Does Race or Ethnicity Impact the Efficacy of DAAs for the Treatment of HCV?

Traditionally, patients infected with the hepatitis C virus (HCV) are treated with an interferon-based drug approach. This traditional approach has been show to elicit lower sustained virologic response (SVR) rates in black and Hispanic patients than in white patients. New direct-acting antiviral agents (DAAs) have been shown in clinical trails to be highly efficacious and safer than traditional therapy. As a consequence, it is important to assess if these DAAs will elicit the same gap in SVR rates as interferon-based therapy across different racial and ethnic groups.

In a new study published in the Journal of Hepatology, Dr. George Ioannou, MD, MS, and colleagues sought to elucidate the relationship between these DAAs and the race and ethnicity of HCV-infected patients.

For the study, the authors compared different drug regimens in different racial groups in the Veterans Affairs (VA) health care system. They utilized data from a pool of 21,095 HCV-infected patients with a large number of patients belonging to minority groups, including blacks and Hispanics. The data, which extended back to the year 1999, included prescriptions, patient visits, laboratory and diagnostic tests, as well as any issues with treatment. The SVR rate was quantified for patients and, using statistical methods, the authors were able to determine if a correlation existed between SVR rates and race/ethnicity.

The authors determined that across all of the races in the study, those patients without liver cirrhosis had higher SVR rates than patients with cirrhosis. The same trend was observed for patients with decompensated cirrhosis, with those without this complication achieving higher SVR rates. In addition, the authors found that blacks and Hispanics were slightly more likely to terminate treatment earlier than white patients.

Based on their results, the authors concluded that although DAAs led to high rates of SVR in the approximately 21,000 veterans in the study, after adjusting their data for differences in baseline characteristics among the different races, they determined that black and Hispanic patients with HCV were less likely than white patients to reach a sustained response. They determined that this difference in SVR rates was not due to early treatment termination. In addition, in patients with a genotype-1 infection, black patients were shown to have much lower SVR rates than white patients when treatment lasted 8 weeks, as opposed to 12 weeks.

Although Dr. Ioannou and his colleagues reported a gap in SVR rates between minorities and white patients, the gap is still much smaller than when interferon-based therapy is administered. The difference in the effectiveness of DAAs in bridging the race gap could be due to the lack of dependence of DAAs on the interleukin-28B gene. This particular gene shows some diversity in the population, with black patients having lower prevalence of a particular allelic form of the gene that has been shown to correlate to higher SVR rates.

In one specific drug regimen, which combines ledipasvir and sofosbuvir, the authors noted that black patients had a much lower SVR than white patients when treatment lasted 8 weeks instead of 12 weeks. As a consequence, the authors suggest that 8 weeks of treatment should be avoided in black patients, a recommendation in agreement with suggestions set by the American Association for the Study of Liver Diseases as well as the Infectious Diseases Society of America.

Overall, the authors showed that DAAs successfully allow patients with HCV to achieve a sustained response across all racial and ethnic groups in the study. However, although differences were detected between minority groups and white patients, the gap is smaller when compared to the traditional interferon approach.

Samar Mahmoud graduated from Drew University in 2011 with a BA in Biochemistry and Molecular Biology. After two years of working in industry as a Quality Control Technician for a blood bank, she went back to school and graduated from Montclair State University in 2016 with an MS in Pharmaceutical Biochemistry. She is currently pursuing her PhD in Molecular and Cellular Biology at the University of Massachusetts at Amherst.