The biopharmaceutical company Bluejay Therapeutics is conducting clinical trials of a novel therapeutic candidate, Brelovitug (BJT-778), developed for the treatment of chronic hepatitis delta (hepatitis D). In 2025, two global Phase III clinical studies — AZURE-1 and AZURE-2 — were launched to evaluate the efficacy and safety of the drug.

Brelovitug is an IgG1 monoclonal antibody targeting the hepatitis B surface antigen (HBsAg).By binding to HBsAg, it blocks the spread of hepatitis B and hepatitis D viruses and helps reduce circulating antigen levels in patients. In January 2025, the Food and Drug Administration (FDA) granted Brelovitug Breakthrough Therapy Designation, indicating that the therapy demonstrates substantial potential advantages over existing treatments.

Additionally, the European Medicines Agency (EMA) awarded Brelovitug PRIME (PRIority MEdicines) and Orphan Drug Designation, underscoring its importance for addressing rare and severe diseases.

AZURE-1 Study (NCT06907290)

  • Type: International, randomized, open-label, Phase 2b/3.

  • Objective: To assess the efficacy and safety of Brelovitug compared with delayed treatment in adults with chronic HDV infection.

  • Estimated enrollment: ~150 participants.

  • Start date: March 2025.

  • Estimated completion: June 2028.

  • Participating countries: United States, Bulgaria, Georgia, Israel, Ukraine, Moldova.

Design:

Participants are randomized into three groups: two receive Brelovitug in different dosing regimens (once weekly or once every four weeks), while the third group undergoes 24 weeks of delayed treatment before starting active therapy.

The primary endpoint is achieving a combined response — undetectable HDV RNA and normalization of ALT levels.

AZURE-2 Study (NCT07200908)

  • Type: International, randomized, Phase 3.

  • Objective: Direct comparison of Brelovitug versus Bulevirtide (Hepcludex®), currently the only approved therapy for hepatitis D in Europe.

  • Estimated enrollment: ~172 participants.

  • Start date: September–October 2025.

  • Participating regions: European clinical sites (full list pending).

Design:

Participants are randomized in a 3:1 ratio.

One group receives Brelovitug 300 mg weekly for 96 weeks, while the comparator group receives Bulevirtide 2 mg daily for 48 weeks, followed by a switch to Brelovitug for another 48 weeks.

The primary endpoint is a combined virologic and biochemical response at week 48 — undetectable HDV RNA and ALT normalization. Preliminary data from earlier clinical stages suggest that Brelovitug demonstrates a high rate of virologic response and a favorable safety profile. If the ongoing studies confirm these findings, Brelovitug could become the first alternative therapy for HDV infection after Bulevirtide, expanding treatment options for patients with this severe form of viral hepatitis.