For patients living with Hepatitis Delta virus infection, the question has never been which treatment to use. There was no approved treatment at all. That changed on May 22, 2026.
The U.S. Food and Drug Administration granted accelerated approval to Hepcludex® (bulevirtide-gmod), an 8.5 mg daily subcutaneous injection developed by Gilead Sciences, for the treatment of chronic Hepatitis Delta Virus (HDV) infection in adults without cirrhosis or with compensated cirrhosis. It is the first and only approved treatment for HDV in the United States — a landmark that the Hepatitis B Foundation called "a game changer."
What Is Hepatitis Delta — and Why Has Treatment Taken So Long?
Hepatitis Delta Virus is a unique pathogen. It can only infect people who already have Hepatitis B Virus (HBV) infection, because HDV requires the HBV surface antigen to form new viral particles and spread. It is, in virology terms, a "satellite virus" — dependent on HBV for its existence but entirely capable of causing devastation on its own.
The consequence of HDV co-infection is severe. According to the FDA, chronic HDV infection is "a serious and life-threatening condition that can cause rapid development of liver fibrosis (scarring), liver cancer, liver failure, and even death." HDV dramatically accelerates the progression of liver disease compared to HBV alone — patients with HBV-HDV co-infection develop cirrhosis and hepatocellular carcinoma at significantly higher rates and younger ages than those with HBV alone.
Globally, an estimated 15–20 million people are infected with HDV. In the United States, the Hepatitis B Foundation estimates that about 4% of the approximately 2 million Americans living with chronic HBV also have HDV — approximately 80,000 people. Most are unaware of their HDV status because HDV testing is not routinely performed during standard HBV management, and because HDV is not widely understood even among general practitioners.
The absence of an approved treatment is, in part, a reflection of how long the disease went without effective pharmacological options. Prior to Hepcludex, physicians had few tools beyond interferon-based therapy — an approach with significant side effects and limited efficacy in HDV. Interferon is not FDA-approved specifically for HDV. For most patients, management was supportive: monitoring liver function, managing symptoms, and awaiting transplant in advanced disease.
How Bulevirtide Works — and What the Phase 3 Trial Showed
Bulevirtide is a first-in-class antiviral agent that works by blocking HDV's entry into liver cells. Specifically, it targets the sodium taurocholate cotransporting polypeptide (NTCP) receptor on the surface of hepatocytes — the receptor that both HBV and HDV use to attach to and infect liver cells. By occupying this receptor, bulevirtide physically prevents new viral particles from entering cells, interrupting the cycle of infection.
The FDA's accelerated approval was based primarily on data from the Phase 3 MYR301 study (NCT03852719), which included 100 adult patients with chronic HDV infection without cirrhosis or with compensated cirrhosis. At Week 48, the study demonstrated a statistically significant improvement in a combined virologic and biochemical response — specifically, reductions in HDV RNA (the amount of virus in the blood) and normalization of alanine aminotransferase (ALT, a marker of liver inflammation) — compared to the delayed treatment control group.
Bulevirtide had previously received Priority Review, Breakthrough Therapy Designation, and Orphan-Drug Designation from the FDA — designations given to therapies addressing serious conditions with unmet medical need.
| HDV and Hepcludex Overview | Data |
| Drug name | Hepcludex® (bulevirtide-gmod) |
| Developer | Gilead Sciences |
| FDA approval date | May 22, 2026 |
| Approval type | Accelerated Approval |
| Indication | Chronic HDV in adults without cirrhosis or with compensated cirrhosis |
| Mechanism | Blocks HDV/HBV entry via NTCP receptor |
| Dosing | 8.5 mg subcutaneous injection, daily |
| Phase 3 trial | MYR301 (NCT03852719); 100 patients |
| Key endpoints | HDV RNA reduction + ALT normalization at Week 48 |
| Prior U.S.-approved treatment for HDV | None |
| EU/UK approval status | Previously approved |
| U.S. patients with HDV (estimate) | ~80,000 |
| Global HDV cases (estimate) | 15–20 million |
Who Needs to Be Tested — and Why Most People With HDV Don't Know It
"Until now, there was very little that we could do to prevent cirrhosis and liver cancer for people living with hepatitis delta in the U.S.," said Chari A. Cohen, DrPH, MPH, President of the Hepatitis B Foundation. "All of us at the Hepatitis B Foundation are optimistic that the FDA's approval of Hepcludex will be a game changer, leading to improved HDV screening, diagnosis, care and treatment across the U.S."
