2.1. Study Population
Adult patients with chronic HCV (CHC) infection treated with OBV/PTV/r + DSV ± RBV at Vilnius university hospital Santaros Klinikos centre of hepatology, gastroenterology and dietetics, centre of infectious diseases (Vilnius, Lithuania) and Riga East university hospital, infectology centre of Latvia, hepatology department (Riga, Latvia) from January 2015 to November 2016 were enrolled into the current study. Patients were eligible for OBV/PTV/r + DSV ± RBV treatment if infected with HCV GT1a, 1b, or 1a/b, were treatment-naïve or previously treated with PegINF/RBV ± first generation protease inhibitor telaprevir or boceprevir, and/or had advanced fibrosis (METAVIR stage F3 - F4). Eligible patients also included the ones with post-orthotopic liver transplantation and patients with F2 fibrosis stage with contraindications to interferon-based therapy or not tolerate to PegINF/RBV regimen. Patients with advanced liver decompensation and Child-Pugh C cirrhosis were excluded from the study.
2.2. Study Design
It was an international multicentre open-label, uncontrolled, real-world retrospective study conducted in Lithuania (2 centres) and Latvia (1 centre). The local hospitals ethics committees in each country approved the study.
The treatment of the OBV/PTV/r + DSV ± RBV for the part of patients was obtained within an early access patient program from January 2015 and written informed consent was obtained from each participitant. The therapy for the remaining patients was 100% reimbursed in October 29, 2015 in Lithuania and January 1, 2016 in Latvia.
Clinical assessments, concomitant treatments and other medical decisions were taken at the discretion of the treating physicians according to standard clinical practice. In accordance to the approved summaries of product characteristics, patients received a combination of OBV/PTV/r (25 mg, 150 mg, and 100 mg daily) and DSV (250 mg daily) with or without weight-based RBV (1000 - 1200 mg daily) for 12 or 24 weeks. Patients infected with GT1a were treated with OBV/PTV/r + DSV + RBV for 12 weeks (the ones without cirrhosis) or for 24 weeks (the ones with compensated cirrhosis and all patients undergone liver transplantation). All patients with GT1b-infection were treated with OBV/PTV/r + DSV ± RBV for 12 weeks. The dose of RBV was adjusted during the course of treatment according to laboratory test results and tolerability. In liver transplant recipients, the doses of immunosuppressive agents (tacrolimus and cyclosporine) were reduced according to plasma concentrations.
Patients data were collected retrospectively by reviewing individual’s health record. Baseline demographic and clinical data included gender, age, body mass index (BMI), fibrosis stage (METAVIR scoring system), HCV genotype, previous antiviral treatment, and response to previous treatments. Fibrosis was evaluated by liver biopsy and/or transient elastography (FibroScan). The Child-Pugh score system was used to define clinical status.
Laboratory parameters and adverse events (AE) were assessed at the baseline (the day 0), the weeks 1, 2, 4, 8, at the end of treatment (EOT, week 12 or 24), and at the follow-up (FU, 12 weeks after EOT), or until the premature discontinuation of treatment. Laboratory data included HCV ribonucleic acid (RNA) level, alpha-fetoprotein (AFP), international normalised ratio (INR), albumins, bilirubin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyltransferase (GGT), serum creatinine, platelets count (PLT), haemoglobin (Hb). HCV-RNA level was measured using real-time polymerase chain reaction (real-time PCR) according to standard methods at the baseline, at the EOT, and at FU visit.
At each visit, patients were interviewed to identify any adverse event.
2.3. Virologic and Safety Assessment
The primary effectiveness endpoint was SVR12, following the end of treatment. The secondary endpoints included end-of-treatment response (undetectable HCV RNA at the end of treatment), virologic relapse (undetectable HCV RNA at the end of treatment, but positive within 12 weeks post treatment), and non-response (HCV RNA being detectable at the end of treatment).
Safety endpoints included adverse events (AE) and laboratory abnormalities.
2.4. Serological and Molecular Diagnosis of Viral Spread
In the first step, to evaluate the exposure rate the presence of total anti-HCV antibodies was determined using 4th generation anti-HCV enzyme-linked immunosorbent assay (ELISA) kit on serum samples according to the manufacturer’s instructions.
Then, to investigate the current molecular state in cases with positive HCV antibody, viral RNA genome was extracted from sera by a commercially available kit. In addition, for more accurate evaluation, a commercial real-time PCR detection method was employed to confirm the presence of viral genome inside the serum. Finally, a simple genotyping assay was performed on family members with PCR positive results (
21).