Busulfan-based myeloablative conditioning regimens for haploidentical transplantation in high-risk acute leukemias and myelodysplastic syndromes.

BACKGROUND

High-risk acute leukemia (AL) and myelodysplastic syndrome (MDS) remain a therapeutic challenge. Unmanipulated haploidentical-related donor transplantation based on a myeloablative conditioning regimen (HAPLO-MAC) and post-transplant cyclophosphamide (PT-Cy) as prophylaxis against graft vs host disease (GvHD) is now a promising rescue strategy that could become universally available.

OBJECTIVE

To evaluate the results of HAPLO-MAC with PT-Cy in patients with AL and MDS reported to the Haploidentical Transplantation Subcommittee of the Spanish Group for Hematopoietic Transplantation (GETH).

PATIENTS AND METHODS

We report our multicenter experience using an IV busulfan-based HAPLO-MAC regimen and PT-Cy for treatment of 65 adults with high-risk AL and MDS.

RESULTS

Engraftment was recorded in 64 patients (98.5%), with a median time to neutrophil and platelet recovery of 16 and 27 days, respectively. The cumulative incidence of grade II-IV acute GvHD and chronic GvHD was 28.6% and 27.5%, respectively. After a median follow-up of 31 months for survivors, the cumulative incidence of non-relapse mortality and relapse at 2 years was 18.8% and 25%, respectively. Estimated 30-month event-free survival and overall survival were 56% and 54.5%, respectively.

CONCLUSION

HAPLO-MAC comprising an IV busulfan-based conditioning regimen enabled long-term disease control with acceptable toxicity in high-risk AL and MDS.