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1.
Finding a balance in reduced toxicity hematopoietic stem cell transplantation for thalassemia: role of infused CD3+ cell count and immunosuppression
Meissner, B., Lang, P., Bader, P., Hoenig, M., Müller, I., Meisel, R., Greil, J., Sauer, M. G., Metzler, M., Corbacioglu, S., et al
Bone marrow transplantation. 2024
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Full text
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Editor's Choice
Abstract
We performed a retrospective analysis on 124 patients with transfusion-dependent thalassemia who were registered in the German pediatric registry for stem cell transplantation. All patients underwent first allogeneic hematopoietic stem cell transplantation (HSCT) between 2011 and 2020 and belonged mainly to Pesaro risk class 1-2. Four-year overall (OS) and thalassemia-free survival (TFS) were 94.5% ± 2.9% and 88.0% ± 3.4% after treosulfan-fludarabine-thiotepa- and 96.9% ± 3.1% (P = 0.763) and 96.9% ± 3.1% (P = 0.155) after busulfan-fludarabine-based conditioning. Mixed chimerism below 75% occurred predominantly in treosulfan-based regimens (27.5% versus 6.2%). OS and TFS did not differ significantly between matched sibling, other matched family and matched unrelated donor (UD) HSCTs (OS: 100.0%, 100.0%, 96.3% ± 3.6%; TFS: 96.5% ± 2.4%, 90.0% ± 9.5%, 88.9% ± 6.0%). However, mismatched UD-HSCTs performed less favorable (OS: 84.7% ± 7.3% (P = 0.029); TFS: 79.9% ± 7.4% (P = 0.082)). We generated a scoring system reflecting the risk to develop mixed chimerism in our cohort. The main risk-reducing factors were a high CD3+ cell count (≥6 × 10(7)/kg) in the graft, busulfan-conditioning, pre-conditioning therapy and low-targeted ciclosporin A trough levels. Acute GvHD grade III-IV in treosulfan-based concepts predominantly occurred in patients with UD and reduced GvHD prophylaxis but not in the context of high CD3+ cell doses. Taken together, this information might be used to develop more risk-adapted HSCT regimens for thalassemia patients.
PICO Summary
Population
Children and young adults with transfusion-dependent thalassemia who underwent first allogeneic transplant between 2011 and 2020 and were registered in the German pediatric registry for stem cell transplantation. (n=124)
Intervention
Treosulfan-fludarabine-thiotepa based conditioning (n=92)
Comparison
Busulfan-fludarabine-based conditioning (n=32)
Outcome
Four-year overall (OS) and thalassemia-free survival (TFS) were 94.5% ± 2.9% and 88.0% ± 3.4% after treosulfan-fludarabine-thiotepa- and 96.9% ± 3.1% and 96.9% ± 3.1% after busulfan-fludarabine-based conditioning. Mixed chimerism below 75% occurred predominantly in treosulfan-based regimens (27.5% versus 6.2%). OS and TFS did not differ significantly between matched sibling, other matched family and matched unrelated donor (UD) HSCTs (OS: 100.0%, 100.0%, 96.3% ± 3.6%; TFS: 96.5% ± 2.4%, 90.0% ± 9.5%, 88.9% ± 6.0%). However, mismatched UD-HSCTs performed less favorable (OS: 84.7% ± 7.3%; TFS: 79.9% ± 7.4%). We generated a scoring system reflecting the risk to develop mixed chimerism in our cohort. The main risk-reducing factors were a high CD3+ cell count (≥6 × 10(7)/kg) in the graft, busulfan-conditioning, pre-conditioning therapy and low-targeted ciclosporin A trough levels. Acute GvHD grade III-IV in treosulfan-based concepts predominantly occurred in patients with UD and reduced GvHD prophylaxis but not in the context of high CD3+ cell doses.
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2.
