ABSTRACT
Cyclophosphamide (Cy) is a potent immunosuppressive agent that is selectively toxic to lymphocytes proliferating in response to recent antigen stimulation. In animal models, both graft rejection and GVHD after histoincompatible BMT can be inhibited by the posttransplantation administration of high-dose Cy. Therefore, a phase I clinical trial was undertaken to determine the minimal conditioning, including posttransplantation Cy, that permits the stable engraftment of partially HLA-mismatched marrow (up to 3 HLA antigens) from first-degree relatives. Thirteen patients (median age, 53 years) with high-risk hematologic malignancies received conditioning with fludarabine, 30 mg/m2 per day from days -6 to -2, and TBI, 2 Gy on day -1. All patients received Cy, 50 mg/kg on day 3, mycophenolate mofetil from day 4 to day 35, and tacrolimus from day 4 to day > or = 50. Three patients in cohort 1 received no additional conditioning, and 2 experienced graft rejection. Ten patients in cohort 2 received identical conditioning with the addition of Cy 14.5 mg/kg on days -6 and -5. Sustained donor cell engraftment occurred in 8 of these patients, with a median time to absolute neutrophil count > 500/microL of 15 days (range, 13-16 days) and to unsupported platelet count > 20,000/microL of 14 days (range, 0-26 days). All patients with engraftment achieved > or = 95% donor chimerism within 60 days of transplantation. Two patients with myelodysplastic syndrome rejected their grafts but experienced autologous neutrophil recovery at 24 and 44 days. Histologic acute GVHD developed in 6 patients (grade II in 3 patients, grade III in 3 patients) at a median of 99 days (range, 38-143 days) after transplantation and was fatal in 1 patient. At a median follow-up of 191 days (range, 124-423 days), 6 of 10 patients in cohort 2 were alive, and 5 were in complete remission of their disease, including both patients with graft rejection. These data demonstrate that partially HLA-mismatched bone marrow can engraft rapidly and stably after nonmyeloablative conditioning that includes posttransplantation Cy. Clinically significant antitumor responses occur, even among patients who reject their donor grafts.
Subject(s)
Bone Marrow Transplantation/methods , Cyclophosphamide/administration & dosage , Histocompatibility , Immunosuppressive Agents/administration & dosage , Transplantation Conditioning/methods , Adolescent , Adult , Aged , Bone Marrow Transplantation/immunology , Child , Child, Preschool , Female , Graft Survival , Hematologic Neoplasms/mortality , Hematologic Neoplasms/therapy , Histocompatibility/genetics , Histocompatibility/immunology , Histocompatibility Testing/methods , Humans , Infant , Male , Middle Aged , Nuclear Family , Transplantation, Homologous/immunology , Transplantation, Homologous/methods , Treatment OutcomeABSTRACT
BACKGROUND: T-cell depletion of allografts markedly reduces the incidence of GvHD following BMT. The approach taken at our Center has utilized the physical separation method of counterflow centrifugal elutriation (CCE), augmented by recovery of stem cells from lymphocyte-rich fractions by immunoaffinity selection of CD34(+) stem cells. We wanted to compare the performance characteristics of three commercially available selection devices, as well as the clinical outcomes of patients who received allografts engineered by the different devices. METHODS: BM allografts were prepared for patients undergoing BMT for hematologic malignancies. BM cells were separated into lymphocyte-rich and lymphocyte-depleted fractions using CCE, followed by recovery of CD34(+) cells from the lymphocyte-rich fraction using one of three immunoselection devices [CellPro CEPRATE, Nexell Isolex 300i (software version 2.5) and AmCell CliniMACS]. Allografts consisted of the lymphocyte-depleted fraction plus the CD34-selected fraction. RESULTS: Yields of CD34(+) cells were comparable for the three devices. However, there were significant differences in purity (CEPRATE < Isolex 300i < CliniMACS) and time from start of fractionation to infusion (CEPRATE < CliniMACS < Isolex 300i). More technical problems were encountered with the Isolex 300i device. Allograft compositions were comparable. Transplant outcomes (engraftment and incidence of GvHD) also were comparable. DISCUSSION: Qualitatively and quantitatively, allografts prepared with the CEPRATE, Isolex 300i (v 2.5) and CliniMACS devices should be considered comparable for use in this setting and probably also for direct T-cell depletion of BM.
