Biopharmaceutical company GSK plc (LSE: GSK) (NYSE: GSK) announced on Monday that China's National Medical Products Administration has accepted for review a new drug application for bepirovirsen, an investigational antisense oligonucleotide, for the treatment of adults with chronic hepatitis B.

The submission is supported by positive Phase III data from the B-Well 1 and B-Well 2 trials, which demonstrated statistically significant and clinically meaningful functional cure rates when bepirovirsen was used alongside standard of care compared with standard treatment alone. The therapy also showed an acceptable safety and tolerability profile consistent with earlier studies, with full data expected to be presented and published in 2026.

Chronic hepatitis B remains a major global health burden, affecting more than 250 million people worldwide, including an estimated 75 million in China. Current standard treatments typically require lifelong use and deliver low functional cure rates of around 1%, underscoring the need for more effective therapies. Functional cure, defined by sustained clearance of viral DNA and hepatitis B surface antigen after treatment cessation, is associated with a reduced risk of severe complications such as liver cancer.

Bepirovirsen has been granted Breakthrough Therapy designation in China, reflecting its potential to offer significant improvements over existing therapies and enabling an accelerated regulatory review pathway. The drug is designed to target and degrade hepatitis B viral RNA, suppress viral replication, reduce surface antigen levels and stimulate immune response, supporting the possibility of sustained disease control without ongoing medication.

The B-Well trials were global, randomised, placebo-controlled studies conducted across 29 countries, evaluating efficacy, safety and durability of response in patients receiving nucleos(t)ide analogue therapy. Results showed particularly strong outcomes in patients with lower baseline hepatitis B surface antigen levels.

Bepirovirsen, licensed from Ionis Pharmaceuticals, is also being developed as a potential backbone for future combination and sequential treatment strategies aimed at expanding functional cure rates across broader patient populations. The therapy has also received Fast Track designation in the US and SENKU designation in Japan, although it is not yet approved in any market.