Direct-acting antivirals ability to clear intestinal HCV-RNA in liver transplant patients

1 INTRODUCTION

The hepatitis C virus (HCV) infects approximately 170 million people worldwide. Chronic HCV infection remains the leading indication for liver transplantation (LTx)^1-6 which is the only curative treatment when significant hepatic decompensation occurs.^7-9 However, if the patient is HCV-RNA positive at the time of transplantation, the graft is generally re-infected by HCV virions present in the blood or in extra-hepatic reservoir (ERs).^{9, 10} Although the liver is, in fact, the primary site of HCV replication, several reports have demonstrated that HCV is able to infect and replicate also in other body tissues.^11-16 The gastrointestinal tract has been considered a possible ER of HCV since viral RNA or proteins have been detected in intestinal cells and in stool samples.^{13, 16-18} Indeed, we recently demonstrated that gastrointestinal mucosa (GIM) can represent an ER for HCV: viral minus-strand RNA was found in the cells of GIM and HCV quasispecies detected in GIM resulted to be compartmentalized, in comparison with HCV present in the blood and similar to the quasispecies found in the re-infected liver after transplantation, suggesting that HCV produced in GIM could contribute to graft re-infection¹⁶.

Until recently the standard of care for chronic HCV was the treatment with pegylated/interferon + ribavirin (PEG-IFN-alpha/RBV).^19-23 The introduction in the clinical practice of new direct antiviral agents (DAAs) has improved the clinical condition of patients with chronic hepatitis allowing to achieve sustained virologic response (SVR) in more than 95% of cases.^{24, 25} It is unknown whether the ERs of HCV are affected by antiviral treatment or whether the disappearance of the viremia induces HCV clearance from the other body compartments. In this study, we addressed this issue taking advantage of the comparative evaluation of the effect of PEG-IFN-alpha/RBV and sofosbuvir + ribavirin (SOF/RBV) treatment on HCV-RNA clearance in GIM through the analysis of GIM biopsies taken from HCV-positive patients treated because of HCV infection recurrence after LTx.

2 MATERIALS AND METHODS

3 RESULTS

4 DISCUSSION

The standard treatment for chronic HCV, previously based on PEG-IFN-alpha/RBV,^19-23 has been replaced in the last few years by the introduction of the DAAs, which have greatly increased the SVR rate and shortened duration of therapy.^{24, 25} SVR after antiviral therapy is evaluated according to the clearance of HCV-RNA from serum, but it is unknown whether the HCV-ERs are equally cleared by the antiviral treatment. In this study, we analyzed a population of patients affected by HCV recurrence after LTx, treated both with PEG-IFN-alpha/RBV and with SOF/RBV. Particularly, we evaluated the effect of the different antiviral treatments on the clearance of HCV-RNA in the gastrointestinal tract because of the previous evidence that HCV produced in GIM could contribute to graft re-infection.¹⁶ SVR was observed in 66.6% of the patients after treatment with SOF/RBV and in 46.6% of those treated with PEG-IFN-alpha/RBV. Regarding the presence of HCV-RNA in GI biopsies, SOF/RBV treatment resulted to be able to clear HCV in 85.7% of cases, whereas PEG-IFN-alpha/RBV cleared GIM HCV-RNA only in 26.6% of the patients (P < .001). The evidence that 45.5% of patients treated with PEG-IFN-alpha/RBV showed persistence of HCV-RNA in the GI tract indicates the inability of the treatment to clear the intestinal reservoir of the virus that, together with other factors, could contribute to restore viremia and then induce non response to the therapy. Indeed, in case of SOF/RBV treatment all the patients who were GIM HCV-RNA positive did not respond to the treatment. On the opposite, 100% of the responders were characterized by a complete HCV-RNA clearance in GI tract. This might imply that elimination of both serum and GI reservoir of HCV is mandatory to achieve a sustained complete response to any anti-HCV antiviral therapy. Indeed, it must be pointed out that the small percentage of HCV-infected patients non-responding to DAA includes particularly patients with severe clinical status (liver cirrhosis, liver transplantation, renal impairment, etc), who might be characterized by different pharmacokinetics and pharmacodynamics of DAAs.²⁶ Moreover, the compartmentalized molecular evolution of HCV-RNA in GI reservoir ¹⁶ could cause the emergence of viral variants resistant to DAAs not detectable in the blood. Thus, according to these considerations, in order to pursuit HCV clearance the findings of our study draw attention to consider the effects of DAAs to non-hepatic reservoirs of the virus. Indeed, although the new DAA therapy is highly efficacious (>95% cure rate) still a number of patients are NR and the reasons of DAA failure remain partially unclear. Our study suggests that, in order to effectively clear HCV infection the antiviral therapy should achieve the clearance of HCV not only from the hepatic but also from non-hepatic reservoirs.

CONFLICTS OF INTEREST

The authors declare that there are no conflicts of interest.

AUTHORS' CONTRIBUTION

GP involved in conception and design of the work, biopsy sample collection, data analysis, data interpretation, and editing. GR involved in conception and design of the work, clinical data and sample collection, sample laboratory and data analysis, and drafting of the work. FB involved in sample laboratory analysis. GC involved in biopsy sample collection. FT involved in statistical data analysis. AG involved in analysis and interpretation of data, and editing and critically revising of the work for important intellectual content. RV-GV involved in critically revising of the work for important intellectual content. PGC involved in data analysis, editing, and critically revising of the work for important intellectual content. All authors reviewed and approved final version of the manuscript.