Arbutus Biopharma announces new data from IM-PROVE trial

Arbutus Biopharma announced new data from its Phase 2a clinical trial IM-PROVE I showing that imdusiran, the company’s RNAi therapeutic, and 24 weeks of pegylated interferon alfa-2a, or IFN, a standard-of-care immunomodulator, added to ongoing nucleos(t)ide analogue, or NA, therapy, reduced HBsAg levels and led to sustained HBsAg loss in some patients with cHBV during and after treatment. These data were presented in the Viral Hepatitis B and D: New therapies, unapproved therapies or strategies poster session, and will be featured during a poster tour on Thursday, June 6 at the European Association for the Study of the Liver, or EASL, Congress. Select key data from this Phase 2a clinical trial include: Some patients who received either 48 or 24 weeks of imdusiran and 24 weeks of IFN with their ongoing NA therapy achieved undetectable HBsAg at the end-of-treatment that was sustained 24 weeks after completing imdusiran and IFN treatment. All six patients with sustained HBsAg loss have seroconverted with high anti-HBsAg antibody levels and are being followed for maintenance of both undetectable levels of HBsAg and HBV DNA for 24 weeks while off all therapy to assess for a functional cure. Two of the six patients have reached 12 weeks off all therapy while maintaining both undetectable levels of HBsAg and HBV DNA. The remaining four patients are at various timepoints less than 12 weeks off therapy with undetectable levels of HBsAg and HBV DNA. A total of 21 patients from across the four treatment cohorts have discontinued all therapy and are in the follow-up period. One patient that received 12 weeks of IFN treatment with imdusiran and NA therapy has maintained undetectable levels of HBsAg and HBV DNA while off all therapy for six months, thereby achieving a functional cure. To confirm undetectable HBsAg measured by the trial assay, the Abbott HBsAg Next Qualitative assay, an ultrasensitive, research use only assay with a detection limit of 0.005 IU/mL, was utilized. The Next Assay confirmed HBsAg loss in six of the seven patients at EOT, and those six maintained HBsAg loss for 24 weeks after completing imdusiran and IFN treatment. These data from the IM-PROVE I trial suggest that the combination of imdusiran and 24 weeks of IFN was generally safe and well-tolerated. There were no serious adverse events, or SAEs, related to imdusiran or IFN, and no adverse events leading to discontinuation. The most common imdusiran-related treatment emergent adverse events were transient ALT elevations and injection site bruising. The IFN-related TEAEs were consistent with the known safety profile of IFN.