Arbutus Biopharma announces preliminary data from AB-729 trial

Arbutus Biopharma announced that preliminary data from its on-going Phase 2a clinical trial evaluating the safety, tolerability and antiviral activity of the combination of AB-729, the company’s lead RNAi therapeutic, and pegylated interferon alfa-2a, or IFN, in patients with chronic hepatitis B virus, or cHBV, was presented at the European Association for the Study of the Liver, or EASL, Congress. The preliminary data suggests that the addition of IFN to AB-729 treatment was generally well tolerated and appears to result in continued HBsAg declines in some patients. Forty-three virally suppressed, HBeAg negative cHBV patients were enrolled in the clinical trial and received a lead-in of AB-729 plus nucleos(t)ide analog therapy for 24 weeks followed by 12 or 24 weeks of IFN with or without additional AB-729 doses. The preliminary data showed the following: The mean HBsAg decline from baseline during the lead-in phase was 1.6 log10 at week 24 of treatment which is comparable to what was previously seen in other clinical trials with AB-729. HBsAg levels less than100 IU/mL were noted during the treatment period in 93% of the patients. Four patients have reached HBsAg below the lower limit of quantitation during IFN treatment, however, none of the patients have achieved sustained seroclearance to date. AB-729 treatment alone or in combination with IFN was generally well tolerated. There were no serious adverse events, or SAEs, discontinuations or AB-729 treatment discontinuations. IFN-related treatment emergent adverse events, or TEAEs, were consistent with the known safety profile. Five patients required IFN dose modifications due to laboratory abnormalities. The clinical trial remains ongoing with most patients still in the early IFN treatment period continuing to be followed for on-treatment responses. After completion of the IFN treatment period, patients are followed for an additional 24 weeks on NA therapy alone, then assessed for NA discontinuation. Three patients have been evaluated to stop NA treatment to date, with one meeting the protocol-defined criteria to stop NA treatment.