Benzinga | Jul 6, 2021 07:03AM EDT

Arbutus Biopharma And Vaccitech Announce Clinical Trial Collaboration Agreement To Evaluate RNAi Therapeutic, AB-729, In Combination With Immunotherapeutic, VTP-300, In Subjects With Chronic Hepatitis B Virus Infection

Arbutus Biopharma Corporation (NASDAQ:ABUS) and Vaccitech plc (NASDAQ:VACC) today announced that the companies have entered into a clinical trial collaboration agreement to evaluate an innovative therapeutic combination for the treatment of subjects with chronic hepatitis B virus (HBV) infection (CHB) who are already receiving standard-of-care nucleos(t)ide reverse transcriptase inhibitor (NrtI) therapy.



The multi-center, Phase 2a clinical trial will evaluate the safety, pharmacokinetics, immunogenicity, and antiviral activity of Arbutus's proprietary GalNAc delivered RNAi therapeutic, AB-729, followed by Vaccitech's proprietary immunotherapeutic, VTP-300, in NrtI-suppressed subjects with CHB. The Phase 2a clinical trial is expected to initiate in the second half of this year and will be managed by Arbutus, subject to oversight by a joint development committee comprised of representatives from Arbutus and Vaccitech. The parties retain full rights to their respective product candidates and will split all costs associated with the clinical trial. Pursuant to the agreement, the parties intend to undertake a larger Phase 2b clinical trial depending on the results of the initial Phase 2a clinical trial.

"Based on the positive clinical results we have seen in our ongoing Phase 1a/1b clinical trial for AB-729, including recent data demonstrating increased HBV-specific immune responses, we believe AB-729 has the potential to become a cornerstone therapeutic in multiple future HBV combination regimens," stated Gaston Picchio, Chief Development Officer at Arbutus. "We are looking forward to initiating this proof-of-concept Phase 2a clinical trial, which will allow us to evaluate the combination of two promising clinical candidates with potential complimentary mechanisms of action. We believe combining AB-729, which is designed to reduce HBsAg resulting in increased HBV immune responses with VTP-300, an immunotherapeutic designed to elicit an HBV specific immune response, may offer patients with CHB a much needed and durable functional cure."

"CHB is characterized by T cell exhaustion, driven primarily by HBsAg, that may require immune modulation," said Tom Evans, MD, Vaccitech's Chief Scientific Officer. "Current treatments can control viral replication but do not cure the disease. We believe that a combination of immunotherapy, such as VTP-300, with agents that reduce hepatitis B surface antigen is a promising approach toward a functional cure. This clinical trial will be evaluating that hypothesis. If successful, we believe that VTP-300, along with siRNA, such as AB-729, could be a foundation for CHB combination therapy."

About the Phase 2a Clinical Trial

Pending regulatory approval, the trial is expected to enroll 40 NrtI-suppressed, Hepatitis B e-antigen negative or positive, non-cirrhotic CHB subjects. Subjects are expected to receive AB-729 + NrtI for 24 weeks. At Week 24, subjects will be randomized 1:1 to receive either NrtI + VTP-300 or NrtI + VTP-300 sham. At Week 48, all subjects are expected to be evaluated for eligibility to either discontinue all treatments or remain on their NrtI only. Subjects are expected to be followed for an additional 48 weeks.