Elebsiran and PEG-IFNα for chronic hepatitis B infection: a partially randomized, open-label, phase 2 trial

Functional cure is a goal for the treatment of chronic hepatitis B virus (HBV) infection; however, it is infrequently achieved with currently approved treatments. Here we provide a randomized evaluation of the small interfering RNA elebsiran, in combination with pegylated interferon alfa (PEG-IFNα), compared with PEG-IFNα monotherapy. In addition, this study evaluates the potential role of the HBV therapeutic vaccine BRII-179 in identifying immunologically responsive patients and improving hepatitis B surface antigen (HBsAg) loss rates. In part I (cohorts 1-3), virally suppressed participants with chronic HBV infection naive to BRII-179 were randomized 1:1:1 to receive 48 weekly doses of PEG-IFNα alone or in combination with 13 doses of elebsiran (200 mg or 100 mg) administered every 4 weeks. In part II (cohort 4), participants who had previously received 9 doses of elebsiran and BRII-179 in a prospective study (BRII-179-835-001) were categorized as BRII-179 anti-HBs responders or nonresponders based on their peak hepatitis B surface antibody (anti-HBs) levels (≥10 IU l^-1 or <10 IU l^-1, respectively) and subsequently received 13 doses of elebsiran 100 mg every 4 weeks plus 48 weekly doses of PEG-IFNα. Primary endpoints were HBsAg loss at the end of treatment (EOT) and 24 weeks post-EOT. In part I, at 24 weeks post-EOT, HBsAg loss was observed in 4 out of 19 (21.1%) participants receiving elebsiran 200 mg plus PEG-IFNα, 6 out of 18 (33.3%) participants receiving elebsiran 100 mg plus PEG-IFNα and 1 out of 18 (5.6%) participants receiving PEG-IFNα monotherapy. In part II, HBsAg loss was observed in 9 out of 31 (29.0%) participants at 24 weeks post-EOT, with a higher response among BRII-179 anti-HBs responders (8 out of 19 participants, 42.1%) compared with nonresponders (1 out of 12 participants, 8.3%). Elebsiran and PEG-IFNα combination therapy was generally safe and well tolerated. These results demonstrate an additive benefit of elebsiran when combined with PEG-IFNα in achieving sustained HBsAg loss. Furthermore, the increased HBsAg loss rate in BRII-179 anti-HBs responders suggests that BRII-179 may be a valuable tool for immunological profiling to optimize curative outcomes in patients with HBV infection. ClinicalTrials.gov registration: NCT05970289 .