First Hepatitis B Functional Cure Wins FDA Approval

For the first time, people living with chronic hepatitis B have a real shot at stopping treatment altogether. The First Hepatitis B Functional Cure has won FDA approval, clearing GSK's Hibsago as the first antisense drug ever approved for the disease, according to the FDA. The agency granted approval on October 20, 2026, after reviewing two phase 3 trials in which nearly one in five treated patients kept the virus under control after discontinuing all hepatitis B medicine. The injections are given under the skin over a half-year course, and patients can administer later doses themselves.

Chronic hepatitis B has always been a managed condition, never a finished one. Standard antiviral pills suppress the virus but rarely clear it, which means most patients take medicine indefinitely. Hibsago takes a different route: its active ingredient, bepirovirsen, is an antisense oligonucleotide designed to interfere with the virus's genetic instructions. That mechanism makes it the first of its kind for this disease. For more on the wave of October drug decisions, see our story on the first new herpes drug in decades and the first heart drug cleared for teens with a rare condition.

What the trials actually showed

GSK's case rests on two placebo-controlled phase 3 studies, B-Well 1 and 2, in which patients stayed on their existing antiviral pills while receiving the new injections. Across the trials, 24 percent of Hibsago recipients met the requirements to stop their older antiviral medicine. None of the patients on placebo did. Six months after stopping all hepatitis B treatment, 19 percent of the treated group still had the virus under control, with surface antigen undetectable in their blood.

Those numbers look modest until you compare them with the status quo. GSK said typical functional cure rates after a year of existing therapy sit below one percent, and the new data showed response rates nearly doubling in patients who started with lower antigen levels. In exploratory analyses, the drug drove surface antigen down to very low levels in roughly half of the overall study population, and in more than three in five of those who started at the lowest levels. GSK's chief scientific officer said in a company statement, as reported by PharmExec, that US patients now have "the potential to achieve functional cure after a six-month treatment course, with the added convenience of the option of self-administration after the first dose."

Who can get it, and who can't

The First Hepatitis B Functional Cure comes with a deliberately narrow label.

The label is deliberately narrow. Hibsago is approved for adults without cirrhosis who have been on antiviral therapy for at least half a year, have suppressed virus in the blood, and show surface antigen at or below 3,000 international units per milliliter on an authorized test, according to Nova Pharma News. Patients continue their existing antiviral during the injection course and for at least another 24 weeks after the final dose; only those whose labs hold up can then stop the older medicine, under medical supervision.

The approval also carries the FDA's most serious safety label. The drug has a boxed warning for severe liver reactions and for low platelet counts, which can raise the risk of life-threatening bleeding. Other warnings cover worsening kidney function and serious inflammatory reactions such as vasculitis, and patients need regular blood tests before and during treatment. The three most common side effects in the trials were redness where the needle went in, local pain, and a temporary rise in a liver enzyme, GSK said. The medicine is contraindicated for people with cirrhosis or acute liver impairment, and regulators in Japan had already approved it before the US decision.

Why a fixed course changes the math

The practical difference here is psychological as much as medical. A daily pill you take forever is easy to deprioritize, easy to resent, and easy to stop taking quietly. A defined course of injections with a finish line, even one that only works for a fraction of patients, gives people something the disease has historically denied: an endpoint. That matters for a condition that touches about 1.7 million people in the US, by the company's estimate, many of whom were diagnosed young and expect decades of treatment.

The counterpoint is that the finish line is narrow. Four in five treated patients did not reach a functional cure, the eligibility tests exclude anyone with advanced liver damage, and the boxed warning means this will remain a tightly managed prescription. Pricing and insurance coverage were not announced, and the FDA's decision covers only the United States, with submissions elsewhere still pending. Even so, regulators moved unusually fast: the application carried Fast Track, Breakthrough Therapy, and Priority Review designations. For a virus that has outlasted every attempt at a cure, a one-in-five shot at walking away from daily medicine is the most meaningful progress the field has seen in years. Our health desk also covered new evidence linking ultra-processed food to brain changes this month.