A real-world analysis of bulevirtide found a safety and efficacy profile similar to what was seen in earlier clinical trials in the treatment of hepatitis delta virus (HDV) infection.
HDV can only infect patients already carrying hepatitis B virus (HBV), but it causes the most severe form of viral hepatitis as it can progress to cirrhosis within 5 years and to hepatocellular carcinoma within 10 years.
Bulevirtide is a first-in-class medication that mimics the hepatitis B surface antigen, binding to its receptor on hepatocytes and preventing HDV viral particles from binding to it. The drug received conditional marketing approval by the European Medicines Agency in 2020 and has received a breakthrough therapy designation from the U.S. Food and Drug Administration.
The study was presented at the annual meeting of the American Association for the Study of Liver Diseases by Victor De Ledinghen, PhD, who is a professor of hepatology and head of the hepatology and liver transplantation unit at Bordeaux (France) University Hospital.
The early-access program launched after the French National Agency for Medicines and Health Products approved bulevirtide in 2019. It was made available to patients with compensated cirrhosis or severe liver fibrosis (F3) or patients with F2 fibrosis and alanine amino transferase levels more than twice the upper limit of normal for 6 months or more. Patients received bulevirtide alone (n = 77) or in combination with peg-interferon (n = 68), as determined by their physician.
The researchers defined virologic efficacy as HDV RNA levels being undetectable, or decreased by at least 2 log10 from baseline. They defined biochemical efficacy as ALT levels below 40 IU/L.
A per-protocol analysis included all patients in the bulevirtide group, but excluded 12 from the combination group who discontinued peg-interferon (n = 56). Nineteen patients in bulevirtide group had a treatment modification, and seven discontinued treatment. Five in the combination group had a treatment modification, and 14 stopped treatment. At 12 months, there was a greater decline in median log10 IU/mL in the combination group (–5.65 versus –3.64), though the study was not powered to compare the two. At 12 months, the combination group had 93.9% virologic efficacy, compared with 68.3% in the bulevirtide group.
The two groups had similar mean ALT levels at 12 months (48.91 and 48.03 IU/mL, respectively), with more patients in the bulevirtide group having normal ALT levels (<40 IU/L; 48.8% versus 36.4%). At 12 months, 39.0% of the bulevirtide group and 30.3% of the combination group had a combined response, defined as either undetectable HDV RNA or ≥2 log10 from baseline plus normal ALT levels.
Twenty-nine patients in the bulevirtide group had an adverse event, compared with 43 in the combination group. The two groups were similar in the frequency of grade 3-4 adverse events (7 versus 6), discontinuation due to adverse events (2 versus 3), deaths (0 in both), injection-site reactions (2 in both), liver-related adverse events (4 versus 2), and elevated bile acid (76 versus 68).
During the Q&A period following the presentation, Dr. De Ledinghen was asked if he has a preferred regimen for HDV patients. “I think it depends on the tolerance of peg-interferon because of all the side effects with this drug. I think we need to have predictive factors of virological response with or without interferon. At this time, I don’t have a preference, but I think at this time we need to work on predictive factors associated with virologic response,” he said.
The EMA’s conditional bulevirtide approval hinged on results from phase 2 clinical trials, while the phase 3 clinical studies are ongoing. “This was a very unusual step for the EMA to provide what is similar to emergency use approval while the phase 3 clinical trials are still ongoing,” said Anna Lok, MD, who was asked to comment on the study. Dr. Lok is a professor of internal medicine, director of clinical hepatology, and assistant dean for clinical research at the University of Michigan, Ann Arbor.
She noted that the phase 2 studies indicated that the combination with peg-interferon seems to have an additive effect on HDV suppression, while monotherapy with bulevirtide has a greater effect on normalizing ALT levels. The real-world experience confirms these findings.
But the real-world data revealed some concerns. “What really worried me is the large number of patients who required dose modifications or discontinuations, and that seems to be the case in both treatment groups. They didn’t really go into a lot of details [about] why patients needed treatment modifications, but one has to assume that this is due to side effects,” said Dr. Lok.
She also noted that the per-protocol analysis, instead of an intention-to-treat analysis, is a weakness of the study. Additionally, over time, the number of patients analyzed decreased – as many as 40% of patients didn’t have test results at month 12. “It makes you wonder what happened to those patients. Many probably didn’t respond, in which case your overall response rate will be far lower,” said Dr. Lok.
The study was funded by Gilead. Dr. De Ledinghen has financial relationships with Gilead, AbbVie, Echosens, Hologic, Intercept Pharma, Tillotts, Orphalan, Alfasigma, Bristol Myers Squibb, and Siemens Healthineers. Dr. Lok has no relevant financial disclosures.