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New hepatitis delta drug, Hepcludex, now approved in the U.S.

 

 

 

 

 

What you need to know

| Stella Dlamini

The recent U.S. Food and Drug Administration (FDA) approval of Hepcludex (bulevirtide) marked a major breakthrough in the fight against hepatitis delta. Conservative estimates suggest that approximately 4% of people living with chronic hepatitis B in the United States (U.S.) are also infected with hepatitis delta [1]. This translates to about 80,000 people. For all these people, the drug’s approval represents the first time they can access an effective, FDA-approved treatment for their condition.

What is hepatitis delta?

Discovered nearly 50 years ago, hepatitis delta is a small virus that infects individuals who are living with hepatitis B, or those who acquire both the hepatitis B and hepatitis delta viruses at the same time. The virus is transmitted through exposure to the blood and body fluids of an infected person. Hepatitis delta infection causes the most severe form of viral hepatitis, often leading to rapid disease progression and significantly increasing the risk of severe liver injury and liver cancer if left untreated. In 2025, hepatitis delta was officially classified as a class I carcinogen to humans by the International Agency for Research on Cancer (IARC) [2], owing to its association with increased risk for liver cancer. This classification reflects years of advocacy and evidence showing that people living with hepatitis delta are two-to-six times more likely to develop liver cancer than people living with hepatitis B infection alone.

How does Hepcludex work?

Hepcludex is a viral entry inhibitor and the only FDA-approved treatment for chronic hepatitis delta. Rather than attacking the virus directly, it prevents hepatitis delta from entering liver cells by blocking special protein entry points (known as NTCP receptors) located on the surfaces of liver cells. By preventing new liver cells from becoming infected, the drug helps reduce viral replication and limits ongoing liver injury.

Hepcludex is approved for adults aged 18 and older without cirrhosis or those with compensated cirrhosis, a stage where the liver is injured but continues to retain its functions. Hepcludex is administered as a once-daily subcutaneous injection (injected into the fatty tissue under the skin), typically into the lower abdomen or upper thigh. After appropriate training from a health care professional, many individuals can safely self-administer the medication at home.

Gilead, the manufacturer of Hepcludex, advises that once treatment with Hepcludex has been started, it should not be stopped without first discussing it with a health care provider. Stopping treatment may increase the risk of a ‘flare-up’, where the virus may become active again.

What did clinical trials show?

The FDA approval was supported by Phase 3 clinical trials conducted across the U.S, Germany, Italy, Russia and Sweden.

48% of participants on Hepcludex experienced a significant decline in hepatitis delta viral load (or 2 log reduction in hepatitis delta RNA) and alanine aminotransferase (ALT) normalization, compared to just 2% in the group of participants who had treatment initiation delayed. Importantly, these outcomes were maintained for 144 weeks (approximately three years) for those who received early treatment [3].

While Hepcludex reduces the hepatitis delta viral load, it does not directly affect the hepatitis B viral load, so it is important to maintain standard care for hepatitis B infection when getting treatment for hepatitis delta.

What does this mean for people living with hepatitis B and delta?

Despite hepatitis delta being the most severe form of viral hepatitis, fewer than 11% of people living with chronic hepatitis B are estimated to have ever been tested for the virus in the U.S. [4]. Since hepatitis delta can only occur in people with hepatitis B, anyone living with chronic hepatitis B should discuss hepatitis delta testing with their health care provider. With effective treatment now available, there is a massive opportunity to get tested for hepatitis delta, identify infection and receive treatment early.

Individuals already diagnosed with hepatitis delta should speak with their health care provider to determine whether they are eligible for Hepcludex treatment. Gilead has a Support Path Program created to assist individuals with navigating insurance and financial support for accessing the treatment, including for eligible uninsured individuals.

What does this mean for health care providers?

The availability of an effective drug is also an opportunity to change the approach to hepatitis delta care in clinical practice. Health care providers should proactively identify patients at risk by testing all people living with hepatitis B for hepatitis delta. Hepatitis delta diagnostic capacity has expanded in the U.S., and tests are available to order from multiple labs. Providers should now also make efforts to ensure their eligible patients are started on Hepcludex as soon as possible.

Of course, vaccination against hepatitis B for those who are not infected remains a paramount preventative step, which ensures that individuals are protected from hepatitis B, without which hepatitis delta infection cannot occur.

This approval marks a significant change for everyone involved in hepatitis delta. The next challenge is ensuring that those who stand to benefit from this breakthrough are identified, diagnosed and connected to treatment with no delays. To learn more about hepatitis delta, please visit Hepatitis Delta Connect.

References:

1. Gish RG. Delta hepatitis in the United States: epidemiology, testing, and linkage to care. Gastroenterol Hepatol (N Y). 2023 Oct;19(10):603-605. PMID: 38404959; PMCID: PMC10882855.

