FDA Approves Gilead’s Hepcludex, Marking a Breakthrough for Patients Living With Chronic Hepatitis Delta
The U.S. Food and Drug Administration (FDA) has granted accelerated approval to Hepcludex® (bulevirtide-gmod) 8.5 mg, developed by Gilead Sciences, for the treatment of adults living with chronic hepatitis delta virus (HDV) infection. The approval represents a landmark achievement in liver disease treatment, making Hepcludex the first and only FDA-approved therapy specifically indicated for HDV in the United States.
The decision addresses a major unmet medical need for patients suffering from one of the most aggressive forms of viral hepatitis. Chronic HDV infection is widely regarded as the most severe type of viral hepatitis because of its rapid progression to advanced liver disease, liver failure, and liver-related death. Until now, patients diagnosed with HDV in the United States had no FDA-approved treatment options specifically targeting the disease.
A Significant Milestone for HDV Patients
HDV is a rare but highly serious liver infection that occurs only in individuals who are already infected with hepatitis B virus (HBV). The virus depends on HBV to replicate and spread, creating a dual viral burden that accelerates liver damage. Compared with HBV infection alone, patients co-infected with HDV face a substantially greater risk of developing liver fibrosis, cirrhosis, liver cancer, hepatic decompensation, and premature death.
Studies estimate that approximately 2% to 4% of Americans living with chronic HBV are also infected with HDV, representing roughly 40,000 to 80,000 individuals in the United States. Globally, at least 12 million people are believed to be living with chronic HDV infection.
For many patients, diagnosis often comes after significant liver damage has already occurred. The disease can progress rapidly, particularly among individuals with cirrhosis, where mortality rates may reach as high as 50% within five years. Healthcare experts have long emphasized the urgent need for therapies capable of slowing disease progression and improving patient outcomes.
FDA Approval Based on Phase 3 MYR301 Trial
The FDA’s accelerated approval of Hepcludex was primarily supported by results from the pivotal Phase 3 MYR301 clinical trial. The study evaluated the efficacy and safety of Hepcludex in adults with chronic HDV infection and included treatment periods of up to 144 weeks, followed by 96 weeks of post-treatment monitoring.
The trial achieved its primary endpoint at Week 48, demonstrating statistically significant improvements compared with a delayed-treatment control group. Investigators observed meaningful reductions in HDV RNA levels together with normalization of alanine aminotransferase (ALT), a key marker of liver inflammation and injury.
These virologic and biochemical improvements formed the basis of the FDA’s accelerated approval decision. However, the agency noted that direct evidence of improved long-term clinical outcomes has not yet been established. As is customary with accelerated approvals, continued approval may depend on confirmation of clinical benefit through ongoing and future studies.
Long-term findings from MYR301 have been encouraging, with sustained antiviral activity and continued efficacy observed through as many as 144 weeks of treatment. The therapy was also generally well tolerated during extended treatment periods.
Expert Views on the Approval
Medical experts have welcomed the approval as a major advancement for patients who previously had limited therapeutic options.
According to Dr. Ira Jacobson of the Department of Medicine at NYU Grossman School of Medicine, HDV infection is associated with rapid deterioration of liver health and a heightened risk of severe liver-related complications. Patients often face the challenge of managing both hepatitis B and hepatitis D simultaneously, creating additional treatment and monitoring complexities.
The availability of Hepcludex provides clinicians with a dedicated treatment option specifically designed to address HDV infection and may help alter the disease course for affected individuals.
How Hepcludex Works
Hepcludex is a first-in-class entry inhibitor that targets a critical step in the lifecycle of both HDV and HBV. Rather than directly attacking viral replication inside infected liver cells, the therapy works by blocking viral entry into hepatocytes, preventing the viruses from infecting new liver cells.
This novel mechanism of action differentiates Hepcludex from many traditional antiviral therapies and offers a targeted strategy for limiting disease progression.
The treatment is supplied as an injectable formulation administered once daily by subcutaneous injection. Each vial contains an 8.5 mg dose prepared according to FDA-approved instructions.
Because HDV relies on HBV for survival and replication, management of underlying HBV infection remains an essential component of patient care. Physicians are advised to continue appropriate HBV treatment and monitoring alongside Hepcludex therapy.
