Pegasys Shows Efficacy In Chronic HCV Patients With Cirrhosis


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DALLAS, TX -- November 8, 1999 -- In the largest prospective study to include only hepatitis C patients with cirrhosis, Pegasys™ (peginterferon alfa-2a) may achieve a sustained response rate nearly five times higher than standard interferon. This data, presented at the 50th annual meeting of the American Association for the Study of Liver Diseases (AASLD), comes at a time when liver failure due to chronic hepatitis C and related cirrhosis is the leading cause of liver transplants in the United States.

The data from a randomized, controlled, multicenter Phase II/III trial found that in an intent-to-treat analysis, 29 percent (n=87) of cirrhotic patients treated with 180 mcg. of once-weekly Pegasys, an investigational interferon alfa-2a, experienced a sustained response of undetectable levels of hepatitis C virus (HCV) compared to 6 percent of patients (n=88) treated with currently marketed interferon. Sustained response is measured at 24 weeks following a treatment period of 48 weeks. The presence of HCV was measured by the Roche Diagnostics Amplicor® HCV Test V2.0.

"This study is an important step forward in finding a treatment that provides a higher response rate than currently available interferons for hepatitis C patients with cirrhosis," said Dr. E. Jenny Heathcote, Professor of medicine, University of Toronto, and gastroenterologist, University Health Network, Toronto Western Hospital, in Toronto, ON.

The Phase II/III cirrhotic study followed 271 HCV-infected patients with cirrhosis for a total of 72 weeks -- 48 weeks of treatment followed by a 24-week post-treatment follow-up. Patients were randomized to one of two groups to receive once-weekly doses of 90 mcg. or 180 mcg. of Pegasys or three million international units (MIU) of interferon three times per week.

In the Phase II/III cirrhotic study, adverse events with Pegasys were similar to those seen with traditional interferon regimens, such as fatigue, headache, myalgia/arthralgia, flu-like symptoms, nausea/vomiting, injection site reactions, fever, chills, diarrhea, partial alopecia, abdominal pain, depression, irritability, insomnia, dizziness and anorexia. Dose modification was required for thrombocytopenia in six percent, 18 percent and 19 percent and for neutropenia in 14 percent, nine percent and 11 percent of patients in the interferon, 90 mcg. and 180 mcg. Pegasys groups respectively.

Cirrhosis of the liver can permanently injure and scar the liver, decreasing the amount of normal functioning liver tissue. Moreover, the scar tissue interferes with the flow of blood through the liver, further interfering with normal liver function. Approximately 20 percent of people with hepatitis C-at least 780,000 Americans-are expected to develop cirrhosis within 10 to 20 years.

Earlier this year, results from a Phase II study of 155 non-cirrhotic, hepatitis C-infected patients were presented during Digestive Disease Week.

The study found that 36 percent of patients treated with 180 mcg. of Pegasys experienced a sustained response of undetectable levels of hepatitis C.

Adverse events experienced during the Phase II study with Pegasys appear to be similar to those seen with traditional interferon regimens.

Sizing Up the "PEG" in Pegasys

Pegylation is the process of attaching one or more chains of polyethylene glycol (also known as PEG) to another molecule. In Pegasys, a large, branched, mobile PEG is covalently bound to the interferon alfa-2a molecule and provides a selectively protective barrier. Pharmacokinetic behavior depends on the length of the PEG and the structure of the link between the PEG moiety and the protein. Researchers believe the PEG creates a barrier that shields the interferon alfa-2a from being eliminated from the body too rapidly and maintains its ability to suppress the hepatitis C virus.

The large, branched PEG in Pegasys is designed to increase solubility and duration of the virus' exposure to the drug, which may account for the elimination of large "peak-to-trough" fluctuations experienced with standard interferon. As a result, the increased sustained response rate and tolerability of Pegasys may be enhanced, leading to constant viral suppression and a reduction in the incidence and severity of peak-related side effects.

The high molecular weight (40 kilodalton) branched PEG in Pegasys-is believed to provide sustained pegylated interferon alfa-2a exposure at clinically effective levels. Results of a pharmacokinetics (PK) study, which was also presented at the AASLD meeting, revealed that sustained delivery of Pegasys occurs with maximum concentrations reached at 80 hours, with substantial concentrations seen 3 to 8 hours after dosing. The study suggests that a PEG that weighs 40 kilodaltons (40k) results in sustained concentrations throughout the dosing interval, and reduced clearance of Pegasys versus standard interferon. Administered once weekly, the therapeutic concentrations of Pegasys last throughout one full week. In contrast, interferons with smaller PEGs are excreted quickly by the kidneys, requiring more frequent dosing, according to earlier Roche studies.

First Results on Pegasys with Ribavirin
Results of a study to evaluate Pegasys 180 mcg. in combination with ribavirin 1000-1200mg, may indicate positive antiviral activity and good tolerability. In this Phase II pilot study also presented at AASLD, a once-weekly dose of Pegasys was administered to 20 patients with chronic hepatitis C, in combination with 1000-1200 mg oral ribavirin twice daily, for 24 to 48 weeks, followed by a 24-week post-treatment follow-up. At week 48 of the study, 70 percent of patients (14/20) had undetectable levels (less than 100 copies/mL) of HCV in their blood. Adverse events with Pegasys/ribavirin combination therapy were mild to moderate in severity. Four patients experienced severe adverse events. Larger studies to further evaluate the use of Pegasys in combination with ribavirin are ongoing.

Ribavirin therapy is contraindicated in women who are pregnant and in the male partners of women who are pregnant. Extreme care must be taken to avoid pregnancy during therapy and for six months after completion of treatment in female patients, and in female partners of male patients who are taking combination ribavirin/interferon therapy. Women of childbearing potential and men must use two reliable forms of effective contraception during treatment and during the six-month post-treatment follow-up period. Significant teratogenic and/or embryocidal effects have been demonstrated for ribavirin in all animal species studied.

"The current body of data on Pegasys monotherapy shows that it may be a treatment option that provides better tolerability and higher response rates for hepatitis C patients with and without cirrhosis," said Dr. Chris Pappas, medical director at Hoffmann-La Roche. "Recognizing that ribavirin is another antiviral proven effective in combination with interferon, Roche is investigating the combination of Pegasys with ribavirin."

About Hepatitis C
Hepatitis C, a blood-borne infectious disease of the liver, is a leading cause of cirrhosis and liver cancer and the number-one reason for liver transplants in the U.S. An estimated four million Americans are infected with the virus, with 35,000 to 180,000 new infections each year. In the United States, the Centers for Disease Control and Prevention estimate that hepatitis C is responsible for eight to ten thousand deaths per year and could increase to 38,000 by the year 2010, surpassing annual HIV/AIDS deaths.

Hepatitis C is a blood-borne virus transmitted through body fluids, primarily blood or blood products, and sharing needles. In many patients, the mode of transmission is unknown. Unfortunately, most people who are infected with hepatitis C are unaware of it because, like HIV, it may take years for symptoms to develop. In addition, it is estimated that as many as 40 percent of people with HIV may be co-infected with hepatitis C.

SOURCE: Doctor's Guide to Medical News <>

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