New hepatitis B shot approved in US lets some patients stop all medication

For most people with chronic hepatitis B, treatment means a daily antiviral pill for life. It keeps the virus in check but almost never clears it. In the US, some of those patients will now have the option of a six-month course after which they may be able to stop everything.

The US Food and Drug Administration (FDA) approved Hibsago (bepirovirsen), from GSK and developed with Ionis, on 20 October. It is the first drug of its kind for the disease: an antisense oligonucleotide, a short strand of genetic material that blocks the instructions the virus uses to make its proteins. Japan had already approved it, and GSK expects decisions in other countries in the coming months.

Six months of injections, then no treatment

The drug is injected under the skin for 24 weeks alongside standard antivirals, which continue for at least another 24 weeks after the last dose. In the trials, it was given weekly.

The results come from two phase 3 trials, B-Well 1 and B-Well 2, involving 1,834 adults:

• 24% of those given bepirovirsen met the criteria to stop their antiviral. On placebo, nobody did.
• 19% (233 of 1,220) reached what doctors call a functional cure: six months after stopping all medication, the virus was still undetectable in the blood and its surface antigen had gone. On placebo, none of 614.
• Among those who started with lower antigen levels (1,000 IU/mL or less), the figure rose to 26%.

With standard treatment, according to GSK, fewer than 1% reach functional cure after a year.

Who it is for, and what to watch

Only adults without cirrhosis can receive it, and only if they have been on antivirals for at least six months, have a suppressed virus and an antigen level of 3,000 IU/mL or less, measured with an authorised test. A functional cure does not mean the virus has left the body entirely, and how long the effect lasts is not yet known.

The label carries a boxed warning for serious liver reactions and low platelet counts, so regular blood tests are needed. The most common side effects were redness and pain at the injection site, fever, tiredness, headache and a temporary rise in a liver enzyme.

Chronic hepatitis B affects more than 240 million people worldwide and causes about 1.1 million deaths a year, according to GSK. “This is the start of a new era in treating people living with CHB,” said Dr Norah Terrault, a liver specialist at USC’s Keck Medical Center, in GSK’s announcement. Next come decisions by regulators elsewhere, including China, which has already given it priority review.