The approval also creates an urgent reason to address HDV's profound underdiagnosis problem. Because HDV can only occur in people with HBV, every person who knows they have chronic Hepatitis B should ask their provider about HDV testing — a simple blood test that checks for antibodies to HDV and, if positive, for HDV RNA to confirm active infection.
HDV disproportionately affects people from HDV-endemic regions, including Central Asia, the Middle East, sub-Saharan Africa, Mongolia, Pakistan, the Mediterranean basin, and parts of South America. In the United States, foreign-born individuals with HBV are at the highest risk, as are people who inject drugs — a transmission pathway through which HBV and HDV can spread simultaneously. In major metropolitan areas with large immigrant populations — New York, Los Angeles, Chicago, Houston, Miami, Boston, and San Francisco among them — the number of undiagnosed HDV cases is almost certainly higher than national estimates suggest.
"Today's approval fills a critical gap in care for patients with chronic HDV infection, who until now have had no FDA-approved therapies available," said Wendy Carter, D.O., Acting Director of the Office of Infectious Diseases in the FDA's Center for Drug Evaluation and Research.
Important Limitations and What Comes Next
Hepcludex received accelerated approval — meaning continued approval is contingent on the verification and description of clinical benefit in a confirmatory trial. Improvement in disease-related clinical outcomes, such as prevention of cirrhosis progression or reduction in liver cancer rates, has not yet been established. Gilead is required to conduct and complete a post-marketing confirmatory trial.
The drug is administered as a daily subcutaneous (under the skin) self-injection. Patients and caregivers can administer it at home after receiving training on proper technique — a model similar to insulin injections for diabetes. It is approved for adults; pediatric data is not yet available.
Hepcludex was previously approved in the European Union and United Kingdom, giving physicians in those countries several years of real-world experience with the drug's safety and efficacy profile before the U.S. approval — a track record that adds context to the Phase 3 data.
Frequently Asked Questions
What is Hepcludex (bulevirtide) and what was it approved for?
Hepcludex (bulevirtide-gmod) is the first FDA-approved treatment for chronic Hepatitis Delta Virus (HDV) infection in the United States. Approved on May 22, 2026, it is indicated for adults without cirrhosis or with compensated cirrhosis who have chronic HDV infection. It is a daily subcutaneous injection manufactured by Gilead Sciences.
What is Hepatitis Delta Virus, and how is it different from Hepatitis B?
HDV is a satellite virus that can only infect people who already have Hepatitis B Virus (HBV), because it requires the HBV surface antigen to replicate. Co-infection with both viruses dramatically accelerates liver scarring, liver failure, and liver cancer compared to HBV alone. HDV is considered the most severe form of viral hepatitis.
Who in the United States has Hepatitis Delta?
Approximately 80,000 Americans are estimated to have HDV co-infection, based on a prevalence of about 4% among people with chronic HBV. Most are unaware. HDV is more common among people from endemic regions (Central Asia, the Middle East, Mongolia, sub-Saharan Africa, South America) and people who inject drugs.
Should I get tested for HDV?
If you have chronic Hepatitis B, yes — ask your provider about HDV antibody testing. HDV is not routinely tested during standard HBV management, so many co-infected patients are never diagnosed. A positive antibody test is followed by HDV RNA testing to confirm active infection.
How does bulevirtide work?
Bulevirtide blocks the NTCP receptor on liver cell surfaces — the receptor that both HBV and HDV use to enter and infect liver cells. By occupying this receptor, bulevirtide prevents new viral particles from entering cells, reducing viral load and liver inflammation.
