The US Food and Drug Administration (FDA) has granted fast track designation to GSK’s bepirovirsen, an investigational treatment for chronic hepatitis B (CHB).

A triple-action antisense oligonucleotide (ASO), bepirovirsen is being analysed in a Phase III B-Well clinical trial programme.

It acts on and degrades the genetic components of the hepatitis B virus (HBV), enabling the immune system to combat the virus more effectively.

Bepirovirsen works by inhibiting viral DNA replication, suppressing hepatitis B surface antigen (HBsAg) levels and stimulating immune response.

The fast track status was supported by data from Phase IIb trials, B-Clear and B-Sure, which assessed the safety, efficacy and response durability of bepirovirsen in individuals with CHB.

The B-Clear trial included two cohorts, one consisting of subjects on nucleoside/nucleotide analogues (NAs) treatment and the other of participants not on NAs.

B-Sure is a follow-up study extending 33 months beyond B-Clear, to determine the lasting efficacy and response durability, including the potential for a functional cure in people who stop all medications and show no signs of HBsAg or HBV DNA.

Bepirovirsen is the only monotherapy in Phase III development stage that has demonstrated the potential to attain a clinically meaningful functional cure along with oral NAs, as evidenced by the positive outcomes from the B-Clear and B-Sure trials.

It is being explored as a foundational therapy in future sequential treatment regimens aimed at achieving a functional cure in a wider patient population with CHB.

Discovered and co-developed by GSK and Ionis Pharmaceuticals, bepirovirsen is among the ASO HBV programme assets in-licensed by GSK from Ionis Pharmaceuticals in August 2019.

Last month, GSK agreed to acquire asthma drug specialist Aiolos Bio in a $1.4bn deal as it aims to strengthen its respiratory and inflammatory asset pipeline.