Vertex Pharmaceuticals Inc. (VRTX) recently reported positive interim data from a mid-stage trial of hepatitis C virus (HCV) treatment, VX-222. The phase II trial, ZENITH, is being conducted to evaluate the safety and tolerability of VX-222 and telaprevir (lead pipeline candidate, being studied for HCV), in combination with pegylated-interferon and ribavirin, in treatment naïve patients with genotype 1 chronic hepatitis C.

The study data demonstrated that 90% patients who were dosed VX-222 (400 mg) in combination with telaprevir, pegylated-interferon and ribavirin had undetectable HCV after 12 weeks of treatment. Half of the patients from the aforesaid arm were eligible to stop all treatment at week 12, while the rest were dosed pegylated-interferon and ribavirin alone for another 12 weeks.

The ZENITH study, which enrolled 106 patients with HCV, initially constituted of 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 (400 mg or 100 mg) and telaprevir (1,125 mg). Both these study arms were discontinued due to a pre-defined stopping rule related to viral breakthrough. Arms C and D are currently in progress and designed to evaluate the four-drug combination regimens of VX-222 (400 mg and 100 mg), telaprevir (1,125 mg), pegylated-interferon and ribavirin. An additional treatment arm has been added to the study to evaluate a three-drug regimen of VX-222, telaprevir and ribavirin in people with genotype 1b chronic hepatitis C. This study arm is presently enrolling patients. A sixth arm may be added to the study as per protocol based on data from the study.

We note that telaprevir is presently under regulatory review in the US for the treatment of HCV. The US Food and Drug Administration (FDA) has set May 23, 2011, as the target date for telaprevir.

Vertex Pharma has a partnership agreement with Johnson & Johnson (JNJ) for the development and commercialization of telaprevir outside the US. Vertex Pharma has retained the US rights to the drug.

We currently have a Neutral recommendation on Vertex Pharma, which is supported by a Zacks #3 Rank (short-term Hold rating).

 
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