC Therapeutics’ ataluren, which is currently in late-stage trial is being developed in collaboration with Genzyme, now a part of Sanofi-Aventis (SNY).
