Stem Cell Transplantation |
* Unite de Transplantation et de Therapie Cellulaire (UTTC), Institut Paoli-Calmettes, Marseille, France
° Université de la Méditerranée, Faculté de Médecine, Marseille, France;
# INSERM, UMR 599, Marseille, France;
@ Laboratoire dImmunologie, Hopital Saint-Eloi, CHU de Montpellier, Montpellier, France;
^ Département dOncologie Médicale, Institut Paoli-Calmettes, Marseille, France DB and JFE share senior authorship
Correspondence: Mohamad Mohty, M.D., Ph.D., Institut Paoli-Calmettes, 232 Bd. Ste Marguerite, F-13273 Marseille Cedex 09, France. Phone: international +33 491 223823; Fax: international +33 491 223579. E-Mail: mohtym{at}marseille.fnclcc.fr
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Initial mixed donor/host chimerism has usually been observed in most patients after reduced-intensity conditioning allogeneic stem cell transplantation (RIC-allo-SCT). This retrospective single center study investigated the impact of different factors on the establishment of full donor CD3+ T cell chimerism (TCC) in a series of 102 patients receiving RIC allo-SCT. Only patients who were alive at the third month after RIC-allo-SCT were included. All donors were HLA-A-, HLA-B-, and HLA-DR-identical siblings. Eligibility criteria for RIC allo-SCT are detailed elsewhere.1 The RIC regimen included either fludarabine, oral busulfan and low dose anti-thymocyte globulin (ATG 2.5 or 5 mg/kg total dose; Thymoglobulin, Genzyme, Lyon, France),1 or fludarabine (150 mg/m2 total dose) and low dose irradiation [TBI 2 Gy, or total lymphoid irradiation (TLI), 1.5 Gy total dose] with or without busulfan. Busulfan total dose was 8 mg/kg when ATG was used and 4 mg/kg with TLI. Choice of the RIC regimen type was not based on disease category. Supportive care has been previously reported and was similar during the whole study period.2 Graft-vs.-host disease (GVHD) prophylaxis was given with cyclosporine A (CSA) alone or with CSA and mycophenolate mofetil (MMF). According to protocols, MMF was discontinued at day 35 after allo-SCT. CSA tapering was started between day 80 and 100 if no GVHD appeared. All patients received peripheral blood stem cells mobilized with G-CSF.
TCC (on sorted peripheral blood T lymphocytes) was serially assessed approximately 30, 60 and 90 days after allo-SCT as previously described.3 Mixed T-cell chimerism was defined as between 5 and 94% recipient cells, and full chimerism was defined as the presence of more than 95% donor cells.4 Patients and RIC-allo-SCT characteristics are detailed in Table 1. Kinetics of full donor TCC are shown in Figure 1A. In univariate analysis, none of the patients graft, RIC type, or disease characteristics were predictive of establishment of an early full donor TCC at day 30. However, the 31 patients who achieved this experienced a higher incidence of grade 2–4 acute GVHD compared to the 71 patients who were still in mixed TCC at day 30 (cumulative incidence, 61% vs. 35%; p=0.01; Figure 1B). Univariate analysis of predictive factors for full donor TCC at day 90 is shown in Table 1. Diagnosis category (Figure 1C), the RIC regimen type (Figure 1D), a female donor, CD34+ stem cell dose, and CD4+ T cell dose infused with the graft, were significantly or had a trend towards significant association with full donor TCC at day 90. In the multivariate analysis, a diagnosis other than a myeloid malignancy, was predictive of full TCC at day 90 (p=0.007; OR=3.82;95%CI,1.4–10.1). The delayed full donor TCC in patients with myeloid malignancies (AML, CML, MDS) resulted in a poorer PFS (p=0.06; Figure 1E). This was also confirmed when analysis was restricted to the 24 patients with AML (p=0.017). Interestingly, there were no significant differences between disease risk factors in the AML patients sub-group who achieved full donor TCC when compared to the other sub-group. This poorer PFS for myeloid malignancies was due to a higher incidence of relapse (6 relapses/15 patients in mixed TCC; 40%) compared to none in the 26 patients in full TCC (p=0.002; Figure 1F).
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Table 1. Univariate analysis of risk factors for full donor T-cell chimerism at day 90 after transplantation
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Figure 1. Kinetics of T-cell chimerism (TCC) after RIC allo-SCT. (A)% of patients achieving full donor TCC in the first three months after allo-SCT. Patients included in this study were assessed at all time points. (B) Cumulative incidence of grade 2–4 acute GVHD according to the TCC status at the end of the first month after allo-SCT. (C) Kinetics of TCC in the first three months after allo-SCT according to disease category. (D) Kinetics of TCC in the first three months after allo-SCT according to the RIC regimen type. (E) Progression-free survival in patients with myeloid malignancies according to TCC status at the end of the third month after allo-SCT. (F) Cumulative incidence of relapse in patients with myeloid malignancies (AML, CML, MDS) according to TCC status at the end of the third month after allo-SCT.
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