Arbutus Announces Decision to Discontinue Development of AB-506, an Oral Capsid Inhibitor for the Treatment of Chronic Hepatitis B

WARMINSTER, PA, USA I October 03, 2019 I Arbutus Biopharma Corporation (Nasdaq: ABUS), a Hepatitis B Virus (HBV) therapeutic solutions company, today announced its decision to discontinue the clinical development of AB-506, an oral capsid inhibitor. AB-506 was in a Phase 1a/1b clinical trial for the treatment of chronic hepatitis B (CHB).

William H. Collier, President and Chief Executive Officer of Arbutus, stated, “We have observed two cases of acute hepatitis in our Phase 1a 28-day clinical trial in healthy volunteers. Consequently, the clinical trial and further development of AB-506 have been stopped.”

“The two subjects are experiencing resolution of their acute hepatitis. We will continue to follow them and the other study participants, as safety is our highest priority at Arbutus,” said Gaston Picchio, Ph.D. Chief Development Officer of Arbutus. “We intend to present results from the AB-506 Phase 1a/1b clinical trial along with further details regarding the two cases of acute hepatitis at an appropriate scientific meeting later in 2019.”

Michael J. Sofia, Ph.D., Chief Scientific Officer of Arbutus, added, “While we are disappointed in these recent clinical findings, we have a number of oral follow-on capsid inhibitor compounds with distinct chemical scaffolds that we believe have the potential to contribute to the inhibition of HBV replication as part of a combination regimen. Our objective is to select one of several lead compounds for IND-enabling studies by December of this year.”

As a result of the decision to discontinue further development of AB-506, Arbutus no longer expects to initiate a combination study of AB-506 and AB-729 in the second half of 2020.

About AB-506

AB-506 is an oral HBV capsid inhibitor. HBV core protein assembles into a capsid structure, which is required for viral replication. The current standard-of-care therapy for HBV, primarily nucleoside analogues that work by stopping the viral polymerase, significantly reduce virus replication, but not completely. Capsid inhibitors inhibit replication by preventing the assembly of functional viral capsids and also by inhibiting the uncoating step of the viral life cycle thus reducing the formation of new covalently closed circular DNA ("cccDNA"), the viral reservoir which resides in the cell nucleus.

About AB-729

AB-729 is a RNA interference (RNAi) therapeutic targeted to hepatocytes using Arbutus’ novel covalently conjugated N-acetylgalactosamine (GalNAc) delivery technology that enables subcutaneous delivery with expected monthly dosing. AB-729 inhibits viral replication and reduces all HBV antigens, including hepatitis B surface antigen (HBsAg) in preclinical models. Reducing HBsAg is thought to be a key prerequisite to enable reawakening of a patient’s immune system to respond to the virus.

About Arbutus

Arbutus Biopharma Corporation is a publicly traded (Nasdaq: ABUS) biopharmaceutical company dedicated to discovering, developing and commercializing a cure for patients suffering from chronic Hepatitis B infection. Arbutus is developing multiple drug candidates, each of which have the potential to improve upon the standard of care and contribute to a curative combination regimen.  For more information, visit

SOURCE: Arbutus Biopharma

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