2. World Health Organization. WHO urges action on hepatitis, announcing hepatitis D as carcinogenic [Internet]. Geneva: World Health Organization; 2025 Jul 28 [cited 2026 Jul 9]. Available from: https://www.who.int/news/item/28-07-2025-who-urges-action-on-hepatitis-announcing-hepatitis-d-as-carcinogenic

3. Gilead Sciences. FDA grants accelerated approval to Gilead’s Hepcludex® (bulevirtide-gmod), the first and only approved treatment for chronic hepatitis delta virus (HDV) [Internet]. Foster City (CA): Gilead Sciences; 2026 May 22 [cited 2026 Jul 9]. Available from: https://www.gilead.com/news/news-details/2026/fda-grants-accelerated-approval-to-gileads-hepcludex-bulevirtide-gmod-the-first-and-only-approved-treatment-for-chronic-hepatitis-delta-virus-hdv

4. B. V. John, M. M. Amoli, D. M. Evon, R. Wong, and B. Dahman, “Hepatitis Delta Testing Trends in a US National Cohort: An Analysis of Patient and Provider- Level Predictive Factors,” Hepatology Communications 8, no. 5 (2024): e0401.

 

2022 – The Year of Hepatitis Delta

2022 is shaping up to be a big year for hepatitis delta, the rare but serious virus that can co-infect people who are already living with hepatitis B. As a quick refresher, hepatitis delta is a virus that depends upon the hepatitis B virus in order to survive and replicate – so only those who are already living with hepatitis B can become infected with hepatitis delta. Hepatitis delta virus (HDV) is believed to infect between 5 and 10% of people living with hepatitis B virus (HBV). HDV can occur through either a superinfection or a coinfection. A superinfection occurs when someone who is already living with HBV contracts HDV, in which case there is a very high chance that the individual will develop chronic (lifelong) infections of both HBV and HDV. A coinfection occurs when both HBV and HDV are contracted at the same time – when this happens in adults, both infections tend to clear within six months and there is only a 5% chance that chronic HBV and HDV will occur. Chronic HDV is particularly dangerous because it advances progression to serious liver damage and liver failure much more quickly than HBV alone – 70% of people diagnosed with HDV and HBV will experience serious liver damage within 10 years without intervention, compared to 15-30% of people diagnosed with HBV alone.

So, What’s Happening in the World of Hepatitis Delta?

The past 18 months have been very important for hepatitis delta research and drug development. In July of 2020, the European Medicines Agency approved Hepcludex, the first-ever drug approved for treatment of hepatitis delta, for prescription in France, Austria, and Germany. Hepcludex works by stopping HDV from entering and infecting liver cells (and is known as an entry inhibitor). In 2021, MYR Pharma, the German company that originally developed Hepcludex, was bought by Gilead Sciences, Inc., which is based in the United States, and which has since filed a Biologics Licensing Agreement for approval of Hepcludex by the US Food and Drug Administration, which is expected later this year. At this time, there is not a timeline for when Hepcludex approval will be expanded to more countries and parts of the world. Prior to Hepcludex, the only drug available for hepatitis delta management, which was never officially approved, was called pegylated interferon alpha. This drug, still in use today, is only effective in controlling HDV in about 25% of people living with the virus and has challenging side effects that can negatively impact quality of life.

In addition to Hepcludex, two other promising drugs are in clinical trials, both developed by Eiger BioPharma in the United States. The first of these is called Lonafarnib, which is being evaluated for how well it works to target the protein assembly process, which keeps new viruses from being created (it is known as a prenylation inhibitor). Lonafarnib, in combination with another drug called Ritonavir, is currently in Phase III clinical trials (the phase in which the safety and effectiveness of a drug is compared to that of currently available treatments). These trials are fully enrolled, and data is expected by the end of 2022. Additionally, Eiger is currently enrolling phase III clinical trials for Pegylated Interferon Lambda, which works by stimulating the body’s own immune system to fight the virus. For a full list of drugs under investigation for hepatitis delta, including one from Janssen Research and Development and one from Antios Therapeutics, visit our Drug Watch page.

Are There Other Clinical Trials Happening for Hepatitis Delta?

 Yes! There are clinical trials happening worldwide to test many of the drugs listed above and more. You can check out our clinical trials page here. This page includes a detailed description of each clinical trial, along with information about where it is being conducted and how to contact the principal investigator (or person leading the clinical trial). This page also includes a helpful graphic describing the clinical trial process and what it takes for a drug to move from an idea into the real world. It is important to note that not all of the trials listed here are for the purpose of testing a medication – some are observational studies to monitor what are called disease biomarkers, which are physical measures used to monitor the progress of a disease and could include tests of blood or liver function, for example. Clinical trials are currently happening in Australia, Austria, Belgium, Brazil, Bulgaria, Canada, China, France, Georgia, Germany, Greece, Israel, Italy, Japan, Mongolia, New Zealand, Pakistan, Republic of Moldova, Romania, Russian Federation, Spain, Sweden, Switzerland, Taiwan, Turkey, Ukraine, the United Kingdom, the United States, and Vietnam.

