Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jan 7, 2016; 22(1): 349-360
Published online Jan 7, 2016. doi: 10.3748/wjg.v22.i1.349
Combination antiretroviral studies for patients with primary biliary cirrhosis
Ellina Lytvyak, Aldo J Montano-Loza, Andrew L Mason
Ellina Lytvyak, Aldo J Montano-Loza, Andrew L Mason, Division of Gastroenterology and Hepatology, University of Alberta, Edmonton T6G 2E1, Alberta, Canada
Author contributions: Both Lytvyak E and Mason AL wrote the manuscript; Lytvyak E analyzed and interpreted the data, edited the manuscript; Mason AL conceived the studies, contributed new analytic tools, analyzed and interpreted the data; all the authors contributed to this manuscript.
Supported by Research support from Alberta Innovates Health Solutions, Canadian Institutes for Health Research (to Mason AL, MOP 97798); and Canadian Liver Foundation relevant to this manuscript.
Conflict-of-interest statement: All authors have no conflict of interest to declare. Abbott and Gilead have provided antiviral therapy for patients with primary biliary cirrhosis participating in clinical trials.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Correspondence to: Andrew L Mason, MBBS, FRCPI, Professor of Medicine, Division of Gastroenterology and Hepatology, University of Alberta, 7-142 Katz Group Rexall Centre, Edmonton T6G 2E1, Alberta, Canada.
Telephone: +1-780-4928176 Fax: +1-780-4921655
Received: June 8, 2015
Peer-review started: June 10, 2015
First decision: July 14, 2015
Revised: August 12, 2015
Accepted: November 9, 2015
Article in press: November 9, 2015
Published online: January 7, 2016

Following the characterization of a human betaretrovirus in patients with primary biliary cirrhosis (PBC), pilot studies using antiretroviral therapy have been conducted as proof of principal to establish a link of virus with disease and with the eventual aim to find better adjunct therapies for patients unresponsive to ursodeoxycholic acid. In the first open label pilot study, the reverse transcriptase inhibitor lamivudine had little demonstrable biochemical or histological effect after 1 year. Whereas, lamivudine in combination with zidovudine was associated with a significant reduction in alkaline phosphatase as well as improvement in necroinflammatory score, cholangitis and ductopenia over a 12 mo period. A double blind, multi-center randomized controlled trial using lamivudine with zidovudine for 6 mo confirmed a significant reduction in alkaline phosphatase, ALT and AST in patients on antiviral therapy. However, none of the patients achieved the stringent endpoint criteria for normalization of alkaline phosphatase. Furthermore, some patients developed biochemical rebound consistent with drug resistance. A major fault of these studies has been the inability to measure the viral load in peripheral blood and therefore, provide a direct correlation between improvement of hepatic biochemistry and reduction in viral load. Nevertheless, viral mutants to lamivudine with zidovudine were later characterized in the NOD.c3c4 mouse model of PBC that has been used to test other antiretroviral regimens to betaretrovirus. The combination of tenofovir and emtricitabine reverse transcriptase inhibitors and the HIV protease inhibitor, lopinavir were found to abrogate cholangitis in the NOD.c3c4 mouse model and the same regimen normalized the liver tests in a PBC patient with HIV and human betaretrovirus infection. This combination antiretroviral therapy has now been used in a double blind randomized controlled crossover study for patients with PBC followed by an open label extension study. Only a third of the PBC patients were able to tolerate the lopinavir but those maintained on tenofovir, emtricitabine and lopinavir experienced sustained and clinically meaningful reduction in hepatic biochemistry. While we await the histological and virological evaluation, it is clear that better tolerated regimens of antiretroviral treatment will be required in future clinical trials.

Keywords: Primary biliary cirrhosis, Antiretroviral therapy, Human betaretrovirus, Randomized controlled trial, Endpoints for trials

Core tip: Early experience with antiretroviral therapy in primary biliary cirrhosis (PBC) patients strongly suggests that reverse transcriptase inhibitors alone lack efficacy to provide sustained and clinically meaningful biochemical responses. In contrast, combination antiretroviral therapy with human immunodeficiency virus protease inhibitors have been linked with robust and long-lived biochemical responses in PBC patients capable of tolerating the therapy. The use of digital droplet polymerase chain reaction has markedly improved the sensitivity of viral detection in peripheral blood and should enable studies to link reduction in viral load with improvements in hepatic biochemistry and histology.