Reduced-intensity allogenic transplantation for children and adolescents with Philadelphia chromosome-positive acute lymphoblastic leukemia
Ishida, H., Arakawa, Y., Hasegawa, D., Usami, I., Hashii, Y., Arai, Y., Nishiwaki, S., Keino, D., Kato, K., Sato, M., et al
Annals of hematology. 2023
Abstract
Survival rates of patients with Philadelphia chromosome-positive ALL (Ph+ALL) have improved considerably with the introduction of tyrosine kinase inhibitors (TKI); however, hematopoietic stem cell transplantation (HSCT) continues to play an important role. Reduced-intensity conditioning (RIC) regimens have been widely applied particularly for older patients, but their validity for children and adolescents with Ph+ALL has not been investigated. In this study, data from patients receiving HSCT for de novo Ph+ALL in first or second remission at ages younger than 25 years and with a history of pre-HSCT TKI therapy were retrospectively collected through the nationwide registry in Japan. In 265 patients who received myeloablative conditioning (MAC) and 33 patients receiving RIC, 5-year leukemia-free survival (LFS) rates were 67.3% and 79.8%, respectively (p = 0.142). Multivariate analysis of LFS, focusing on patients with good performance status, identified RIC as a significant prognostic factor for LFS (hazard ratio 0.32, p = 0.032), as well as older age, higher leukocyte count at diagnosis, and disease with additional chromosomal abnormalities. These trends were similar when we focused on patients who received prophylactic post-HSCT TKI treatment, as 5-year LFS was 81.0% for MAC and 84.4% for RIC (p = 0.748). In summary, HSCT with RIC regimen showed at least comparable LFS to HSCT with MAC regimen, and RIC was an independent favorable prognostic factor on multivariate analysis adjusting potential prognostic factors. While patient numbers were limited, our data suggest that RIC may be safely applied in this group, particularly combined with prophylactic post-HSCT TKI maintenance therapy.
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Autologous versus allogeneic hematopoietic cell transplantation for older patients with acute lymphoblastic leukemia. An analysis from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation
Giebel, S., Labopin, M., Houhou, M., Caillot, D., Finke, J., Blaise, D., Fegueux, N., Ethell, M., Cornelissen, J. J., Forcade, E., et al
Bone marrow transplantation. 2023;58(4):393-400
Abstract
Allogeneic hematopoietic cell transplantation (allo-HCT) with reduced intensity conditioning (RIC) is an option for elderly patients with acute lymphoblastic leukemia (ALL). We retrospectively compared results of RIC-allo-HCT from either a matched sibling donor (MSD, n = 209) or matched unrelated donor (MUD, n = 209) with autologous (auto, n = 142) HCT for patients aged 55 years or more treated in first complete remission (CR1) between 2000 and 2018. The probabilities of leukemia-free survival (LFS) at 5 years were 34% for RIC-allo-HCT versus 39% for auto-HCT (p = 0.11) while overall survival (OS) rates were 42% versus 45% (p = 0.23), respectively. The incidence of relapse (RI) and non-relapse mortality (NRM) was 41% versus 51% (p = 0.22) and 25% versus 10% (p = 0.001), respectively. In a multivariate model, using auto-HCT as reference, the risk of NRM was increased for MSD-HCT (Hazard ratio [HR] = 2.1, p = 0.02) and MUD-HCT (HR = 3.08, p < 0.001), which for MUD-HCT translated into a decreased chance of LFS (HR = 1.55, p = 0.01) and OS (HR = 1.62, p = 0.008). No significant associations were found with respect to the risk of relapse. We conclude that for patients with ALL in CR1, aged above 55 years, auto-HCT may be considered a transplant option alternative to RIC-allo-HCT, although its value requires verification in prospective trials.
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Comorbidities in recipients of low transplant conditioning intensity regimens for acute myeloid leukemia: an ALWP EBMT study
Fein, J. A., Shouval, R., Galimard, J. E., Labopin, M., Socié, G., Finke, J., Cornelissen, J. J., Malladi, R., Itälä-Remes, M., Chevallier, P., et al
Blood advances. 2023
Abstract
Older age and high burden of comorbidities often drive selection of low-intensity conditioning regimens in allogeneic-hematopoietic stem cell transplantation (HSCT) recipients. However, the impact of comorbidities in the low-intensity conditioning setting is unclear. We sought to determine the contribution of individual comorbidities and their cumulative burden on the risk of non-relapse mortality (NRM) in patients receiving low-intensity regimens. In a retrospective analysis of adults (≥ 18 years) transplanted for acute myeloid leukemia (AML) in first complete remission (CR) between 2008-2018, we studied recipients of low-intensity regimens as defined by the Transplantation Conditioning Intensity (TCI) scale. Multivariable Cox models were constructed to study associations of comorbidities with NRM. Comorbidities identified as putative risk factors in the low-TCI setting were included in combined multivariable regression models assessed for overall survival, NRM, and relapse. A total of 1,663 patients with a median age of 61 years received low-TCI regimens. Cardiac comorbidity (including arrhythmia/valvular disease) and psychiatric disease were associated with increased NRM risk (hazard ratio [HR] 1.54 [95% CI 1.13, 2.09] and 1.69 [1.02, 2.82], respectively). Moderate pulmonary dysfunction, though prevalent, was not associated with increased NRM. In a combined model, cardiac, psychiatric, renal, and inflammatory bowel disease were independently associated with adverse transplantation outcomes. These findings may inform patient and regimen selection and reinforce the need for further investigation of cardioprotective transplantation approaches.
