GSK's bepirovirsen receives US FDA Fast Track designation

GSK plc has received a Fast Track designation from the U.S. Food and Drug Administration (FDA) for bepirovirsen, an investigational drug candidate for the treatment of chronic hepatitis B (CHB). This designation is intended to expedite the development and review of drugs that treat serious conditions and address unmet medical needs.

Chronic hepatitis B affects nearly 300 million people worldwide, and current treatments offer a limited functional cure rate, often below 8%. Functional cure is defined as the undetectable levels of hepatitis B virus DNA and viral proteins, allowing the immune system to control the infection without medication. Existing oral antiviral therapies primarily suppress the virus rather than eliminating the surface antigen (HBsAg), which is considered essential for a functional cure.

Bepirovirsen is an antisense oligonucleotide (ASO) that has shown potential to achieve a clinically meaningful functional cure when used in combination with standard nucleoside/nucleotide analogue (NA) therapies. Data from the Phase IIb B-Clear and B-Sure trials supported the FDA application. The ongoing Phase III B-Well program is further evaluating the drug's efficacy and durability of response.

GSK highlighted that bepirovirsen is the only single agent in Phase III development with this potential. The B-Clear trial indicated that patients with lower baseline levels of HBsAg were more likely to benefit from bepirovirsen treatment. The drug was co-developed with Ionis Pharmaceuticals, and GSK in-licensed it in 2019. It is designed to target the virus's genetic material and potentially enable the immune system to regain control.