Impact Of Female Donor On Allogeneic Stem Cell Transplantation Outcome Of Male Recipient After T-Cell Depletion By Rabbit Antithymocyte Globulin

The female donor/male recipient combination (FM) increases the risks of graft-versus-host disease (GVHD) and non-relapse mortality (NRM) after allogeneic stem cell transplantation (allo-SCT), with a possible deleterious impact on overall survival (OS) [Gahrton G. Best Pract Res Clin Haematol. 2007 Jun;20(2):219-29]. Most patients in these studies received T-cell replete transplants. As a consequence, and because antithymocyte globulin (ATG) reduces the risk of GVHD, the impact of FM in the specific setting of allo-SCT with ATG remains poorly defined.

To explore the impact of FM in the ATG setting, we undertook a retrospective analysis of male adult patients transplanted with rabbit ATG at our center between 01/01/2000 and 12/31/2012. Overall survival and disease-free survival (DFS) were calculated using the Kaplan-Meier estimate, with comparisons by the log-rank test. Cumulative incidences (CI) were used for NRM, relapse (REL), and GVHD in a competing risks setting, NRM being a competing event for REL, and death for GVHD. The Gray test was used to compare CI curves. For multivariate analysis, the variables with p value < 0.1 were entered into a Fine-Gray model where the least significant variables were excluded in sequential fashion until all remaining factors were significant at the p=0.05 level. The following variables were considered: recipient age (≥ vs < 56 years, median age), female donor (FD) vs male donor (MD), matched related (MRD) vs matched unrelated (MUD) donor, peripheral blood (PB) vs bone marrow (BM) graft, GVHD prophylaxis with cyclosporine (CsA)+metho vs others, myeloablative (MAC) vs reduced-intensity conditioning (RIC) regimen, CMV-seropositive vs seronegative recipient, early (CR1 or PR1 or chronic phase or untreated) vs advanced disease. Steroid-refractory (SR) acute (a) GVHD was defined as aGVHD progressing after 3 days of treatment, or unchanged after 7 days, or in incomplete response after 14 days. MUD were matched at the allele level for HLA-A, B, C, DRB1, DQB1.

Two hundred and twelve male patients were identified and included in the present study. The median age was 56 years (18-67). Diseases were AML (n=61), ALL (n=16), NHL (n=36), Hodgkin's disease (n=10), myeloma (n=37), MDS (n=26), aplastic anemia (n=7), CLL (n=11), CML (n=1), and MPS (n=7). Status at transplant were CR1 or PR1 or chronic phase (n=74), > CR1 or PR1 (n=83), refractory (n=34), or untreated (n=21). Conditioning regimens were RIC (n=195) or MAC (n=17). Donors were MRD (n=110) or MUD (n=102). Eighty-eight patients were transplanted with a FD. Source of stem cells were PB (n=193), BM (n=18), missing data (n=1). Prophylaxis of GVHD consisted of CsA+metho for 84 patients.

The median follow-up was 42 months (5-149). In univariate analysis, the 3-year OS and DFS in FD vs MD groups were 48% ± 6% vs 56% ± 5% (p=0.3) and 42% ± 5% vs 50% ± 5% (p=0.4), respectively. The 3-year NRM and REL in the same groups were 25% ± 5% vs 19.6% ± 4% (p=0.4) and 30% ± 5% vs 31% ± 4% (p=0.9), respectively. The CI of aGVHD II-IV, aGVHD III-IV, SR aGVHD, and extensive chronic GVHD in FD vs MD groups were 37.5% ± 5% vs 33% ± 4% (p=0.5), 22.7% ± 4% vs 17% ± 3% (p=0.3), 17.2% ± 4% vs 8.3% ± 3% (p=0.049), and 20% ± 4% vs 22.5% ± 4% (p=0.9), respectively. Other variables considered in univariate analysis for SR aGVHD were recipient age (p=0.9), recipient CMV status (p=0.7), disease status (p=0.9), RIC vs MAC (p=0.16), MRD vs MUD (p=0.09), PB vs BM graft (p=0.4), and GVHD prophylaxis (p=0.2). In multivariate analysis, the risk factors for SR aGVHD were FD (HR=3.1, 95%CI: 1.2-7.9, p=0.01) and MUD (HR=2.9, 95%CI: 1.1-7.1, p=0.02). The CI of SR aGVHD were 32.3% ± 9.7% in the FD + MUD group (n=29), 9.7% ± 3.8% in the MD + MUD group (n=73), 10.7% ± 4.1% in the FD + MRD group (n=59), and 6.5% ± 3.7% in the MD + MRD group (n=51); p=0.004.

We conclude that FD was an independent risk factor for SR aGVHD after allo-SCT with rabbit ATG in male adult patients mostly transplanted with PB after RIC. There was no impact of FD on aGVHD II-IV or III-IV, chronic GVHD, NRM, REL or survival. Finally, the absence of impact of FD on NRM and survival should be interpreted with caution given the retrospective design of the study and because we cannot exclude a possible limiting effect of an insufficient number of patients.