Bluejay Therapeutics' brelovitug (BJT-778) has been granted Breakthrough Therapy designation by the U.S. Food and Drug Administration (FDA) for the treatment of chronic hepatitis delta (CHD). This designation aims to accelerate the development and review of brelovitug, a much-needed therapy for this aggressive form of viral hepatitis, which currently lacks approved treatments in the United States.
Keting Chu, M.D., Ph.D., Founder and Chief Executive Officer of Bluejay Therapeutics, stated, "Chronic hepatitis delta is the most aggressive form of viral hepatitis and the lack of approved treatments in the United States creates a major unmet need for patients. Breakthrough Therapy designation recognizes the potential of brelovitug to transform the lives of people living with CHD. We look forward to initiating a global pivotal trial as soon as possible to meet our goal of improving patients' lives."
Mechanism of Action
Brelovitug is a high-potency, fully human immunoglobulin G1 (IgG1) monoclonal antibody (mAb) that targets the surface antigen (HBsAg) of the hepatitis B virus. By targeting HBsAg, brelovitug is designed to neutralize and remove both hepatitis B and hepatitis D virions, as well as deplete HBsAg-containing subviral particles. This dual action makes it a potentially safe and highly efficacious treatment for CHD.
Furthermore, brelovitug has demonstrated immunomodulatory functions in patients with chronic hepatitis B (CHB), potentially aiding in the reconstitution of antiviral immunity and contributing to a functional cure for CHB when combined with other agents.
Clinical Trial Data
Brelovitug is currently being evaluated in a Phase 1/2a clinical trial involving healthy volunteers, individuals with chronic hepatitis B infections, and those with chronic hepatitis B and D co-infections. Preliminary data from the Phase 2 trial, presented in late 2024, demonstrated promising results.
Specifically, 100% of patients across all dose groups achieved a virological response, defined as blood hepatitis D virus levels below the limit of detection or a significant drop from baseline, after up to 44 weeks. Additionally, approximately 40%-50% of patients in each group had no detectable levels of the virus, and 78% of participants achieved a virological response along with normalization of alanine aminotransferase (ALT) levels, an indicator of liver damage.
The Phase 2 study for CHD assigned participants with quantifiable hepatitis D virus (HDV) RNA and hepatitis B virus (HBV) suppressed on nucleos(t)ides to one of three doses of BJT-778: 300 mg weekly (n = 18); 600 mg every week for 12 weeks, then every 2 weeks (n = 11); or 900 mg every 4 weeks after a loading dose administered at week 2 (n = 18).
Key endpoints included safety and tolerability; virologic response, defined as ≥2 log10 HDV RNA IU/mL reduction from baseline or HDV RNA target not detected (TND); ALT normalization in participants with abnormal ALT at baseline; and a combined response of virologic response plus ALT normalization.
Regulatory Status and Future Plans
In addition to the Breakthrough Therapy designation in the US, brelovitug has also received Orphan Drug and PRIME designations from the European Medicines Agency (EMA). These designations provide incentives for companies developing treatments for rare diseases and aim to expedite the development of therapies that address unmet medical needs.
Bluejay Therapeutics is planning to share 48-week data from all three dosing regimens in the second half of 2025 and intends to initiate a global pivotal trial to further assess the efficacy and safety of brelovitug in patients with chronic hepatitis delta.
