Comparison between horse and rabbit antithymocyte globulin as first-line treatment for patients with severe aplastic anemia: a single-center retrospective study.

The best antithymocyte globulin preparation for first-line immune suppression in patients with severe aplastic anemia is still not clear. The aim of this study was to compare hematological response and overall survival in patients submitted to horse or rabbit antithymocyte globulin as first-line treatment for severe aplastic anemia. We retrospectively compared 71 consecutive patients with severe aplastic anemia, classified according to the antithymocyte globulin preparation. Analyses included variables related to patients and to immune suppression. Forty two patients (59.1%) received horse and 29 (40.9%) rabbit antithymocyte globulin. Response rates were higher at 6 months in patients submitted to horse in comparison to rabbit antithymocyte globulin (59.5% versus 34.5% respectively, p = 0.05). Median time to response was similar between the two groups (99 versus 88.5 days, respectively, for horse and rabbit antithymocyte globulin; p = 0.98). Overall survival at 2 years was significantly higher in patients submitted to horse in comparison to rabbit antithymocyte globulin (78.4% versus 55.4%, p = 0.03). Post-treatment response was strongly associated with survival at 2 years (97% in responders versus 41.2% in non-responders, p < 0.001). Use of rabbit antithymocyte globulin was an independent predictor of death (odds ratio 2.5; 95% confidence interval 1.03-6.04; p = 0.04). Rabbit antithymocyte globulin was associated with a significant and prolonged lymphopenia in comparison with horse antithymocyte globulin. Our data suggest the superiority of horse over rabbit antithymocyte globulin as first-line treatment for severe aplastic anemia, both regarding hematological response and survival.

High CD8+ lymphocyte dose in the autograft predicts early absolute lymphocyte count recovery after peripheral hematopoietic stem cell transplantation.

Early lymphocyte recovery (ELR) after autologous peripheral hematopoietic stem cell transplantation (ASCT) is an independent predictor for survival in patients with hematological and non-hematological cancers. Sixty-five ASCT for hematological cancers were retrospectively analyzed to identify the factors associated with ELR and to assess the impact of different mobilization regimens on the pre-collection absolute lymphocyte count (ALC). The CD8+ lymphocyte dose in the autograft and the pre-mobilization ALC were independently associated with ELR (P < 0.001 and P = 0.008, respectively). CD8+ lymphocyte doses higher than 0.1 x 10(9)/kg were strongly associated with ELR [P < 0.001, odds ratio 25.22, 95% confidence interval (CI) 4.98-127.69] and this cutoff may be used to predict ELR (P = 0.001, area under the curve 0.75, 95% CI 0.62-0.88). Mobilization with granulocyte colony-stimulating factor (G-CSF) alone, the pre-collection ALC and the number of apheresis sessions were independently associated with the CD8+ lymphocyte dose (P = 0.04, P = 0.001, and P < 0.001, respectively). The number of aphereses was the variable with the strongest correlation to the CD8+ lymphocyte dose (r(s) = 0.68, P < 0.001). Median pre-mobilization ALC was higher than pre-collection ALC in the subgroup of patients without ELR mobilized with chemotherapy followed by G-CSF (1090 vs. 758 lymphocytes/microL; P < 0.001). This reduction was not significant in the subgroup with ELR mobilized with chemotherapy plus G-CSF (1920 vs. 1539/microL, respectively; P = 0.23). These results suggest that the CD8+ lymphocyte dose in the autograft is critical for ELR after ASCT and also demonstrates that mobilization with chemotherapy followed by G-CSF significantly decreases the pre-collection ALC, especially in patients with low pre-mobilization ALC.