HCV Reinfection and Injection Risk Behavior Following Elbasvir/Grazoprevir Treatment in Participants on Opioid Agonist Therapy: Co-Star Three-Year Follow-Up Study

Author: Grebely J, Altice F, Litwin AH, Dalgard O, Gane E, Shibolet O, Luetkemeyer A, Nahass R, Peng C-Y, Conway B, Iser DM, Huang H-C, Gendrano IN, Kelly M, Hwang P, Robertson M, Wahl J, Barr E, Platt HL, Dore GJ

Theme: Clinical Research Year: 2017

Background/Aim: High rates of efficacy were observed in Co-STAR, a 12-week, phase 3 trial of elbasvir/grazoprevir (EBR/GZR; an NS5A inhibitor and an NS3/4A protease inhibitor) in participants on opioid agonist therapy (OAT). The aim of the Co-STAR Three Year Follow-up Study (3YFU) is to evaluate hepatitis C virus (HCV) reinfection and injection risk behaviors in participants treated with EBR/GZR.

Methods: This 3-year observational cohort study enrolled participants who received ≥1 dose of EBR/GZR in the phase 3 trial. Every 6 months, participants are tested for HCV RNA, and if detected, viral genotype and sequencing are performed. Participants completed a questionnaire to assess drug use.

Results: Of 296 participants treated in Co-STAR, 199 (67%) were enrolled in the 3YFU (76% male; 79% white; 8% HIV/HCV co-infection; 80% receiving methadone). Participants enrolled in the 3YFU were older than those not enrolled (average age, 49 vs 44 years), and fewer were infected with genotype 1a (72% vs 84%) or had a positive urine drug screen at enrollment (56% vs 68%). Of the 191 participants in 3YFU for whom injection risk behavior information was available, 42% (n=81) reported noninjection drug use and 25% (n=48) reported injection drug use in the last 6 months. Among 296 participants treated in Co-STAR, 8 cases of HCV reinfection were observed over 198 person-years of follow-up (4.0/100 person-years; 95% confidence interval 1.7-8.0). Spontaneous clearance was seen in 3 of 5 reinfections detected through follow-up week (FW)12 and in none of 3 reinfections detected after FW12.

Conclusion: The rate of HCV reinfection following EBR/GZR treatment among those receiving OAT was consistent with rates from previous meta-analyses of studies in persons who use drugs. Further analyses will evaluate the impact of ongoing drug use on HCV reinfection risk and the incidence of HCV reinfection up to 3 years’ post-EBR/GZR treatment.

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