Results of a new study published in the current issue of the New England Journal of Medicine show that in patients who have chronic
hepatitis C, genotype 1 -- the most common form of the disease and difficult to treat successfully -- non-Hispanic whites achieved one of the highest response rates reported to date, but response rates in African Americans were significantly lower. The findings challenge much of the current thinking about why African Americans respond less well to hepatitis C treatment and underscore the need for further clinical research.
In the large open-label study, non-Hispanic white patients achieved a sustained virologic response (SVR) rate of 52 percent, which was significantly higher than the 19 percent seen in African American patients (p < 0.001). SVR is the sustained undetectability of the hepatitis C virus for six months following therapy. Lower SVR rates in African Americans, as seen in this study, also have been seen in past studies using other forms of interferon therapy, including the newer peginterferon and ribavirin combination therapies.
"The sustained virologic response rates achieved in this study in genotype 1 patients demonstrate that peginterferon alfa-2b and ribavirin combination therapy is effective," said lead investigator Andrew Muir, M.D., assistant professor of medicine, Division of Gastroenterology, Duke University Medical Center, Durham, North Carolina. He noted that the study was conducted in a "real-world" community setting, rather than in a more restrictive clinical trial. "However, the lower response rate in African Americans poses a critical challenge because even with the best therapies currently available, African American patients clearly have a lower response rate."
In the study, 100 African American and 100 non-Hispanic white patients with chronic hepatitis C, genotype 1, were treated with a regimen of peginterferon alfa-2b (1.5 mcg/kg/weekly) and 1,000 mg of ribavirin daily for the first 12 weeks and then 800 mg daily thereafter, for a total of 48 weeks. Growth factors were not used. The current U.S. label for peginterferon alfa- 2b (1.5 mcg/kg/week) recommends that it be used in combination with 800 mg of ribavirin daily. The investigators analyzed a number of variables, including patients' socio-demographic and clinical characteristics, and found that only race was significantly associated with the difference in SVR rates.
The study demonstrated the safety and tolerability of peginterferon alfa- 2b and ribavirin combination therapy in these patients, and showed that the rates and types of adverse events were similar in the African American and non-Hispanic white patient groups. Importantly, the rate of dose reduction of peginterferon alfa-2b because of neutropenia was similar in the two groups (13 vs. 14 percent, respectively) as was the rate of discontinuation due to neutropenia (4 vs. 3 percent, respectively). Neutropenia often is a concern when treating African Americans, as seen in previous clinical studies.
Challenging Current Thinking
Dr. Muir said the reasons for the different responses seen in the racial groups remains unknown, but the study results counter at least some previously held hypotheses. For example, some suggested the disparity could be due to a higher prevalence of hepatitis C, genotype 1, in African Americans, but in this study 98 percent of both racial groups had that form of the virus. Further analyses showed that other variables -- including age, sex, education, body weight, initial viral load, duration of HCV infection and other clinical factors -- had no significant effect on response. "Showing these other factors are not the reason for the difference in response rates adds to our understanding of the disease and is important in furthering research to identify what factors actually are responsible. We can speculate about what those causes might be, but we need additional clinical studies to get real answers," he said.
Importance of Treatment
"While we are concerned about these findings in African Americans, it is critical to point out that many of these patients do, in fact, respond to hepatitis C treatment, so it is vitally important for an infected individual to aggressively pursue, with their physician, evaluation for therapy," urged Jonathan McCone, M.D., director, Mount Vernon Endoscopy Center in Alexandria, Va., and a participating investigator in the study. He noted that hepatitis C, the most common blood-borne infection in America, affects approximately 4 million people, including a disproportionately high percentage of African Americans. Chronic hepatitis C infection substantially increases the risk of cirrhosis and liver cancer, and is the most frequent indication for liver transplantation among adults. "Timely therapy can help achieve a sustained virologic response," McCone said, "and patients can improve their chances of achieving an SVR by adhering to therapy."
Dr. Muir concurred, noting that the study found a higher SVR rate (23 percent) among African Americans who completed the full course of therapy.
A Patient's Perspective
The importance of adhering to treatment is exemplified by Jackie Boykin, R.N., 41, an African American woman who contracted hepatitis C in the course of her work as a nurse. While not a participant in the study by Muir and his colleagues, she was treated at Duke University Medical Center. In 2002, Boykin received combination therapy with PEG-INTRON(R) (peginterferon alfa-2b) Powder for Injection and REBETOL(R) (ribavirin, USP) Capsules. She achieved an SVR and has been virus free for nearly one-and-a-half years. As a result of her experience, Boykin counsels many patients with hepatitis C to stay with the therapy "because compliance is so important to treating the disease," she said.
"I found the Schering-Plough PEG-INTRON Web site very helpful, and the support I received from the nurses in the Be In Charge program helped me stay on therapy." Schering-Plough's Be In Charge hepatitis C patient-support program provides educational materials and telephone contact with registered nurse counselors skilled in the management of hepatitis C. "Support from family, the community and medical professionals is critical for hepatitis C patients," Boykin said. She continues to attend a hepatitis C patient support group at Duke University Medical Center.
Commitment to Hepatitis C Research