Experimental Oral Protease Inhibitor VX-950 from Vertex Produces Rapid and Dramatic Reduction in HCV RNA in Combination with Pegylated Interferon Alfa-2a (Pegasys)

New data announced on January 9, 2006 by Vertex Pharmaceuticals
show that VX-950, an experimental oral hepatitis C virus (HCV) protease inhibitor, dosed in combination with pegylated interferon alfa-2a (Pegasys), achieved a rapid and dramatic reduction (median 5.5 log10) in plasma viral RNA levels in patients with chronic genotype 1 HCV infection. Following are excerpts from the text of the statement by Vertex:

In this Phase Ib study, the combination of VX-950 and Pegasys produced an initial median reduction in plasma HCV RNA of more than 3 log10 in the first two days, followed by continued decline to a median 5.5 log10 reduction in HCV RNA at day 14, which equates to a 300,000-fold reduction in viral levels.

The majority of patients (6 of 8) receiving the combination achieved HCV RNA levels below the limit of quantitation (30 IU/mL, as measured by the Roche TaqMan(R) assay) at 14 days, with 4 of 8 patients achieving HCV RNA levels below the limit of detection (10 IU/mL, Roche TaqMan).

The antiviral activity of the combination through 14 days was significantly greater than the activity of VX-950 administered as a single agent, and much greater than Pegasys alone. In addition, VX-950 appeared to be well-tolerated when dosed alone and in combination with Pegasys in the study. The full data set will be presented at a medical conference later this year.

These data show that VX-950, in combination with pegylated interferon, produced a very rapid viral response in each of these genotype 1 patients, who are historically the most difficult to treat effectively," said Henk W. Reesink, MD, Associate Professor of Medicine at Academic Medical Center in Amsterdam, and a lead investigator for the study. "The profound decreases in viral load strongly support the evaluation of VX-950 in combination with pegylated interferon as part of a three-month treatment paradigm to achieve sustained viral responses (SVR) in HCV patients."


Study Design and Results

The 14-day, randomized, blinded, placebo-controlled Phase Ib study enrolled 20 treatment-naive patients with genotype 1 HCV, the most prevalent and difficult to treat form of HCV infection.

Patients were randomized to receive a new tablet formulation of VX-950 at a dose of 750 mg every eight hours (q8h) in combination with a standard dose of Pegasys (n=8), the same dose of VX-950 administered alone (n=8), or a standard dose of Pegasys alone (n=4).

The median viral load for all patients at study entry was 6.65 log10 IU/mL HCV RNA approximately 4.4 million IU/mL). Available interim results indicate:

  • Median 5.5 log10 reduction in HCV RNA in patients receiving VX-950 and Pegasys for 14 days; 6 of 8 patients had viral levels below the limit of quantitation (30 IU/mL) at 14 days, and 4 of 8 also achieved viral levels below the limit of detection (10 IU/mL).
  • Median 4.0 log10 reduction in HCV RNA in patients receiving VX-950 alone for 14 days; 1 of 8 patients had viral levels below the limit of detection (10 IU/mL).
  • Median 1.0 log10 reduction in HCV RNA in patients receiving Pegasys alone for 14 days; no patients had viral levels below the limit of quantitation (30 IU/mL) at 14 days.

Safety

A preliminary safety review has been conducted that indicates that the treatment was well tolerated. All patients completed dosing and no serious adverse events were reported. All adverse events in the patients receiving VX-950 alone were reported as mild.

Typical interferon-related side effects, of mild to moderate severity, were reported in the patients that received Pegasys along with VX-950 or placebo. In addition, laboratory-related adverse events of neutropenia in one patient and thrombocytopenia in one patient were reported among the patients who received Pegasys.

Neutropenia and thrombocytopenia have previously been reported in patients receiving Pegasys alone. It is not known if the two patients in whom these events occurred were also receiving VX-950, because the full safety database has not yet been unblinded. A complete safety analysis will be conducted once the study is fully unblinded.

"The data announced today provide further support for VX-950's potential to transform the standard of care in HCV," said Joshua Boger, Ph.D., Chairman, President and Chief Executive Officer of Vertex. "We look forward to pursuing additional clinical studies in 2006 that will evaluate the ability of VX-950, in combination with pegylated interferon, to achieve sustained viral responses in HCV patients, with a shorter duration of treatment compared to the current standard of care."

Clinical Plans

Vertex is conducting a broad Phase II development program designed to establish the safety and antiviral activity of VX-950 in studies of up to three months duration. In the next few months, Vertex expects to initiate a three-month Phase II trial with more than 200 participants that will study VX-950 dosed in combination with Pegasys, both with and without ribavirin, another standard HCV treatment.

This three-month study will include a comparison to the current standard of care in HCV treatment. Additionally, a 12-patient, 28-day Phase II trial of VX-950 plus Pegasys and ribavirin has now completed enrollment and preliminary data from this study are anticipated in the first quarter [of 2006]. In December 2005, VX-950 received Fast Track designation from the U.S. Food and Drug Administration.

About VX-950 and Previous Clinical Data

VX-950 is an oral inhibitor of hepatitis C virus protease, an enzyme essential for viral replication. In 2005, Vertex reported results from a 14-day, Phase Ib study of VX-950 dosed as a single agent in genotype 1 HCV patients. In this prior study, VX-950 displayed potent antiviral activity.

After 14 days of dosing, patients in the dose group with the best response (750 mg every 8 hours) achieved a median reduction in HCV RNA of 4.4 log10, a 25,000-fold reduction in viral levels.

Adverse events observed in patients receiving VX-950 that were considered possibly related to the drug were mild, and generally similar in frequency to events in patients receiving placebo. The most common adverse events reported in both placebo and VX-950 patients were headache, frequent urination and
gastrointestinal symptoms.

Vertex researchers were the first to solve the three-dimensional crystal structure of HCV protease, and have used structural insights to enable the design of small molecule HCV protease inhibitors, including VX-950.

For more information about Vertex, visit www.vrtx.com

Articles about VX-950 on HIV and Hepatitis.com TOP

01/10/05

Source
Vertex Pharmaceuticals.  VX-950, Investigational Oral Hepatitis C Protease Inhibitor, Demonstrates Rapid and Dramatic Reduction in Viral Levels in Combination with Pegylated Interferon. Press Release. January 9, 2006.