Antiviral drugs and the treatment of hepatitis C

German cohort of HCV mono-infected and HCV/HIV co-infected patients reveals relative under-treatment of co-infected patients

Background

Current German and European HIV guidelines recommend early evaluation of HCV treatment in all HIV/HCV co-infected patients. However, there are still considerable barriers to initiate HCV therapy in everyday clinical practice. This study evaluates baseline characteristics, “intention-to-treat” pattern and outcome of therapy of HCV/HIV co-infected patients in direct comparison to HCV mono-infected patients in a “real-life” setting.

Methods

A large, single-center cohort of 172 unselected HCV patients seen at the Infectious Diseases Unit at the University Medical Center Hamburg-Eppendorf from 2000–2011, 88 of whom HCV/HIV co-infected, was retrospectively analyzed by chart review with special focus on demographic, clinical and virologic aspects as well as treatment outcome.

Results

Antiviral HCV combination therapy with PEG-interferon plus weight-adapted ribavirin was initiated in 88/172 (52%) patients of the entire cohort and in n = 36 (40%) of all HCV/HIV co-infected patients (group A) compared to n = 52 (61%) of the HCV mono-infected group (group B) (p = 0.006). There were no significant differences of the demographics or severity of the liver disease between the two groups with the exception of slightly higher baseline viral loads in group A. A sustained virologic response (SVR) was observed in 50% (n = 18) of all treated HIV/HCV co-infected patients versus 52% (n = 27) of all treated HCV mono-infected patients (p = 0.859). Genotype 1 was the most frequent genotype in both groups (group A: n = 37, group B: n = 49) and the SVR rates for these patients were only slightly lower in the group of co-infected patients (group A: n = 33%, group B: 40% p = 0.626). During the course of treatment HCV/HIV co-infected patients received less ribavirin than mono-infected patients.

Conclusion

Overall, treatment was only initiated in half of the patients of the entire cohort and in an even smaller proportion of HCV/HIV co-infected patients despite comparable outcome (SVR) and similar baseline characteristics. In the light of newer treatment options, greater efforts to remove the barriers to treatment that still exist for a great proportion of patients especially with HIV/HCV co-infection have to be undertaken.

Sequence-specific alterations of epitope production by HIV protease inhibitors

Ag processing by intracellular proteases and peptidases and epitope presentation are critical for recognition of pathogen-infected cells by CD8+ T lymphocytes. First-generation HIV protease inhibitors (PIs) alter proteasome activity, but the effect of first- or second-generation PIs on other cellular peptidases, the underlying mechanism, and impact on Ag processing and epitope presentation to CTL are still unknown. In this article, we demonstrate that several HIV PIs altered not only proteasome but also aminopeptidase activities in PBMCs. Using an in vitro degradation assay involving PBMC cytosolic extracts, we showed that PIs altered the degradation patterns of oligopeptides and peptide production in a sequence-specific manner, enhancing the cleavage of certain residues and reducing others. PIs affected the sensitivity of peptides to intracellular degradation, and altered the kinetics and amount of HIV epitopes produced intracellularly. Accordingly, the endogenous degradation of incoming virions in the presence of PIs led to variations in CTL-mediated killing of HIV-infected cells. By altering host protease activities and the degradation patterns of proteins in a sequence-specific manner, HIV PIs may diversify peptides available for MHC class I presentation to CTL, alter the patterns of CTL responses, and provide a complementary approach to current therapies for the CTL-mediated clearance of abnormal cells in infection, cancer, or other immune disease.