Arbutus announces preliminary EOT data from Phase 2a trial of imdusiran, VTP-300

Arbutus Biopharma Corporation (ABUS) announced new preliminary end-of-treatment data from the Phase 2a clinical trialin patients receiving ongoing standard-of-care nucleos(t)ide analogue therapy indicating that treatment with imdusiran, Arbutus’ RNAi therapeutic, followed by Barinthus Biotherapeutic’s (BRNS) T-cell stimulating immunotherapeutic, VTP-300, was generally safe, well-tolerated and led to maintenance of lower HBsAg levels during the post-treatment follow-up period in patients with cHBV. The data were presented today by Dr. Kosh Agarwal, MD, Consultant Hepatologist and Transplant Physician at the Institute of Liver Studies at King’s College Hospital, London, during a session focused on new treatments for viral hepatitis B at the European Association for the Study of the Liver Congress. Dr. Agarwal presented the following data from 38 of 40 patients that were on stable NA therapy throughout the treatment period, received imdusiran for 24 weeks and were then randomized to receive either VTP-300 or placebo at Weeks 26 and 30: Robust reductions of HBsAg were seen during the imdusiran lead-in period with 95% of patients achieving HBsAg less than100 IU/mL before undergoing dosing in the treatment or placebo arm. At 24-weeks post-EOT, there was a significant difference in HBsAg levels between the treatment arm and placebo. 94% of patients in the treatment arm achieved HBsAg levels of less than100 IU/mL and 36% had less than10 IU/mL at EOT compared to 84% and 21%, respectively in the placebo arm. Similarly, at 24-weeks post-EOT, the treatment arm had lower HBsAg levels with 80% of patients at less than100 IU/mL and 60% at less than10 IU/mL compared to the placebo arm with 16% and 0%, respectively. 84% of patients in the treatment arm met the NA therapy discontinuation criteria and stopped NA treatment after Week 48 compared to 53% in the placebo arm. One patient in the treatment arm achieved undetectable HBsAg and another had a greater than1.5 log10 decline between the last two visits during the NA-therapy discontinuation follow-up period. Treatment with imdusiran and VTP-300 was generally safe and well-tolerated. There were no Serious Adverse Events, Grade 3 or 4 Adverse Events or discontinuations due to treatment. The most common treatment-related AEs in two or more patients were injection site-related and transient ALT increases.