VIR-2218 (elebsiran) plus pegylated interferon-alfa-2a in participants with chronic hepatitis B virus infection: a phase 2 study.

Background: Chronic hepatitis B virus (HBV) remains a global concern, with current treatments achieving low rates of HBsAg seroclearance. VIR-2218 (elebsiran), a small interfering RNA agent against HBV transcripts, reduces HBsAg concentrations. We aimed to evaluate the safety and antiviral activity of VIR-2218 with and without pegylated interferon-alpha-2a treatment in participants with chronic HBV.

Methods: This open-label, phase 2 study was conducted at 23 sites in six countries (New Zealand, Australia, Hong Kong, Thailand, South Korea, and Malaysia). Adults (aged 18-65 years) with chronic HBV infection without cirrhosis and with HBsAg more than 50 IU/mL and HBV DNA less than 90 IU/mL who were on continued nucleoside or nucleotide reverse transcriptase inhibitor (NRTI) therapy for 2 months or longer were eligible. Participants were enrolled into one of six cohorts to receive VIR-2218 200 mg subcutaneously every 4 weeks, with or without 180 μg subcutaneous pegylated interferon-alfa-2a once per week. Cohort 1 received six doses of VIR-2218 (total 20 weeks); cohort 2 received six doses of VIR-2218 starting at day 1, plus 12 doses of pegylated interferon-alfa-2a starting at week 12 (total 24 weeks); cohort 3 received six doses of VIR-2218 and 24 doses of pegylated interferon-alfa-2a (total 24 weeks); cohort 4 received six doses of VIR-2218 and up to 48 doses of pegylated interferon-alfa-2a (total 48 weeks); cohort 5 received up to 13 doses of VIR-2218 and up to 44 doses of pegylated interferon-alfa-2a (total 48 weeks); and cohort 6 received three doses of VIR-2218 and 12 doses of pegylated interferon-alfa-2a (total 12 weeks). The primary endpoints were the incidence of adverse events and clinical assessments (including results of laboratory tests). Secondary endpoints were the mean maximum reduction of serum HBsAg at any timepoint; the proportion of participants with serum HBsAg seroclearance at any timepoint and for more than 6 months after the end of treatment; and the proportion of participants with anti-HBs seroconversion at any timepoint. For patients who were HBeAg-positive, we also assessed the proportion with HBeAg seroclearance or anti-HBe seroconversion at any timepoint. This study is registered with ClinicalTrials.gov, NCT03672188, and is ongoing.

Findings: Between July 2, 2020, and Nov 2, 2021, 124 individuals were screened for eligibility, 84 of whom were enrolled (15 in cohort 1, 15 in cohort 2, 18 in cohort 3, 18 in cohort 4, 13 in cohort 5, and five in cohort 6). Participants were predominantly HBeAg-negative, Asian, and male (66 [79%] participants were male and 18 [21%] were female). Most treatment emergent adverse events were grades 1-2. Three (20%) participants in cohort 1, four (27%) in cohort 2, eight (44%) in cohort 3, seven (39%) in cohort 4, six (46%) in cohort 5, and two (40%) in cohort 6 reported treatment-emergent adverse events related to VIR-2218. 12 (80%) participants in cohort 2, 12 (67%) in cohort 3, 14 (78%) in cohort 4, 13 (100%) in cohort 5, and three (60%) in cohort 6 reported treatment-emergent adverse events related to pegylated interferon-alfa-2a. Two (13%) participants in cohort 1 had elevations in alanine aminotransferase, compared with 13 (87%) participants in cohort 2, 15 (83%) in cohort 3, 17 (94%) in cohort 4, 11 (85%) in cohort 5, and three (60%) in cohort 6. The mean maximum change from baseline at any timepoint in HBsAg concentration was -2·0 log IU/mL (95% CI -2·1 to -1·8) in cohort 1, -2·2 log IU/mL (-2·5 to -1·8) in cohort 2, -2·5 log IU/mL (-2·8 to -2·1) in cohort 3, -2·4 log IU/mL (-3·1 to -1·8) in cohort 4, -3·0 log IU/mL (-3·7 to -2·3) in cohort 5, and -1·7 log IU/mL (-2·1 to -1·4) in cohort 6. 11 participants (one in cohort 2, one in cohort 3, five in cohort 4, and four in cohort 5) receiving VIR-2218 plus pegylated interferon-alfa-2a had HBsAg seroclearance at any timepoint. Of these, ten (91%; one in cohort 2, five in cohort 4, and four in cohort 5) had anti-HBs seropositivity. Six participants (one in cohort 2, three in cohort 4, and two in cohort 5) had sustained HBsAg seroclearance through to 24 weeks after the end of treatment. No participants receiving VIR-2218 monotherapy (cohort 1) or VIR-2218 plus pegylated interferon-alfa-2a 12-week regimen (cohort 6) had HBsAg seroclearance. 12 (42%) of 26 participants (one of four in cohort 1, two of six in cohort 2, four of seven in cohort 3, four of six in cohort 4, and one of three in cohort 5) who were HBeAg positive at baseline had HBeAg seroclearance or anti-HBe seroconversion.

Interpretation: The results of this phase 2 study support further development of VIR-2218 as a potential therapy for patients with chronic HBV infection. Additional clinical trials of VIR-2218 with and without pegylated interferon-alfa-2a in combination with an HBsAg-targeting monoclonal antibody are ongoing.

Funding: Vir Biotechnology.