When Will HDV Drugs and Clinical Trials Be More Accessible in More Parts of the World?

 This is unfortunately a difficult question to answer. Even though up to 10% of people who are living with hepatitis B are also living with hepatitis delta, there are not good systems in place to make sure that everyone who is living with HBV or who is at increased risk for HDV is tested and diagnosed, so there are not very accurate numbers about how many people in the world are living with HDV. Indeed, of the nearly 300 million people around the world who are living with hepatitis B alone, only 10% are aware of their diagnosis, so this number is undoubtedly far lower than even 10% for hepatitis delta. Without accurate information about how many people are living with the virus, it is difficult for drug and clinical trial developers to invest resources into studying or pursuing drug development or clinical trials for HDV.

Another problem is the many resources of time, money, and labor that are necessary for developing drugs, and preparing and running clinical trials. The development process for a single drug can take anywhere from 5-15 years and a much larger number of drugs fail to complete this process than succeed. Additionally, there needs to be some degree of existing infrastructure in a particular country in order to both support a clinical trial and ultimately to get a drug approved. Unfortunately, this kind of infrastructure is generally already established and easier to navigate in wealthier countries, so these are the countries in which clinical trials are generally held and in which drug approvals tend to happen first. Public health and clinical infrastructure is slowly developing and becoming more prioritized in different parts of the world and hopefully this trend will continue, but for the time being, the locations of clinical trials and approvals for important treatments point to the much larger issues of lack of access to health and healthcare in much of the world, that in turn stem from deep-seated poverty and inequity. Again, as health equity continues to be a focus of the public eye, these trends will hopefully begin to change, paving the way for greater access to healthcare for hepatitis delta, hepatitis B, and countless other health conditions.

What Is Hep Delta Connect’s Role?

 This year, Hep Delta Connect will continue its work to raise the profile of hepatitis delta, both in the United States and around the world. We are committed to building awareness through partnerships with community-based organizations, healthcare providers, and governmental agencies around the world and through dissemination of educational materials and programming. We hope to foster greater engagement of those living with and affected by hepatitis delta globally, more focused advocacy efforts to bring HDV into the spotlight, and increased screening, diagnosis, and management of HDV. We keep our website and social media channels updated regularly with program news and events – make sure to follow us on Facebook, Twitter, and Instagram and check out our website frequently! You are always welcome to connect with us anytime at connect@hepdconnect.org. We look forward to an exciting year of work on HDV!

I Have Hepatitis B. Could I Also Be Infected with Hepatitis D?

By Sierra Pellechio, Hepatitis Delta Connect Coordinator

Hepatitis delta, or hepatitis D, is an aggressive form of hepatitis that can only infect someone who is also infected with hepatitis B.

People can become infected with hepatitis B and hepatitis D from the same exposure, or people who are already infected with hepatitis B can later be infected with hepatitis D. Coinfection can promote more rapid progression to cirrhosis and liver cancer than being infected with hepatitis B alone and will require an altered treatment and management plan. Being aware could save your life!

Hepatitis D can be spread similarly to hepatitis B, through exposure to blood or bodily fluids of an infected person. People with hepatitis B are likely to develop a chronic hepatitis delta coinfection if they are exposed to the virus, making it important for you and your doctor to be aware of the signs of a coinfection.

Cues to suspect a coinfection:

  • You have chronic hepatitis B but are not responding to antiviral treatment, or you have signs of liver damage even though your viral load is low (HBV DNA below 2,000 IU/mL)

Note: Fatty liver disease (caused by obesity) and liver damage from alcohol or environmental toxins should be ruled out as causes of liver damage before testing for hepatitis D.

It is also important for hepatitis B patients who originate from Sub-Saharan Africa, China, Russia, the Middle East, Mongolia, Romania, Georgia, Turkey, Pakistan and the Amazonian River Basin to be tested for hepatitis D, where it is more common. Most of the time, patients do not have any signs or symptoms to let them know they are coinfected, so a simple blood test is the only way to know for sure! Talk to your liver specialist about testing at your next appointment.

Hepatitis Delta Connect is a dedicated program of the Hepatitis B Foundation aimed to provide information and support for those affected by hepatitis D. Please visit our website, www.hepdconnect.org for more information and follow us on Facebook, Twitter and Instagram to stay up to date on the latest hepatitis D news! If you are a patient or provider and have questions or concerns, please email us at connect@hepdconnect.org.

Check out our previous posts about hepatitis D here, here, and here.