The U.S. Food and Drug Administration (FDA) approved Hibsago, a new treatment for chronic hepatitis B that enabled nearly one in five patients treated in two clinical trials to maintain control of the infection for at least 24 weeks after stopping all medication.
The medication, marketed by the pharmaceutical company GSK, which collaborated in its development with Ionis Pharmaceuticals, is the first of its kind authorized in the country to treat this infection, according to the FDA announcement on Tuesday, October 20.
Unlike conventional antivirals, which many people must take for years, Hibsago targets the virus's genetic material to reduce the production of viral proteins and help the body keep the infection under control.
Its use is limited to adults without cirrhosis who have been receiving antiviral treatment for at least six months, have suppressed viral load, and present hepatitis B surface antigen (HBsAg) levels equal to or less than 3,000 IU/mL, determined through a test authorized by the FDA.
What results did the new treatment achieve?
The approval was based on two clinical trials conducted with over 1,800 patients from 29 countries.
According to the FDA, 24% of those who received Hibsago met the medical criteria to discontinue their previously prescribed antivirals, compared to none of the participants treated with placebo.
The most significant result was that 19% of the treated patients managed to keep the virus under control and without detectable surface antigen for at least 24 weeks after stopping all medications.
This result is known as a functional cure: the virus's DNA and surface antigen remain undetectable for at least 24 weeks without treatment, although that does not mean the virus has been completely eradicated from the body.
"For many people living with chronic hepatitis B, treatment can involve taking antiviral medications for years," explained Wendy Carter, Acting Director of the FDA's Office of Infectious Diseases.
How is it administered and what are its risks?
Hibsago is administered through subcutaneous injections for a maximum of 24 weeks, combined with the standard antivirals, which must be continued for at least another 24 weeks after the last injection.
The subsequent suspension of those medications can only occur when certain clinical and laboratory criteria are met, under medical supervision.
The FDA included prominent warnings about the risk of severe liver reactions and dangerous decreases in platelets, which can lead to potentially fatal bleeding. It also alerted to possible alterations in kidney function and severe inflammatory reactions, such as vasculitis.
The most common side effects include reactions at the injection site, fever, fatigue, and headache.
Chronic hepatitis B is an infection that can lead to cirrhosis and liver cancer. According to the Centers for Disease Control and Prevention (CDC), around 660,000 people were living with this infection in the United States, based on estimates from the period 2017-2020, and approximately half were unaware of their diagnosis.
Although the new medication does not represent a definitive cure nor does it replace the usual treatments for all patients, its approval offers an alternative for those who could manage the infection without continuous medication.
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