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There is a lack of large comparative study on the outcomes of reduced intensity conditioning (RIC) in acute myeloid leukemia (AML) transplantation using fludarabine/busulfan (FB) and fludarabine/melphalan (FM) regimens. Adult AML patients from Center for International Blood and Marrow Transplant Research who received first RIC allo-transplant between 2001 and 2015 were studied. Patients were excluded if they received cord blood or identical twin transplant, total body irradiation in conditioning, or graft-versus-host disease (GVHD) prophylaxis with in vitro T-cell depletion. Primary outcome was overall survival (OS), secondary end points were leukemia-free survival (LFS), nonrelapse mortality (NRM), relapse, and GVHD. Multivariate survival model was used with adjustment for patient, leukemia, and transplant-related factors. A total of 622 patients received FM and 791 received FB RIC. Compared with FB, the FM group had fewer transplant in complete remission (CR), fewer matched sibling donors, and less usage of anti-thymocyte globulin or alemtuzumab. More patients in the FM group received marrow grafts and had transplantation before 2005. OS was significantly lower within the first 3 months posttransplant in the FM group (hazard ratio [HR] = 1.82, P < .001), but was marginally superior beyond 3 months (HR = 0.87, P = .05). LFS was better with FM compared with FB (HR = 0.89, P = .05). NRM was significantly increased in the FM group during the first 3 months of posttransplant (HR = 3.85, P < .001). Long-term relapse was lower with FM (HR = 0.65, P < .001). Analysis restricted to patients with CR showed comparable results. In conclusion, compared with FB, the FM RIC showed a marginally superior long-term OS and LFS and a lower relapse rate. A lower OS early posttransplant within 3 months was largely the result of a higher early NRM.

Allogeneic bone marrow transplantation (BMT) is curative therapy for the treatment of patients with severe aplastic anemia (SAA). However, several conditioning regimens can be used for BMT. We evaluated transplant conditioning regimens for BMT in SAA after HLA-matched sibling and unrelated donor BMT. For recipients of HLA-matched sibling donor transplantation (n = 955), fludarabine (Flu)/cyclophosphamide (Cy)/antithymocyte globulin (ATG) or Cy/ATG led to the best survival. The 5-year probabilities of survival with Flu/Cy/ATG, Cy/ATG, Cy ± Flu, and busulfan/Cy were 91%, 91%, 80%, and 84%, respectively (P = .001). For recipients of 8/8 and 7/8 HLA allele-matched unrelated donor transplantation (n = 409), there were no differences in survival between regimens. The 5-year probabilities of survival with Cy/ATG/total body irradiation 200 cGy, Flu/Cy/ATG/total body irradiation 200 cGy, Flu/Cy/ATG, and Cy/ATG were 77%, 80%, 75%, and 72%, respectively (P = .61). Rabbit-derived ATG compared with equine-derived ATG was associated with a lower risk of grade II to IV acute graft-versus-host disease (GVHD) (hazard ratio [HR], 0.39; P < .001) but not chronic GVHD. Independent of conditioning regimen, survival was lower in patients aged >30 years after HLA-matched sibling (HR, 2.74; P < .001) or unrelated donor (HR, 1.98; P = .001) transplantation. These data support Flu/Cy/ATG and Cy/ATG as optimal regimens for HLA-matched sibling BMT. Although survival after an unrelated donor BMT did not differ between regimens, use of rabbit-derived ATG may be preferred because of lower risks of acute GVHD.

We report graft-versus-host disease (GVHD)-free relapse-free survival (GRFS) (a composite end point of survival without grade III-IV acute GVHD [aGVHD], systemic therapy–requiring chronic GVHD [cGVHD], or relapse) and cGVHD-free relapse-free survival (CRFS) among pediatric patients with acute leukemia (n = 1613) who underwent transplantation with 1 antigen–mismatched (7/8) bone marrow (BM; n = 172) or umbilical cord blood (UCB; n = 1441). Multivariate analysis was performed using Cox proportional hazards models. To account for multiple testing, P < .01 for the donor/graft variable was considered statistically significant. Clinical characteristics were similar between UCB and 7/8 BM recipients, because most had acute lymphoblastic leukemia (62%), 64% received total body irradiation–based conditioning, and 60% received anti-thymocyte globulin or alemtuzumab. Methotrexate-based GVHD prophylaxis was more common with 7/8 BM (79%) than with UCB (15%), in which mycophenolate mofetil was commonly used. The univariate estimates of GRFS and CRFS were 22% (95% confidence interval [CI], 16-29) and 27% (95% CI, 20-34), respectively, with 7/8 BM and 33% (95% CI, 31-36) and 38% (95% CI, 35-40), respectively, with UCB (P < .001). In multivariate analysis, 7/8 BM vs UCB had similar GRFS (hazard ratio [HR], 1.12; 95% CI, 0.87-1.45; P = .39), CRFS (HR, 1.06; 95% CI, 0.82-1.38; P = .66), overall survival (HR, 1.07; 95% CI, 0.80-1.44; P = .66), and relapse (HR, 1.44; 95% CI, 1.03-2.02; P = .03). However, the 7/8 BM group had a significantly higher risk for grade III-IV aGVHD (HR, 1.70; 95% CI, 1.16-2.48; P = .006) compared with the UCB group. UCB and 7/8 BM groups had similar outcomes, as measured by GRFS and CRFS. However, given the higher risk for grade III-IV aGVHD, UCB might be preferred for patients lacking matched donors.

