GSK drug achieves 19% functional cure rate for hepatitis B

GSK’s Bepirovirsen Achieves 19% Functional Cure Rate for Chronic Hepatitis B in Landmark Phase 3 Trials

GSK and Ionis Pharmaceuticals announced that bepirovirsen, an investigational antisense oligonucleotide, achieved a 19% functional cure rate in two pivotal Phase 3 trials enrolling over 1,800 patients with chronic hepatitis B — compared to 0% in those receiving standard of care alone. The results, published simultaneously in the New England Journal of Medicine and presented at the European Association for the Study of the Liver congress, mark the first time a drug has demonstrated clinically meaningful functional cure rates in the disease.morningstar

Trial Results

Pooled data from the B-Well 1 and B-Well 2 trials showed that 233 of 1,220 patients treated with bepirovirsen for six months achieved functional cure — defined as undetectable hepatitis B surface antigen and viral DNA for at least 24 weeks after stopping all treatment — versus none of 614 patients on placebo (p<0.001 in both trials). Among participants with lower baseline surface antigen levels (≤1,000 IU/mL), which represents roughly 45% of diagnosed cases globally, the functional cure rate reached 26%.lasvegassun

In an exploratory analysis, 49% of bepirovirsen recipients achieved surface antigen levels of ≤100 IU/mL one year after the end of treatment, a threshold linked in medical literature to improved immune control and reduced risk of liver cancer. Bepirovirsen demonstrated an acceptable safety profile consistent with earlier studies.morningstar

Regulatory Path

The FDA accepted bepirovirsen for priority review in April and granted it Breakthrough Therapy Designation, building on a Fast Track Designation received in February 2024. The agency assigned October 26, 2026, as the PDUFA goal date. China’s National Medical Products Administration has also accepted the filing for priority review. If approved, bepirovirsen would become the first finite, six-month therapeutic option for chronic hepatitis B, a disease affecting more than 250 million people worldwide where current nucleoside analogue therapy typically requires lifelong use and achieves functional cure in less than 1% of patients.gsk

Broader Implications

GSK’s Chief Scientific Officer Tony Wood called bepirovirsen “a first for the disease” in its potential to transform treatment goals. The company is also developing bepirovirsen as a backbone for future sequential treatment strategies aimed at expanding functional cure to broader patient populations. The drug was licensed from Ionis Pharmaceuticals, and the two companies collaborated on its development.gsk