Brii Biosciences has announced topline end-of-treatment (EOT) results from its Phase 2b ENRICH and ENHANCE studies evaluating next-generation combination approaches for chronic hepatitis B virus (HBV) infection.

 

The data highlighted a clear difference between the two trial strategies: ENRICH demonstrated strong hepatitis B surface antigen (HBsAg) loss rates consistent with earlier findings, supporting the potential role of BRII-179 as an immune-priming therapy. 

 

Meanwhile, ENHANCE did not show an improvement over previously reported combination cohorts, prompting the company to prioritize the ENRICH approach for future development.

 

The ENRICH study evaluated a sequential treatment strategy in which patients received BRII-179 before treatment with elebsiran and PEG-IFNα. At EOT, the study reported HBsAg loss rates of 42.9% (42/98) and 40.0% (20/50) across two BRII-179 dosing schedules — five doses every three weeks and seven doses every two weeks, respectively.

 

The results closely matched findings from ENSURE Cohort 4, where patients who had previously received BRII-179 achieved an HBsAg loss rate of 41.9% (13/31). According to Brii Bio, the consistency across studies strengthens the evidence that BRII-179 may play a key role in activating immune responses needed for functional cure strategies.

 

The company said it has engaged with China’s Center for Drug Evaluation of the National Medical Products Administration and reached preliminary alignment regarding a potential registrational study for the ENRICH approach.

 

By contrast, the ENHANCE study, which tested a concurrent triple combination of BRII-179, elebsiran, and PEG-IFNα, failed to improve HBsAg loss rates compared with ENSURE Cohorts 2 and 3. ENHANCE recorded an HBsAg loss rate of 25.5% (25/98), compared with 29.7% (11/37) in the earlier cohorts.

 

However, the regimen still outperformed the PEG-IFNα control arm, which showed an HBsAg loss rate of 10.2% (5/49).

 

The ENHANCE Part A-2 study also explored whether adding BRII-179 and elebsiran during the first 24 weeks could shorten PEG-IFNα treatment. The approach produced an HBsAg loss rate of 22.5% (18/80), suggesting that a full PEG-IFNα treatment course may remain necessary to achieve the strongest curative outcomes.

 

"These initial EOT data provide important insights into the relative performance of the ENRICH and ENHANCE study designs,” said David Margolis, Chief Medical Officer of Brii Bio. 

 

“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.”