Arbutus Biopharma Corp. is postponing an early stage study evaluating its hepatitis B drug AB-452 due to nonclinical safety findings.

Hepatitis B is a potentially life-threatening liver infection caused by the hepatitis B virus, a small DNA virus that replicates through the infected person's RNA. According to the Centers for Disease Control and Prevention, about 257 million people have chronic hepatitis B worldwide.

Arbutus Biopharma's AB-452 is designed to block the replication of the virus by destabilizing or decreasing the stability of the virus' RNA. The drug is intended to be used in a combination regimen to treat chronic hepatitis B.

The phase 1 trial was initially scheduled to begin in the fourth quarter; however, the company noted that it needs more time to characterize AB-452 and expects to start the study after the ongoing nonclinical studies are completed.

Arbutus Biopharma's shares were down 26.67% to $4.40 as of 1:27 p.m. ET after the announcement.

In other news, the company appointed Gaston Picchio as chief development officer.

Picchio is joining the company from Johnson & Johnson's Janssen Biotech Inc. unit where he held various roles, including vice president of scientific innovation of infectious diseases and vaccines. He also served as the hepatitis disease area leader and vice president of clinical virology infectious diseases and vaccines in Janssen.

Burnaby, British Columbia-based Arbutus Biopharma develops and commercializes treatments for chronic hepatitis B infection.