Fludarabine-Busulfan Reduced-Intensity Conditioning in Comparison with Fludarabine-Melphalan Is Associated with Increased Relapse Risk In Spite of Pharmacokinetic Dosing

Melphalan Dose in Combination with Fludarabine Affects GI Toxicity and GVHD after Allogeneic Transplantation in Acute Myeloid Leukemia and Myelodysplastic Syndromes

Fludarabine (Flu) and melphalan (Mel) reduced-intensity conditioning is frequently used for allogenic hematopoietic cell transplant (allo-HCT) in patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). However, there is limited evidence on the impact of Mel dosing on toxicities and clinical outcomes of allo-HCT. We retrospectively compared 8/8 HLA matched donor allo-HCT outcomes of 345 patients with AML or MDS receiving total Mel dose of 100 mg/m2 (Mel-100, n=62) versus 140 mg/m2 (Mel-140, n=283) in combination with Flu. Median age at allo-HCT was 66 years and median follow-up was 36.5 months. For Mel-100 versus Mel-140 groups, any grade gastrointestinal toxicity rates were 40.3% vs. 67.8% (p<0.001), day 100 grade II-IV acute graft-versus-host disease (GVHD) rates were 21.0% vs. 43.1% (p=0.001) and 2-year chronic GVHD rates were 17.4% vs. 27.1% (p=0.033). In multivariable analysis, Mel-140 resulted in higher risks of gastrointestinal toxicity (HR=1.83, p=0.013), grade II-IV acute GVHD (HR=2.35, p=0.003), and moderate/severe chronic GVHD (HR=3.13, p=0.007). Total Mel dose had no independent impact on oral mucositis, non-relapse mortality, relapse, relapse-free survival, and overall survival. While independent validation of our observation is warranted, our findings support using Mel-100 in combination with Flu to minimize allo-HCT toxicities and morbidities related to GVHD.

Intensive Reinduction Chemotherapy Followed by Early Allogeneic Hematopoietic Cell Transplantation for Relapsed/Refractory High-Grade Myeloid Neoplasms

Outcomes for adults with relapsed/refractory (R/R) high-grade myeloid neoplasms remain poor, with allogeneic hematopoietic cell transplantation (HCT) the sole therapy likely to result in cure. We conducted the present study to determine the feasibility of early HCT-within 60 days of beginning reinduction chemotherapy-to see whether getting patients to HCT in an expeditious manner would expand the number of patients being offered this curative option. In this proof-of-principle feasibility study, we included adults age 18 to 75 years with R/R myeloid malignancies with ≥10% blood/marrow blasts at diagnosis who were eligible for a reduced-intensity HCT. Subjects received reinduction chemotherapy with cladribine, cytarabine, mitoxantrone, and filgrastim (CLAG-M) and proceeded to HCT with reduced-intensity conditioning (fludarabine/ melphalan). We enrolled 30 subjects, all of whom received CLAG-M reinduction, although only 9 underwent HCT within 60 days (<15, the predetermined threshold for feasibility "success"), with a median time to HCT of 48 days (range, 42 to 60 days). Eleven additional subjects received HCT beyond the target 60 days (off-study), with a median time to transplantation of 83 days (range, 53 to 367 days). Barriers to early HCT included infection, physician preference, lack of an HLA-matched donor, logistical delays, and disease progression, all of which may limit the real-world uptake of such early-to-transplantation protocols.

Impact of Different Fludarabine Doses in the Fludarabine-Based Conditioning Regimen for Unrelated Bone Marrow Transplantation

