Fludarabine/i.v. BU conditioning regimen: myeloablative, reduced intensity or both?

Area of Science:

• Hematology
• Oncology
• Transplant Immunology

Background:

• Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative option for various hematologic malignancies.
• Myeloablative conditioning regimens are crucial for graft engraftment and disease control but are associated with significant toxicity.
• The fludarabine and intravenous busulfan (FluBU) regimen is a myeloablative conditioning option with a potentially favorable toxicity profile.

Purpose of the Study:

• To evaluate the efficacy and safety of the FluBU conditioning regimen in adult patients with myeloid or lymphoid malignancies undergoing allogeneic HSCT.
• To assess overall survival (OS), event-free survival (EFS), treatment-related mortality (TRM), and relapse rates in standard- and high-risk patients.
• To compare the outcomes of the FluBU regimen with other standard myeloablative conditioning regimens.

Main Methods:

• A cohort of 36 adult patients with myeloid or lymphoid malignancies received allogeneic HSCT after FluBU conditioning.
• Patients were stratified into standard-risk (n=10) and high-risk (n=26) groups.
• Graft sources included peripheral blood (n=28) and marrow (n=8) from HLA-matched related or unrelated donors.
• Rabbit-antithymocyte globulin was administered to 21 patients.

Main Results:

• Overall survival rates were 80% for standard-risk and 35% for high-risk patients.
• Event-free survival rates were 70% for standard-risk and 31% for high-risk patients.
• Treatment-related mortality was 10% in standard-risk and 19% in high-risk patients.
• Post-transplant relapse rates were 20% in standard-risk and 46% in high-risk patients.
• Acute GVHD (grade II-IV) occurred in 19% of patients, and chronic GVHD in 37% of evaluable patients.

Conclusions:

• The FluBU conditioning regimen demonstrated limited hematologic and extrahematologic toxicity.
• The regimen exhibited antitumor activity comparable to other standard myeloablative regimens.
• FluBU is a viable myeloablative conditioning option for allogeneic HSCT in patients with myeloid or lymphoid malignancies, particularly those at standard risk.