The U.S. Food and Drug Administration (FDA) has given the green light to a novel therapy called Hibsago, designed to treat chronic hepatitis B. In clinical trials, nearly 20% of patients managed to keep their infection under control for at least 24 weeks after ceasing all medications.
Developed through a collaboration between pharmaceutical giant GSK and Ionis Pharmaceuticals, Hibsago is the first treatment of its kind approved in the U.S. to combat this infection, as announced by the FDA on October 20.
How Hibsago Differs from Traditional Antivirals
Unlike conventional antivirals that require prolonged use, Hibsago targets the virus's genetic material, reducing viral protein production and aiding the body in controlling the infection. It is specifically for adults without cirrhosis, who have been on antiviral treatment for at least six months, have a suppressed viral load, and exhibit hepatitis B surface antigen (HBsAg) levels of 3,000 IU/mL or lower, as determined by an FDA-approved test.
Clinical Trial Insights: Hibsago's Impact
The FDA's approval is grounded in two clinical trials involving over 1,800 patients across 29 countries. According to the FDA, 24% of those treated with Hibsago met the medical criteria to halt their previous antiviral treatments, compared to none in the placebo group. Notably, 19% of patients maintained virus control without detectable surface antigen for at least 24 weeks after stopping all medications.
This outcome is termed a functional cure: the virus's DNA and surface antigen remain undetectable for at least 24 weeks without ongoing treatment, although it doesn't imply a complete eradication of the virus from the body.
Administration and Potential Risks of Hibsago
Hibsago is administered via subcutaneous injections for up to 24 weeks, alongside existing antivirals, which should continue for at least 24 weeks post-final injection. Discontinuation of these antivirals is conditional on meeting specific clinical and laboratory benchmarks, under medical guidance.
The FDA has highlighted warnings regarding severe hepatic reactions and a concerning drop in platelet count, which could lead to life-threatening bleeding. Additionally, there are cautions about potential kidney function alterations and severe inflammatory responses, such as vasculitis. Common side effects include injection site reactions, fever, fatigue, and headaches.
The Broader Context of Chronic Hepatitis B
Chronic hepatitis B can lead to cirrhosis and liver cancer. According to the Centers for Disease Control and Prevention (CDC), an estimated 660,000 people in the U.S. were living with this infection between 2017-2020, with about half unaware of their condition.
While Hibsago is not a definitive cure or a substitute for standard treatments for all patients, its approval offers a new avenue for those who might control the infection without continuous medication.
Understanding Hibsago and Its Implications for Hepatitis B Treatment
What makes Hibsago different from traditional hepatitis B treatments?
Hibsago differs from typical antivirals by targeting the virus's genetic material, which reduces viral protein production and helps the body control the infection without the need for prolonged antiviral use.
Who is eligible for Hibsago treatment?
Hibsago is intended for adults without cirrhosis, who have been receiving antiviral treatment for at least six months, have a suppressed viral load, and show hepatitis B surface antigen levels of 3,000 IU/mL or lower.
What are the potential risks associated with Hibsago?
Potential risks include severe hepatic reactions, significant decreases in platelet count, possible kidney function alterations, and severe inflammatory responses. Common side effects may include injection site reactions, fever, fatigue, and headaches.