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5.
Myeloablative or reduced-intensity/non-myeloablative hematopoietic cell transplantation for Philadelphia-positive acute lymphoblastic leukemia in adults older than 40 years old - a secondary analysis of a CIBMTR database
de Oliveira Fernandes Junior, I., Arcuri, L. J.
Annals of hematology. 2023
Abstract
Few studies have addressed the role of reduced-intensity conditioning (RIC) and non-myeloablative (NMA) regimens in older adults with Philadelphia acute lymphoblastic leukemia (Ph + ALL). The objective of this current study was to compare the outcomes of RIC/NMA versus TBI-based myeloablative (MAC) regimens in Ph + ALL patients older than 40 years old who underwent hematopoietic cell transplantation (HCT) in CR1. We used a freely available database from the CIBMTR. Transplants were performed between 2013 and 2017. With a median follow-up of 37.6 months, we have included 629 patients. We used propensity score weighting. Three-year OSs were 64% in the TBI-MAC group and 66% in the RIC/NMA group. OS was not different (HR = 0.92; p = 0.69). Three-year relapse incidences were 21.6% and 27.6% in the TBI-MAC and RIC/NMA groups. RIC/NMA was not associated with an increase in relapse rate (HR 1.02; p = 0.91). Three-year NRMs were 24.3% in the TBI-MAC group and 20.3% in the RIC/NMA group. RIC/NMA was not associated with superior NRM (HR 0.88; p = 0.57). In summary, we have shown that RIC/NMA regimens achieve outcomes comparable to TBI-based MAC in Ph+ ALL older patients in CR1 who may tolerate a TBI-based MAC regimen.
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6.
Association between the choice of the conditioning regimen and outcomes of allogeneic hematopoietic cell transplantation for myelofibrosis
Murthy, G. S. G., Kim, S., Estrada-Merly, N., Abid, M. B., Aljurf, M., Assal, A., Badar, T., Badawy, S. M., Ballen, K., Beitinjaneh, A., et al
Haematologica. 2023
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Free full text
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Editor's Choice
Abstract
Allogeneic hematopoietic cell transplantation (allo-HCT) remains the only curative treatment for myelofibrosis. However, the optimal conditioning regimen either with reduced intensity conditioning (RIC) or myeloablative conditioning (MAC) is not well known. Using the Center for International Blood and Marrow Transplant Research database, we identified adults aged ≥18 years with myelofibrosis undergoing allo-HCT between 2008-2019 and analyzed the outcomes separately in the RIC and MAC cohorts based on the conditioning regimens used. Among 872 eligible patients, 493 underwent allo-HCT using RIC (Fludarabine/busulfan=166, Fludarabine/melphalan=327) and 379 using MAC (Fludarabine/busulfan=247, Busulfan/cyclophosphamide=132). In multivariable analysis with RIC, Fludarabine/melphalan was associated with inferior overall survival (HR 1.80, 95% CI 1.15-2.81, p=0.009), higher early non-relapse mortality (HR 1.81, 95% CI 1.12-2.91, p=0.01) and higher acute graft versus host disease (GVHD) (grade II-IV- HR 1.45, 95% CI 1.03-2.03, p=0.03; grade III-IV HR 2.21, 95%CI 1.28-3.83, p=0.004) compared to Fludarabine/busulfan. In the MAC setting, Busulfan/cyclophosphamide was associated with a higher acute GVHD (grade II-IV HR 2.33, 95% CI 1.67-3.25, p<0.001; grade III-IV HR 2.31, 95% CI 1.52-3.52, p<0.001) and inferior GVHD-free relapse-free survival (GRFS) (HR 1.94, 95% CI 1.49-2.53, p<0.001) as compared to Fludarabine/busulfan. Hence, our study suggests that Fludarabine/busulfan is associated with better outcomes in RIC (better overall survival, lower early non-relapse mortality, lower acute GVHD) and MAC (lower acute GVHD and better GRFS) in myelofibrosis.