Introduction. There is little information on the effect of donor body mass index (BMI) on mobilization response to Filgrastim (G-CSF), especially in the unrelated donor setting. Obesity has been associated with chronic low-grade inflammation due to chronic activation of the innate immune system. Obesity-induced pro-inflammatory cytokines can interfere with bone marrow SDF1/CXCR4 axis and promote mobilization of progenitor cells leading to persistent leukocytosis and an increase in number of circulating progenitor cells. Given a higher number of circulatory progenitor cells in obese individuals compared to non-obese, a reduced G-CSF dose in obese donors may elicit adequate response, thus reducing the adverse events associated with peripheral blood stem cell (PBSC) collection. The aim of this study is to evaluate the impact of donor BMI on G-CSF mobilized peripheral blood progenitor cell yield in healthy donors. This study also examines whether there is a G-CSF dose threshold above which there is a significant increase in skeletal pain and other acute toxicities from mobilization without an appreciable increase in progenitor cell yield. Methods. The primary outcome was examination of CD34+ per liter of blood processed (x106/L) on Day 5 of G-CSF administration as a measure of collection yield. The secondary outcomes were the incidence of skeletal pain and highest toxicity level across selected body symptoms (fatigue, nausea, anorexia, insomnia, dizziness) at 24 hours after first G-CSF dose, day 1 to 5 of G-CSF administration, 2 days and 1-week post collection. The population studied was domestic unrelated G-CSF mobilized PBSC donors reported to the NMDP/CIBMTR between 2006 and 2016. G-CSF dosing was based on the NMDP weight-based dosing schema rounded to the nearest vial content. Donors were divided into normal, overweight, obese, and morbidly obese categories based on BMI. Multivariate analysis of collection yields between cohorts were done using linear regression analysis. Stepwise variable selection was used to add variables to the model: BMI group and G-CSF dose was forced into the final model as the variables of interest. Pain and acute toxicities at each time point were described using frequencies and compared between groups using chi-squared test or Fisher's exact test after adjusting for donor and baseline characteristics. Results. Examination of 20, 884 PBSC donors mobilized by G-CSF revealed a significant increase in collection yield in obese and morbidly obese compared to normal and overweight donors. Median CD34+ per liter of blood processed (x106/L) on Day 5 of G-CSF was 29.6, 36.4, 40.8 and 42.9 in normal, overweight, obese and morbidly obese donors, respectively (p Figure 1 shows the time course and degree of toxicities in different BMI categories. Obese and morbidly obese were more likely to experience grade 2-4 pain and toxicities compared with normal or overweight in both the peri-collection and early post-donation recovery period but by one week after donation most toxicities abated and there was no difference. Donors with a higher BMI were more likely to experience grade 2 to 4 skeletal pain 24 hours post first G-CSF dose, 2 days post donation and at day 1 to 5 G-CSF administration. In addition, donors with higher BMI were more likely to have grade 2-4 toxicities (fatigue, anorexia, insomnia) at day 1 to 5 of G-CSF and 2 days after collection. However, within each BMI group, incremental increase in G-CSF dose was not associated with greater pain or other toxicities. Conclusions. Our data indicates a correlation between average daily G-CSF dose and CD34+ cell yield in normal and overweight donors. However, in obese and morbidly obese donors, there was no benefit in CD34+ yield with increasing average daily G-CSF dose above 780 mcg and 900 mcg respectively. Therefore, there appears to be a maximum effective G-CSF dose for mobilization in obese and morbidly obese donors where higher doses of G-CSF add no additional benefit and may result in additional complications. Download : Download high-res image (677KB) Download : Download full-size image Disclosures Pulsipher: Novartis: Consultancy, Honoraria, Speakers Bureau; Amgen: Honoraria; Adaptive Biotech: Consultancy, Research Funding; CSL Behring: Consultancy.

Presumably, reduced-intensity/nonmyeloablative conditioning (RIC/NMA) for allogeneic hematopoietic cell transplantation (alloHCT) results in reduced infections compared with myeloablative conditioning (MAC) regimens; however, published evidence is limited. In this Center for International Blood and Marrow Transplant Research study, 1755 patients (aged ≥40 years) with acute myeloid leukemia in first complete remission were evaluated for infections occurring within 100 days after T-cell replete alloHCT. Patients receiving RIC/NMA (n = 777) compared with those receiving MAC (n = 978) were older and underwent transplantation more recently; however, the groups were similar regarding Karnofsky performance score, HCT–comorbidity index, and cytogenetic risk. One or more infections occurred in 1045 (59.5%) patients (MAC, 595 [61%]; RIC/NMA, 450 [58%]; P = .21) by day 100. The median time to initial infection after MAC conditioning occurred earlier (MAC, 15 days [range