The purine analog fludarabine (Flu) plays a central role in reduced-intensity conditioning and myeloablative reduced-toxicity conditioning regimens because of limited nonhematologic toxicities. Few reports assess the impact of different dose of Flu on the clinical outcomes and the Flu doses vary across reports. To compare the effect of Flu dose, the clinical outcomes of patients who received Flu and busulfan (FB; n = 1647) or melphalan (Flu with melphalan (FM); n = 1162) conditioning for unrelated bone marrow transplantation were retrospectively analyzed using Japanese nationwide registry data. In the FB group, high-dose Flu (180 mg/m2; HFB) and low-dose Flu (150/125 mg/m2; LFB) were given to 1334 and 313 patients, respectively. The 3-year overall survival (OS) rates were significantly higher in the HFB group than in the LFB group (49.5% versus 39.2%, P < .001). In the HFB and LFB groups, the cumulative incidences were 30.4% and 36.6% (P = .058) for 3-year relapse and 25.1% and 28.1% (P = .24) for 3-year nonrelapse mortality (NRM), respectively. In the multivariate analysis for OS and relapse, Flu dose was identified as an independent prognostic factor (hazard ratio: 0.83, P = .03; hazard ratio: 0.80, P = .043). In the FM group, high-dose Flu (180 mg/m2; HFM) and low-dose Flu (150/125 mg/m2; LFM) were given to 118 and 1044 patients, respectively. The OS, relapse, and NRM after 3 years did not differ significantly between the HFM and LFM groups (48.3% versus 48.8%, P = .92; 23.7% versus 27.2%, P = .55; 31.9% versus 30.8%, P = .67). These findings suggest that high-dose Flu was associated with favorable outcomes in the FB group but not in the FM group.

Busulfan and subsequent malignancy: An evidence-based risk assessment

BACKGROUND

The incidence of secondary malignancies associated with busulfan exposure is considered low, but has been poorly characterized. Because this alkylating agent is increasingly utilized as conditioning prior to gene therapy in nonmalignant hematologic and related disorders, more precise characterization of busulfan's potential contribution to subsequent malignant risk is warranted.

PROCEDURE

We conducted a literature-based assessment of busulfan and subsequent late effects, with emphasis on secondary malignancies, identifying publications via PubMed searches, and selecting those reporting at least 3 years of follow-up.

RESULTS

We identified eight pediatric and 13 adult publications describing long-term follow-up in 570 pediatric and 2076 adult hematopoietic cell transplant (HCT) recipients. Secondary malignancies were reported in 0.5% of pediatric HCT recipients, with no cases of myelodysplastic syndrome (MDS) or acute myelocytic leukemia (AML). Fatal secondary malignancies were reported in 0.8% of 1887 evaluable adult HCT recipients, and an overall incidence of secondary malignancies of 4.8% was reported in a subset of 389 evaluable adult patients. We also reviewed long-term results from eight publications evaluating lentiviral- and human promotor-based HSC-targeted gene therapy in 215 patients with nonmalignant conditions, in which busulfan/treosulfan monotherapy or busulfan/fludarabine was the only conditioning. Two malignancies were reported in patients with sickle cell disease (SCD), one of which was potentially busulfan-related. No additional malignancies were reported in 173 patients with follow-up of 5-12 years.

CONCLUSION

The incidence of busulfan-related secondary malignancies is low, and likely to be substantially less than 1% in pediatric transplant recipients, especially those receiving busulfan monotherapy for nonmalignant conditions other than SCD.

Fludarabine melphalan versus fludarabine treosulfan for reduced intensity conditioning regimen in allogeneic hematopoietic stem cell transplantation: a retrospective analysis

Various reduced-intensity conditioning (RIC) regimens are used to decrease toxicity while providing comparable outcomes to myeloablative regimens. We compared toxicity and outcomes between two RIC regimens, fludarabine with melphalan (Flu-Mel) and fludarabine with treosulfan (Flu-Treo), retrospectively over a 10-year period in two donor groups, matched related donor (MRD)/matched unrelated donor (MUD) and haploidentical (Haplo) transplants. The study included 138 patients, of which 105 received MRD/MUD (Flu-Mel: 94, Flu-Treo: 11) and 33 Haplo (Flu-Mel: 17, Flu-Treo: 16) transplants. In the MRD/MUD group, 44 (47%) of patients who received Flu-Mel had grade 3/4 oral mucositis compared to 1 (9%) who received Flu-Treo (P = 0.02). Corresponding numbers in the Haplo group were 7 (41%) and 1 (6%). Grade 3/4 diarrhoea was more frequent with Flu-Mel than Flu-Treo in the Haplo group (41% vs 6%; P = 0.039), but not the MRD/MUD group. Median follow-up time for all patients was 4.8 years. Five-year OS in the MRD/MUD group was 62% with Flu-Mel versus 53% with Flu-Treo (P = 0.0694). Similarly, 5-year OS was 41% with Flu-Mel and 28% with Flu-Treo (P = 0.770) in the Haplo group. Severe mucositis and diarrhoea were significantly less frequent with Flu-Treo than Flu-Mel. Flu-Treo provided comparable outcomes to Flu-Mel in all donor transplants.