PICO Summary
Population
Adults with myelofibrosis undergoing allogeneic HSCT between 2008-2019 and reported to the CIBMTR database (n=872)
Intervention
Reduced intensity conditioning (RIC) regimens (n=493): fludarabine/busulfan (n=166) or fludarabine/melphalan (n=327)
Comparison
Myeloablative conditioning (MAC) regimens (n=379): fludarabine/busulfan (n=247) or busulfan/cyclophosphamide (n=132).
Outcome
In multivariable analysis with RIC, fludarabine/melphalan was associated with inferior overall survival (HR 1.80, 95% CI 1.15-2.81), higher early non-relapse mortality (HR 1.81, 95% CI 1.12-2.91,) and higher acute graft versus host disease (GVHD) (grade II-IV- HR 1.45, 95% CI 1.03-2.03; grade III-IV HR 2.21, 95%CI 1.28-3.83) compared to fludarabine/busulfan. In the MAC setting, busulfan/cyclophosphamide was associated with a higher acute GVHD (grade II-IV HR 2.33, 95% CI 1.67-3.25; grade III-IV HR 2.31, 95% CI 1.52-3.52) and inferior GVHD-free relapse-free survival (GRFS) (HR 1.94, 95% CI 1.49-2.53) as compared to fludarabine/busulfan.
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7.
Novel risk assessment for the intensity of conditioning regimen in elderly patients
Akahoshi, Y., Tada, Y., Sakaida, E., Kusuda, M., Doki, N., Uchida, N., Fukuda, T., Tanaka, M., Sawa, M., Katayama, Y., et al
Blood advances. 2022
Abstract
Reduced-intensity conditioning (RIC) regimens have long-term outcomes that are generally comparable to those with myeloablative conditioning (MAC) due to a lower risk of NRM but a higher risk of relapse. However, it is unclear how we should select the conditioning intensity in individual cases. We propose the Risk assessment for the Intensity of Conditioning regimen in Elderly patients (RICE) score. We retrospectively analyzed 6147 recipients aged 50-69 years using a Japanese registry database. Based on the interaction analyses, advanced age (≥ 60 y), Hematopoietic Cell Transplantation-Specific Comorbidity Index (≥ 2), and umbilical cord blood were used to design a scoring system to predict the difference in an individual patient's risk of nonrelapse mortality (NRM) between MAC and RIC - the RICE score, which is the sum of these three factors: 0 or 1, low RICE score; or 2 or 3, high RICE score. In multivariate analyses, RIC was significantly associated with a decreased risk of NRM in patients with a high RICE score (training cohort: HR, 0.73, 95%CI, 0.60-0.90, P = 0.003; validation cohort: HR, 0.57, 95%CI, 0.43-0.77, P < 0.001). In contrast, we found no significant differences in NRM between MAC and RIC in patients with a low RICE score (training cohort: HR, 0.99, 95%CI, 0.85-1.15, P = 0.860; validation cohort: HR, 0.81, 95%CI, 0.66-1.01, P = 0.061). In summary, a new and simple scoring system, the RICE score, appears to be useful for personalizing the conditioning intensity and might improve transplant outcomes in elderly patients.
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8.
