Arbutus Biopharma presents data from two HBV assets

Arbutus Biopharma (ABUS) announced the presentation of five posters, including one late-breaker, highlighting imdusiran, its RNAi therapeutic and AB-101, its oral PD-L1 inhibitor, at the European Association for the Study of the Liver Congress 2025. In a late-breaker poster presentation, the following select key end-of-study data were reported from the Phase 2a clinical trial evaluating stable nucleoside analogue therapy throughout the treatment period with imdusiran for 24 weeks and either Barinthus Biotherapeutic’s T-cell stimulating immunotherapeutic VTP-300 without nivolumab or with low dose nivolumab or placebo: Three patients in Group C with the addition of nivolumab had HBsAg loss at the end of the treatment period and seroconverted. All 3 patients had baseline HBsAg less than1000 IU/mL. Twenty-five percent of Group C patients with baseline HBsAg less than1000 IU/mL who received nivolumab reached functional cure with an overall functional cure rate in Group C of 15.3%. Most patients treated with imdusiran maintained quantitative HBsAg levels that were consistently lower than pre-treatment HBsAg levels during the post-treatment follow-up period. Compared to placebo more patients treated with imdusiran and VTP-300 were able to remain off NA therapy even without achieving functional cure. Treatment with imdusiran, VTP-300 and lose dose nivolumab was well tolerated with no serious adverse events, deaths or early treatment discontinuations. In addition, there were no immune related adverse events, including thyroid abnormalities. Also at EASL, Arbutus presented posters with pre-clinical and clinical data on AB-101, including Part 3 data from its Phase 1a/1b clinical trial, AB-101-001. Data from the first cohort of cHBV patients in Part 3 showed that once daily dosing of 10mg of AB-101 for 28 days was well tolerated, with PD-L1 receptor occupancy similar to that observed in healthy volunteers who received multiple doses of AB-101 10mg once daily. Importantly, there were no immune related adverse events reported in healthy volunteers or patients thus far, and no evidence of liver dysfunction.