Vertex Pharmaceuticals Inc. (VRTX) recently reported positive interim data from two treatment arms (E and F) of a mid-stage study (:ZENITH) of VX-222, when dosed in combination with Incivek (telaprevir) and ribavirin in treatment-naïve patients with genotype 1 (1a and 1b) hepatitis C virus (:HCV).
Each arm (E and F) of the ZENITH study, which consisted of 23 patients, was conducted to determine whether a patient was eligible to stop all treatment at 12 weeks. The trial results demonstrated that eleven patients met the criteria of having undetectable HCV at weeks two and eight and were therefore eligible to stop all treatment at week 12 week.
We note that on the basis of these data, Vertex Pharma plans to commence a phase IIb study to evaluate treatment with VX-222 in combination with Incivek and ribavirin for 12 weeks in treatment-naïve patients with genotype 1 HCV.
The ZENITH study, which enrolled 152 patients with HCV, initially constituted four treatment arms (A, B, C and D) evaluating two-drug and four-drug combination regimens. The primary endpoint of the study is safety and tolerability.
The secondary endpoint is not only on-treatment antiviral activity but also determining the proportion of people in each treatment arm who achieve a sustained viral response (SVR, defined as undetectable HCV 24 weeks after the end of treatment).
The arms A and B of the study were two-drug combination regimens of VX-222 and Incivek. Both these study arms were discontinued due to a pre-defined stopping rule related to viral breakthrough. Arms C and D were designed to evaluate the four-drug combination regimens of VX-222, Incivek, pegylated-interferon and ribavirin. Last year in November, Vertex Pharma reported positive data from arms C and D of the study.
The treatment arms (E and F) were added to the study later to evaluate a three-drug, all-oral, interferon-free regimen of VX-222, Incivek and ribavirin.
Incivek is currently marketed in the US and Canada for the treatment of HCV. The drug is available as Incivo outside the US and the Far East and as Telavic in Japan.
We currently have a Neutral recommendation on Vertex Pharma. The stock carries a Zacks #3 Rank (Hold rating) in the short-run.
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