Non-Myeloablative Allogeneic Bone Marrow Transplantation for Hematologic Malignancies Using Haploidentical Donors: A Phase I Trial of Pre-Transplant Cyclophosphamide

OBJECTIVES:

• Determine the minimum effective dose of pretransplant cyclophosphamide to induce engraftment of haploidentical allogeneic bone marrow without the use of myeloablative conditioning in patients with hematologic malignancies.
• Determine the incidence and severity of graft versus host disease and nonhematologic toxicities with this treatment regimen in these patients.
• Correlate the pretreatment phenotypic and functional immunologic characteristics in these patients in relation to risk of graft rejection with this treatment regimen.

OUTLINE: This is a dose-escalation study of cyclophosphamide.

Patients receive fludarabine IV over 1 hour on days -6 to -2; cyclophosphamide IV over 1 hour on days -6, -5, and 3; total body irradiation on day -1; and allogeneic bone marrow transplantation on day 0. Patients also receive tacrolimus IV or orally twice a day on days 4-50; oral mycophenolate mofetil on days 4-35; and filgrastim (G-CSF) subcutaneously or IV starting on day 4 and continuing until blood counts recover.

Cohorts of 3-6 patients receive escalating doses of cyclophosphamide until the minimum effective dose necessary to induce chimerism without unacceptable toxicity in these patients is determined.