FDA Approves Hibsago, the First Functional Cure Option for Hepatitis B

For most of the roughly 1.7 million Americans living with chronic hepatitis B, treatment has meant a pill every day, often for life. The drugs keep the virus quiet, but stop taking them and it usually comes back. This week the Food and Drug Administration approved a medicine that could change that for some patients.

The drug, Hibsago, known generically as bepirovirsen, comes from GSK and was originally discovered by California's Ionis Pharmaceuticals. In late-stage trials, about one in five eligible patients kept the virus under control even after stopping all hepatitis B treatment, an outcome doctors call a functional cure. For the Bay Area, where hepatitis B weighs heavily on Asian American families, the news lands close to home.

What the FDA Approved

Hibsago is approved for adults with chronic hepatitis B who do not have cirrhosis, have been taking standard antiviral pills for at least six months, have the virus suppressed in their blood and have a hepatitis B surface antigen level of 3,000 IU/mL or lower. It is used together with those existing antivirals, not in place of them.

It is the first antisense oligonucleotide the FDA has approved for chronic hepatitis B. Antisense drugs are short strands of genetic material designed to latch onto the virus's genetic instructions, cutting the amount of virus and viral protein the liver produces. Treatment is a six-month course of injections under the skin, and patients can give the shots themselves after the first dose.

The FDA also authorized a Roche blood test, the Elecsys HBsAg II quant II RxDx assay, as a companion diagnostic to pick the right patients and monitor them during treatment. "This approval represents an important advance for people living with this serious disease," said Wendy Carter, acting director of the FDA's Office of Infectious Diseases.

How Well It Works

The approval rests on two global Phase 3 trials, B-Well 1 and B-Well 2, run in 29 countries. Among patients with a surface antigen level of 3,000 IU/mL or lower, 19 percent of those who received Hibsago reached a functional cure, compared with none on placebo. In patients with lower levels, 1,000 IU/mL or less, the rate rose to 26 percent.

Functional cure here means the virus stayed undetectable and the surface antigen disappeared from the blood 24 weeks after patients stopped all hepatitis B medicine. GSK says standard treatment alone achieves that in fewer than 1 percent of patients after a year.

The drug carries a boxed warning for serious liver reactions and low platelet counts, which can raise the risk of dangerous bleeding, so patients need regular blood tests during treatment. The most common side effects were injection site reactions, fever, fatigue and headache. "For the first time, with Hibsago, US patients have the potential to achieve functional cure," said Tony Wood, GSK's chief scientific officer. Japan approved the drug first, and GSK says decisions from regulators in several other regions are expected in the coming months.

A Disease That Hits Close to Home

Hepatitis B is a worldwide problem, with more than 240 million people living with chronic infection and about 1.1 million deaths a year, according to GSK. It is the leading cause of liver cancer worldwide. In the United States, Asian Americans and Pacific Islanders account for about half of people living with chronic hepatitis B, many of them infected at birth.

That makes the disease a local issue in the Bay Area. Stanford's Asian Liver Center has spent decades on hepatitis B awareness and screening, and San Francisco launched its Hep B Free campaign in 2007 to test and vaccinate residents. Many people in the region's Taiwanese, Chinese, Korean, Vietnamese and Filipino communities know someone who takes a daily hepatitis B pill.

Taiwan, which once had some of the highest infection rates in the world, began one of the first national hepatitis B vaccination programs for newborns in the 1980s, and liver cancer rates among vaccinated generations fell sharply. Vaccines prevent new infections, but they do nothing for the millions of adults who already carry the virus, which is exactly the group Hibsago aims to help.

Why Silicon Valley Is Paying Attention

Hibsago will be used alongside the daily antivirals that most patients take today, a market led by Gilead Sciences of Foster City, whose tenofovir drugs are among the most prescribed hepatitis B treatments, and the company has long researched approaches to a cure. Ionis, based in Carlsbad near San Diego, discovered bepirovirsen and licensed it to GSK in 2019, and it will earn royalties on sales.

The approval is also a win for a style of drug discovery that looks a lot like software. Antisense medicines are designed by writing a sequence that matches a target gene, and companies across California are building platforms that use computation and AI to design such sequences faster. A pairing of a new drug with a companion diagnostic, as here, also points to a future where treatment decisions depend on precise data about each patient.

Will Hepatitis B Become Curable for Most Patients?

The prospects are encouraging. For the first time, a meaningful share of patients may be able to stop treatment altogether, which could reduce lifelong drug costs and the burden of daily pills. Researchers are already testing combinations of antisense drugs, immune boosters and other new approaches that could push cure rates higher, and Hibsago gives them a new baseline to build on. Patients with lower surface antigen levels, about 45 percent of diagnosed cases worldwide according to GSK, appear to benefit most.

There are real concerns as well. Four in five eligible patients in the trials did not reach a functional cure, and people with cirrhosis are not eligible at all. The boxed warning means patients need close monitoring, weekly platelet checks and access to a specialist, which may be hard to find outside major medical centers. GSK has not announced a price, and insurers will decide how easy the drug is to get.

There is also a question of reach. Many people with hepatitis B in the United States do not know they are infected, and many who do are not in regular care. A breakthrough drug helps only those who are screened, diagnosed and treated, so community testing programs like those in San Francisco will matter as much as the medicine itself. Globally, most people with hepatitis B live in Asia and Africa, where access to new and costly drugs is limited.

Competition and follow-on science will shape the field. San Francisco's Vir Biotechnology is developing treatments for hepatitis delta, a more severe infection that only occurs in people who already have hepatitis B, and other companies are testing therapeutic vaccines and gene-silencing drugs. If several approaches work, doctors may one day combine them the way HIV treatment evolved, tailoring therapy to each patient's virus and immune response.

The signals to watch are specific. How will GSK price Hibsago, and how quickly will insurers cover it? How many patients will meet the eligibility criteria in real-world practice? Will regulators in China, where hepatitis B is most common, approve it after granting it priority review? And will combination treatments in development raise the functional cure rate well beyond one in five?

Health Breakthroughs That Reach Everyone

At Sparknify we follow how science and policy decide who benefits from medical progress. Earlier today we looked at Executive Order Creates NIH Women's Health Division, where the question was which patients get studied and served. Hepatitis B raises the same issue for Asian American and immigrant communities across the Bay Area, who have waited decades for a treatment that could let them stop.

For one in five eligible patients, a daily pill could finally become a six-month course with an end date.

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