Outcome improvement over time in reduced intensity conditioning hematopoietic transplantation: a 20-year experience

The current study includes all consecutive patients (N = 484) who received a reduced-intensity conditioning regimen (RIC) allogeneic hematopoietic stem cell transplantation in our center from 1999 to 2020. Conditioning regimens were based on fludarabine with melphalan or busulfan, with low-dose thiotepa and pharmacological GVHD prophylaxis consisted of cyclosporine A (CsA)-methotrexate (MTX)/mofetil (MMF) (n = 271), tacrolimus-sirolimus (n = 145), and post-transplantation cyclophosphamide (PTCy)-tacrolimus (n = 68). The median time of overall follow-up in survivors was 8 years (1-22 years) and was at least 3 years in all three GVHD prophylaxis groups. Thirty-three percent had a high or very high disease risk index, 56% ≥ 4 European bone marrow transplantation risk, and 65% ≥ 3 hematopoietic stem cell transplantation comorbidity index score-age score. Neutrophil and platelet engraftment was longer for PTCy-tacro (p 0.0001). Cumulative incidence of grade III-IV aGVHD was 17% at 200 days, and that of moderate-severe cGvHD was 36% at 8 years. GVHD prophylaxis was the only prognostic factor in the multivariable analyses for the development of aGVHD and moderate-severe cGVHD (p 0.0001). NRM and relapse incidences were 29% and 30% at 8 years, while OS and PFS rates were 43% and 39% at 8 years. At 3 years, OS was highest in the PTCy-tacro group (68%) than in the tacro-siro (61%) and CsA-MTX/MMF (49%) cohorts (p < 0.01). In the three groups, respectively, the 200-day incidence of grade III-IV aGvHD (6% vs. 12% vs. 23%) and 3-year moderate-severe cGVHD (8% vs. 40% vs. 38%) were lower in the PTCy cohort. These better outcomes were confirmed in multivariable analyses. Based on our recent results, the PTCy could be considered as a real GvHD prophylaxis in the RIC setting due to improve best 3-year GvHD and survival outcomes.

Cardiovascular events among recipients of hematopoietic stem cell transplantation-A systematic review and meta-analysis

Cardiovascular diseases are an emerging cause of mortality and morbidity in survivors of hematopoietic stem cell transplantation (HSCT); however, the incidence of cardiovascular events (CVEs) in this population is not well described. This systematic review summarizes the evidence on the incidence of CVEs in HSCT recipients. Medline and Embase were searched from inception to December 2020. Inclusion criteria were cohort studies and phase 3 randomized controlled trials that reported CVEs among adults who underwent HSCT for hematological malignancies. After reviewing 8386 citations, 57 studies were included. The incidence of CVEs at 100 days was 0.19 (95% CI: 0.17-0.21) per 100 person-days after autologous HSCT and 0.06 (95% CI: 0.05-0.07) per 100 person-days after allogeneic HSCT. This higher incidence after autologous HSCT was driven by reports of arrhythmia from one population-based study in patients with multiple myeloma. The incidence of long-term CVEs was 3.98 (95% CI; 3.44-4.63) per 1000 person-years in survivors of autologous HSCT and 3.06 (95% CI; 2.69-3.48) per 1000 person-years in survivors of allogeneic HSCT. CVEs remain an important but under-reported cause of morbidity and mortality in recipients of HSCT. Future studies are required to better understand the incidence and risk factors for CVEs in HSCT recipients.