Approved Patient Population
The FDA approved Hepcludex for adults with chronic HDV infection who either do not have cirrhosis or have compensated cirrhosis. The approval was granted under the agency’s accelerated approval pathway, which allows earlier access to promising therapies that address serious diseases and unmet medical needs.
The official indication specifies that approval is based on reductions in HDV RNA and normalization of ALT levels. Demonstration of improvement in disease-related clinical outcomes remains subject to verification in confirmatory studies.
Safety Information and Boxed Warning
The prescribing information for Hepcludex includes a boxed warning regarding severe acute exacerbations of hepatitis D and hepatitis B following treatment discontinuation.
Patients who stop therapy may experience significant disease flare-ups, particularly those with cirrhosis, who face a greater risk of worsening liver function and hepatic decompensation. For this reason, healthcare providers are advised to closely monitor liver function and viral markers, including HBV DNA and HDV RNA levels, for at least six months after treatment cessation. Resumption of antiviral therapy may be necessary in some cases.
Additional safety considerations include the potential for hypersensitivity reactions, including anaphylaxis. If signs of a serious allergic reaction occur, treatment should be discontinued immediately and appropriate medical care initiated.
The most commonly reported adverse reactions in clinical studies included:
- Injection-site reactions
- Headache
- Abdominal pain
- Fatigue
- Pruritus (itching)
Overall, the safety profile observed in clinical trials was considered manageable and consistent with long-term treatment use.
Pregnancy and Breastfeeding Considerations
Data regarding Hepcludex use during pregnancy remain limited. Currently, there is insufficient information from human pregnancies to determine potential risks related to major birth defects, miscarriage, or adverse maternal and fetal outcomes.
Similarly, no data are available concerning the presence of Hepcludex in human breast milk, its effects on nursing infants, or its influence on milk production. Healthcare providers are encouraged to evaluate the benefits and risks of treatment on an individual basis when caring for pregnant or breastfeeding patients.
Expanding Global Access
Although this marks the first FDA approval for Hepcludex in the United States, the therapy is not entirely new to global markets. A 2 mg formulation of bulevirtide has already received authorization in the European Economic Area and several other countries for the treatment of chronic HDV infection.
The U.S. approval further expands access to the therapy and underscores growing international recognition of the urgent need to address HDV.
To support patient access in the United States, Gilead offers assistance through its Gilead Support Path® program. The initiative provides information and resources for patients, caregivers, and healthcare professionals regarding insurance coverage, reimbursement support, and financial assistance programs for eligible individuals.
Commitment to Further Research
As part of the accelerated approval process, Gilead has committed to conducting a confirmatory long-term outcomes study designed to verify and further characterize the clinical benefits of Hepcludex. The study is already underway and will evaluate whether the virologic and biochemical improvements observed in earlier trials translate into meaningful reductions in disease progression, liver-related complications, and mortality.
Successful completion of these studies will play an important role in securing full regulatory approval and expanding understanding of the therapy’s long-term impact.
The approval of Hepcludex marks a transformative moment in the treatment of chronic hepatitis delta. For decades, patients and physicians faced a disease associated with severe outcomes but lacked an FDA-approved therapy specifically designed to treat it. The arrival of Hepcludex introduces a new standard of care and offers hope to thousands of patients living with one of the world’s most aggressive viral liver infections.
While continued research is needed to confirm long-term clinical benefits, the therapy’s demonstrated ability to reduce viral activity and improve liver biomarkers represents a significant advancement in HDV management. As additional evidence emerges from ongoing studies, Hepcludex has the potential to fundamentally change the treatment landscape for chronic hepatitis delta and improve outcomes for patients facing this devastating disease.
About Gilead Sciences in Liver Disease
For decades, Gilead has pioneered the way forward to improve the lives of people living with liver disease around the world. We have helped to transform hepatitis C from a chronic condition into one that can be cured for millions of people. For people living with hepatitis B or D, our focus on advancing our medicines drives hope that today’s research will turn into tomorrow’s cures. Beyond viral hepatitis, we’re working to deliver advanced treatments for people living with PBC. But our commitment doesn’t stop there. Through our ground-breaking science and collaborative partnerships, we strive to create healthier futures for everyone living with liver disease. We are committed to a future without liver disease.