Myeloablative Versus Reduced-Intensity Conditioning With Fludarabine/Busulfan for Myelodysplastic Syndrome: A Propensity Score-Matched Analysis
Kurosawa, S., Shimomura, Y., Itonaga, H., Najima, Y., Kobayashi, T., Ozawa, Y., Kanda, Y., Kako, S., Kawakita, T., Matsuoka, K. I., et al
Transplantation and Cellular Therapy. 2022;28(6):323.e1-323.e9
Abstract
There are limited data comparing myeloablative conditioning with fludarabine/busulfan (Flu/Bu4) and reduced-intensity conditioning with fludarabine/busulfan (Flu/Bu2) in patients with myelodysplastic syndrome (MDS) undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). We retrospectively analyzed nationwide registry data and compared the outcomes of adult patients with MDS receiving Flu/Bu4 and Flu/Bu2 by propensity score (PS) matching. Patients who met the following criteria were eligible for enrollment: (1) age ≥16 years; (2) diagnosis of de novo MDS; (3) first allo-HSCT between 2006 and 2018; (4) related bone marrow transplantation (BMT) or peripheral blood stem cell transplantation from an HLA-matched donor, unrelated BMT from an HLA-matched or HLA-1 allele-mismatched donor, or unrelated cord blood transplantation; and (5) receiving Flu/Bu4 or Flu/Bu2 as a conditioning regimen. Flu/Bu4 comprised intravenous busulfan (total dose, 12.8 mg/kg) combined with fludarabine (total dose, 125-180 mg/m(2)). Flu/Bu2 comprised intravenous busulfan (total dose, 6.4 mg/kg) combined with the same dose of fludarabine. To minimize selection bias and confounding factors, we performed a propensity score (PS)-matched analysis. The primary endpoint was overall survival (OS) after allo-HSCT. A total of 3386 patients with de novo MDS underwent their first allo-HSCT between 2006 and 2018. Among them, 202 patients were assigned each to the Flu/Bu4 and Flu/Bu2 groups after PS-matched analysis. The median age was 61 (interquartile, 57-65) years. The 3-year OS rates were 44.8% (95% confidence interval [CI], 37.1-52.1%) and 46.9% (95% CI, 39.2-54.2%) in the Flu/Bu4 and Flu/Bu2 groups, respectively (P = .67). The 3-year rates of graft-versus-host disease (GVHD)-free survival, relapse-free survival (GRFS) were 28.8% (95% CI, 22.2-35.7%) and 33.0% (95% CI, 26.2-40.0%), respectively (P = .36). The 3-year cumulative incidence rates of relapse were 28.9% (95% CI, 22.6-35.6%) and 30.0% (95% CI, 23.6-36.6%), respectively (P = .47). The 3-year cumulative incidence rates of non-relapse mortality (NRM) were 28.2% (95% CI, 21.7-35.0%) and 27.1% (95% CI, 20.6-33.9%), respectively (P = .60). The 100-day cumulative incidence rate of grade II-IV acute GVHD was significantly higher in the Flu/Bu4 group than in the Flu/Bu2 group (41.7% [95% CI, 34.8%-48.4%] versus 29.3% [95% CI, 23.2%-35.7%], P = 0.012). To identify patients who had more favorable outcomes with 1 of the 2 regimens, we compared the outcomes between the 2 groups after stratifying by age, hematopoietic cell transplantation-comorbidity index, cytogenetic risk, disease status at allo-HSCT, stem cell source, and donor type. OS, GRFS, relapse, and NRM did not differ between the 2 groups in any subgroup analyses. There were no significant interactions between the choice of conditioning regimens and any other factors. There are no differences in survival between Flu/Bu4 and Flu/Bu2, although our study population was highly selected by PS matching. Data from more patients and prospective studies are needed to determine the optimal intensity of conditioning regimens in patients with MDS.
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9.
Augmented FLAMSA-Bu versus FluBu2 reduced-intensity conditioning in patients with active relapsed/refractory acute myeloid leukemia: an EBMT analysis
Rodríguez-Arbolí, E., Labopin, M., Eder, M., Brecht, A., Blau, I. W., Huynh, A., Forcade, E., Tischer, J., Bethge, W., Bondarenko, S., et al
Bone marrow transplantation. 2022
Abstract
Comparative data of fludarabine, cytarabine and amsacrine (FLAMSA) chemotherapy followed by busulfan (Bu)-based reduced-intensity conditioning (RIC) (FLAMSA-Bu) versus RIC regimens are lacking in patients with active relapsed/refractory (R/R) acute myeloid leukemia (AML) at the time of allogeneic hematopoietic stem cell transplantation (alloSCT). Here, we retrospectively analyzed outcomes after FLAMSA-Bu versus fludarabine/busulfan (FluBu2) conditioning in this patient population. A total of 476 patients fulfilled the inclusion criteria, of whom 257 received FluBu2 and 219 FLAMSA-Bu. Median follow-up was 41 months. Two-year non-relapse mortality (21%), graft-versus-host disease-free, relapse-free survival (24%) and chronic graft-versus-host disease (GVHD) (29%) were not statistically different between cohorts. FLAMSA-Bu was associated with lower 2-year relapse incidence (RI) (38 vs 49% after FluBu2, p = 0.004), and increased leukemia-free survival (LFS) (42 vs 29%, p = 0.001), overall survival (47 vs 39%, p = 0.008) and grades II-IV acute GVHD (36 vs 20%, p = 0.001). In the multivariate analysis, FLAMSA-Bu remained associated with lower RI (HR 0.69, p = 0.042), increased LFS (HR 0.74, p = 0.048) and a higher risk of acute GVHD (HR 2.06, p = 0.005). Notwithstanding the limitations inherent in this analysis, our data indicate that FLAMSA-Bu constitutes a tolerable conditioning strategy, resulting in a long-term benefit in a subset of patients reaching alloSCT with active disease.
