Brii Biosciences (Brii Bio) has reported topline end-of-treatment (EOT) data from its ongoing Phase IIb ENRICH and ENHANCE trials assessing sequential and concurrent use of BRII-179, elebsiran, and PEG-IFNα to treat chronic hepatitis B virus (HBV) infection.
These studies aim to define the optimal combination regimen and BRII-179’s potential as part of a functional cure approach.
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The ENRICH study examined BRII-179 as a priming therapy administered before elebsiran and PEG-IFNα.
Patients who received BRII-179 followed by these therapies showed hepatitis B surface antigen (HBsAg) loss rates of 42.9% (42 of 98) with five doses (every three weeks) and 40% (20 of 50) with seven doses (every two weeks).
These outcomes align with previous ENSURE Cohort 4 data, supporting the immune priming effect of BRII-179.
Brii Bio has engaged with China’s Center for Drug Evaluation of the National Medical Products Administration (NMPA), reaching preliminary alignment for a potential registrational trial.
In the ENHANCE (Part A-1) study, a concurrent triple combination regimen yielded an HBsAg loss rate of 25.5% (25 of 98), which did not surpass rates observed in previous ENSURE Cohorts 2 and 3 at 29.7% (11 of 37). However, it was higher than the control arm using PEG-IFNα alone, at 10.2% (5 of 49).
Subgroup analyses suggest that BRII-179 may trigger beneficial immune responses regardless of patients’ baseline HBsAg levels, particularly among those with higher initial readings (1,000IU/mL-3,000IU/mL), consistent with previous findings.
The ENHANCE Part A-2 study evaluated a sequential therapy approach, with BRII-179 plus elebsiran during the first 24 weeks, followed by elebsiran and PEG-IFNα for another 24 weeks.
This regimen resulted in an HBsAg loss rate of 22.5% (18 of 80), suggesting a full course of PEG-IFNα is required for optimal efficacy.
HBsAg loss remains a key endpoint but requires post-treatment follow-up to confirm durability. No new safety issues were detected.
Brii Bio chief medical officer Dr David Margolis said: “These initial EOT data provide important insights into the relative performance of the ENRICH and ENHANCE study designs.
“While longer-term follow-up is needed to assess durability of the HBsAg loss, the data observed to date, together with EOT and post-EOT findings from multiple prior studies, are very consistent, suggesting that the ENRICH study design is preferred for a registrational study. We look forward to sharing the more complete dataset later this year.”
