GSK hails 'unprecedented' cure rates with hep B drug
GSK's antisense-based drug for chronic hepatitis B (CHB), bepirovirsen, can achieve a functional cure in 19% of patients, according to a new analysis of data from the pivotal B-Well 1 and B-Well-2 trials.
The data presented at the European Association for the Study of the Liver (EASL) congress, and simultaneously published in the New England Journal of Medicine, build the evidence base for bepirovirsen as GSK works towards an FDA verdict on its marketing application for the drug in October.
The 19% functional cure response rate – which means the virus is no longer able to replicate at detectable levels – was achieved with a six-month bepirovirsen treatment course, and compared to a 0% rate in the control group taking placebo.
In addition, around a quarter (26%) of a subgroup of patients with a lower viral load at baseline achieved a functional cure, while nearly half (49%) of all bepirovirsen-treated subjects saw levels of hepatitis B surface antigen (HBsAg) fall below the detectable limit of 100 IU/mL after 12 months.
The studies, which include time on and off background therapy with daily oral antivirals, raise the prospect of CHB becoming treatable without lifelong therapy, according to GSK.
"Today's standard of care for CHB imposes a heavy burden on patients and healthcare systems, and rarely delivers a functional cure," commented Prof Jinlin Hou of Guangdong Institute of Hepatology in China, who is the lead author of the NEJM paper.
"Combined with improved testing and diagnosis, this innovation has the potential to improve the lives of millions living with CHB," he added.
Around 250 million people around the world live with CHB, and standard treatment with antivirals and pegylated interferons can usually only deliver a functional cure in 1% to 4% of cases. A functional cure is particularly important, as it dramatically reduces the risk of long-term liver complications, including liver cancer, as well as all-cause mortality.
The B-Well trial results, described as a "major step towards a cure for hepatitis B infection" in an editorial accompanying the NEJM study, are also an important part of GSK's growth plans, which include hitting a target of driving annual revenues above £40 billion ($54 billion) by 2031.
The company is modelling peak sales of bepirovirsen at around £2 billion a year. Along with the FDA filing, the drug has also been submitted for approval in Europe, Japan, and China, and GSK has said it is preparing for launch after regulatory approvals in the third quarter.
