FDA approves GSK hepatitis B drug that can keep virus in check after treatment ends

The Food and Drug Administration has approved bepirovirsen, a GSK drug for chronic hepatitis B. In clinical trials, some patients who took it were able to stop all treatment while the virus stayed undetectable in their blood.

The drug will be sold under the brand name Hibsago. GSK calls it the first "functional cure" for the disease. The company uses that term to mean the virus is pushed down to levels that blood tests cannot detect, and that this control continues in patients who respond even after the drug is stopped. Existing hepatitis B medicines manage the virus, but they do not keep it suppressed once patients stop taking them.

Chronic hepatitis B is a long-term liver infection that can cause scarring, liver failure or cancer. It is responsible for more than a million deaths around the world each year. Chari Cohen, president of the Hepatitis B Foundation, said the disease affects millions of people in the U.S. and accounts for roughly 56% of liver cancer cases worldwide.

The approval follows two phase 3 trials, with results published in the New England Journal of Medicine. Among 1,220 participants who received a six-month course of bepirovirsen, 233, or 19%, reached a functional cure response. None of the 614 participants given a placebo did.

In the patients who responded, the virus remained undetectable for at least 24 weeks after every treatment had ended. That checkpoint came 72 weeks after the trials started.

Bepirovirsen is given as a weekly injection. In the trials, patients received it on top of the antiviral pills they were already taking. Those who responded could then stop the pills as well.

Tony Wood, GSK's chief scientific officer, said U.S. patients could reach functional cure after six months of treatment, "with the added convenience of the option of self-administration after the first dose."

For many people with the disease, treatment has meant years of antiviral medication to keep the virus under control, said Wendy Carter, acting director of the FDA's Office of Infectious Diseases. She said Hibsago gives some patients a chance to keep the virus in check after they stop all chronic hepatitis B treatment.

"This approval represents an important advance for people living with this serious disease," Carter said.

Norah Terrault, a gastroenterologist at the Keck Medical Center of the University of Southern California, said the drug gives patients the potential for a functional cure after a short course of treatment, "a long-standing goal for patients and physicians alike."

The drug has clear limits. Most trial participants did not reach a functional cure. Some patients had serious side effects, including liver inflammation, and the FDA says patients should get regular blood tests to watch for it.

Traces of the virus also remain in the body after treatment. Researchers have not yet shown whether the response holds for years once treatment ends.

Some patients were more likely to respond than others. People who started treatment with lower levels of a key hepatitis B protein, a sign of a less active infection, had a better chance of success. Doctors could test for that protein before prescribing the drug.

Researchers plan to study whether combining bepirovirsen with other drugs could make it more effective. GSK said it wants to make the treatment available to more patients around the world.