The US Food and Drug Administration (FDA) has granted Fast Track designation for GSK’s bepirovirsen, an investigational antisense oligonucleotide (ASO) for the treatment of chronic hepatitis B (CHB). Fast track designation is intended to facilitate the development and expedite the review of drugs to treat serious conditions and fill an unmet medical need.
The designation was requested based on the potential for bepirovirsen to address an unmet medical need for CHB, a serious and life-threatening condition. Data from the phase IIb trials B-Clear and B-Sure, which evaluated the efficacy, safety and durability of response of bepirovirsen in people with CHB, were submitted in support of the application. A confirmatory phase III programme, B-Well, is ongoing.
CHB affects nearly 300 million people worldwide, and current treatment options offer a less than 2-8% functional cure rate which is not clinically meaningful. Functional cure occurs when the hepatitis B virus DNA and viral proteins are at levels low enough to be undetectable in the blood and can be controlled by the immune system without medication. Currently available oral antiviral therapies – called nucleoside/nucleotide analogues (NAs) – only suppress the virus and do not directly lower hepatitis B surface antigen (HBsAg), which is essential for functional cure.
Bepirovirsen is the only single agent in phase III development that has shown the potential to achieve clinically meaningful functional cure response when combined with oral nucleoside/nucleotide analogues (NAs). This was demonstrated by positive results in the B-Clear and B-Sure clinical trials. B-Clear identified that patients with low baseline hepatitis B surface antigen levels are most likely to benefit from treatment with bepirovirsen. Bepirovirsen is also being investigated as a potential backbone therapy in future sequential regimens to pursue functional cure in a broader population of patients with CHB.