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10.
Fludarabine and Melphalan Compared with Reduced Doses of Busulfan and Fludarabine Improves Transplant Outcomes in Older MDS Patients
Oran, B., Ahn, K. W., Fretham, C., Beitinjaneh, A., Bashey, A., Pawarode, A., Wirk, B., Scott, B. L., Savani, B. N., Bredeson, C., et al
Transplantation and cellular therapy. 2021
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Free full text
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Editor's Choice
Abstract
Reduced-intensity conditioning (RIC) regimens developed to extend allogeneic stem cell transplantation (HSCT) to older patients have resulted in encouraging outcomes. We aimed to compare the two most commonly used RIC regimens, intravenous use of fludarabine with busulfan (FluBu) and fludarabine with melphalan (FluMel), in myelodysplastic syndrome (MDS). Through CIBMTR, we identified 1045 MDS patients aged = 60 years who underwent first HSCT with a matched related or matched (8/8) unrelated donor using RIC. CIBMTR's definition of RIC was used: a regimen that incorporated an intravenous busulfan total dose = 7.2 mg/kg, or a low-dose melphalan total dose of = 150 mg/m(2). The two groups, FluBu (n=697) and FluMel (n=448), were comparable for disease and transplant-related characteristics except for the more frequent use of anti-thymocyte globulin or alemtuzumab in the FluBu group (39% vs. 31%). The median age was 67 in both groups. FluMel was associated with a reduced relapse incidence (RI) compared with FluBu, with a 1-year adjusted incidence of 26% vs. 44% (p=0.0001). Transplant-related mortality (TRM) was higher with FluMel compared with FluBu (26% vs. 16%, p=0.0001). Since the magnitude of improvement with FluMel in RI was greater than the improvement in TRM with FluBu, disease-free survival (DFS) was improved at 1-year and beyond with FluMel compared with FluBu (48% vs. 40% at 1 year, p=0.02, and 35% vs. 27% at 3 years, p=0.01). Overall survival (OS) was comparable at 1 year (63% vs. 61%, p=0.4) but significantly improved with FluMel compared with FluBu at 3 years (46% vs. 39%, p=0.03). Our results suggest that FluMel is associated with superior DFS compared with FluBu due to reduced RI in older MDS patients.
PICO Summary
Population
Patients with myelodysplastic syndrome aged >/=60 years who underwent first HSCT with a matched related or matched (8/8) unrelated donor, and were reported to the CIBMTR registry (n=1045)
Intervention
Reduced intensity regimen incorporating an intravenous busulfan total dose = 7.2 mg/kg (FluBu, n=697)
Comparison
Reduced intensity regimen incorporating a low-dose melphalan total dose of = 150 mg/m(2) (FluMel, n=448)
Outcome
The two groups were comparable for disease and transplant-related characteristics except for the more frequent use of anti-thymocyte globulin or alemtuzumab in the FluBu group (39% vs. 31%). The median age was 67 in both groups. FluMel was associated with a reduced relapse incidence (RI) compared with FluBu, with a 1-year adjusted incidence of 26% vs. 44%. Transplant-related mortality (TRM) was higher with FluMel compared with FluBu (26% vs. 16%). Since the magnitude of improvement with FluMel in RI was greater than the improvement in TRM with FluBu, disease-free survival (DFS) was improved at 1-year and beyond with FluMel compared with FluBu (48% vs. 40% at 1 year, and 35% vs. 27% at 3 years). Overall survival (OS) was comparable at 1 year (63% vs. 61%) but significantly improved with FluMel compared with FluBu at 3 years (46% vs. 39%). Our results suggest that FluMel is associated with superior DFS compared with FluBu due to reduced RI in older MDS patients.