GlaxoSmithKline (GSK) is one step closer to bringing patients a functional cure for chronic hepatitis B
An experimental drug being developed by GlaxoSmithKline to treat chronic hepatitis B has now received results from two pivotal studies showing that the treatment reduces virus levels enough for the immune system to control the infection without further medication.
This result amounts to a functional cure, with the virus no longer detectable in the blood. GlaxoSmithKline said on Wednesday that the drug, bepirovirsen, achieved a statistically significant and clinically meaningful functional cure rate, meeting the study's primary goal, without releasing specific data. With preliminary data in hand, the company is now preparing regulatory applications for the drug worldwide.
Hepatitis B virus can cause acute and chronic liver disease. When the immune system is unable to clear the virus, the infection becomes chronic. It is estimated that more than 250 million people worldwide have chronic hepatitis B infection, which can lead to liver cancer. The standard treatment is antiviral therapy, such as Gilead Sciences' Vemlidy, which must be taken long-term and has a low functional cure rate. Gilead announced that global sales of Vemlidy in the first nine months of 2025 were US$783 million, an increase of 12% from the same period last year.
Bepirovirsen is an antisense oligonucleotide designed to target RNA and inhibit the production of proteins associated with hepatitis B virus infection and replication. GlaxoSmithKline said that in addition to inhibiting the replication of viral DNA, the drug suppresses hepatitis B surface antigen levels in the blood and stimulates the immune system, increasing the chance of a durable response to treatment.
Preliminary data released Wednesday came from two Phase 3 studies enrolling more than 1,800 patients from 29 countries. The treatment cycle is 24 weeks. GlaxoSmithKline said the study drug plus standard-of-care antiviral drugs resulted in significantly higher rates of functional cure compared with standard therapy alone. The company added that if approved, bepiprovirsen could become the first limited, six-month therapy to treat chronic hepatitis B infection. Complete clinical trial results will be presented to an upcoming scientific meeting and published in a peer-reviewed journal.
“Today's results support our plans to develop bepirovirsen as a treatment and continue to develop it as a backbone of future sequential therapies,” Tony Wood, GlaxoSmithKline's chief scientific officer, said in a prepared statement. “We are pleased with this significant advancement of our expanding hepatology pipeline, designed to transform outcomes in liver disease.”
Bepirovesan comes from Ionis Pharmaceuticals Laboratories. In 2010, Ionis began a drug discovery partnership with GSK, which included the area of infectious diseases. After bepirovirsen posted positive Phase 2 results in 2019, GlaxoSmithKline (GSK) licensed the HBV program, putting the major pharma company in charge of the drug's further development and regulatory submissions globally. Ionis said in its 2024 annual report that it has received more than $105 million in payments from the collaboration to date.
Leerink Partners analyst Mani Foroohar wrote in a note to investors that the positive data for bepirovirsen was largely expected given the successful results from the second phase of the program. The company is awaiting detailed data before valuing the asset. He added that while chronic hepatitis B represents a large, underserved market, commercial opportunities will depend on how antisense oligonucleotide/siRNA therapeutics are positioned in this market. Foroohar said Ionis could receive up to $150 million in remaining milestone payments as well as royalties on sales of Bepiroveson.
Public domain image from CDC