Day 4 vs. day 12 G-CSF administration following reduced intensity peripheral blood allogeneic stem cell transplant

INTRODUCTION

Granulocyte colony-stimulating factor (G-CSF) hastens neutrophil engraftment and reduces infections after allogeneic hematopoietic cell transplant (alloHCT), yet the optimal start date is unknown. Additionally, concurrent G-CSF and methotrexate for graft-vs-host disease (GVHD) prophylaxis may potentiate myelosuppression, and prolonged G-CSF is costly. Our institution changed from day + 4 to day + 12 G-CSF initiation following reduced intensity (RIC) alloHCT with methotrexate GVHD prophylaxis.

METHODS

We retrospectively compared day + 4 and day + 12 G-CSF initiation after RIC alloHCT from 2017-2021. The primary endpoint was the time to neutrophil engraftment. Secondary endpoints included length of stay (LOS) and the time to platelet engraftment as well as the incidence of infectious events, acute GVHD (aGVHD), and mucositis.

RESULTS

Thirty-two patients were included in each group with similar baseline characteristics. We observed faster neutrophil engraftment (median 12 vs. 15 days, p = 0.01) and platelet engraftment (median 13 vs. 15 days, p = 0.026) with day + 4 vs. day + 12 G-CSF initiation. Median LOS was 23 days (range, 19-32) with day + 4 initiation vs. 24 days (21-30) with day + 12 (p = 0.046). The incidence of culture-negative febrile neutropenia (p = 0.12), any grade aGVHD (p = 0.58), and grade 2-4 mucositis (p = 0.8) were similar between groups.

CONCLUSION

Compared to day + 4, day + 12 G-CSF initiation following RIC alloHCT had a longer time to neutrophil and platelet engraftment. Day + 12 initiation also resulted in longer LOS, which while statistically significant, was potentially of limited clinical significance. These findings are hypothesis generating.

OUP accepted manuscript

As in younger patients, allogeneic stem cell transplantation (alloHSCT) offers the best chance for durable remission in older patients (≥60 years) with acute myeloid leukemia (AML). However, defining the best treatment strategy (and in particular, whether or not to proceed to alloHSCT) for elderly patients with AML remains a difficult decision for the hematologist, since potential toxicity of conditioning regimens, risks of graft-versus-host disease, impaired immune reconstitution and the need for prolonged immunosuppression may be of major concern in these vulnerable patients with complex needs. Hopefully, significant progress has been made over the past decade in alloHSCT for elderly patients and current evidence suggests that chronological age per se (between 60 and 75) is not a reliable predictor of outcome after alloHSCT. Here, we review the current state of alloHSCT in elderly patients with AML and also discuss the different approaches currently being investigated to improve both accessibility to as well as success of alloHSCT in these patients.

Impact of conditioning intensity and regimen on transplant outcomes in patients with adult T-cell leukemia-lymphoma

In allogeneic hematopoietic cell transplantation (allo-HCT) for adult T-cell leukemia-lymphoma (ATL), the optimal conditioning regimens have not yet been determined. We conducted a Japanese nationwide, retrospective study to investigate this issue. This study included 914 ATL patients who underwent allo-HCT between 1995 and 2015. In patients aged 55 years or younger, there was no statistically significant difference between reduced-intensity conditioning (RIC) regimens and myeloablative conditioning (MAC) regimens regarding risk of relapse (vs. RIC group: MAC group, hazard ratio (HR) 0.76, P = 0.071), non-relapse mortality (vs. RIC group: MAC group, HR 1.38, P = 0.115), or overall mortality (vs. RIC group: MAC group, HR 1.17, P = 0.255). Among RIC regimens, fludarabine plus melphalan-based (Flu/Mel) regimens were associated with a lower risk of relapse (Flu/Mel140 group, HR 0.59, P < 0.001; Flu/Mel80 group, HR 0.79, P = 0.021) than the Flu plus busulfan-based regimen (Flu/Bu2 group). Meanwhile, Flu/Mel140 group had a significantly higher risk of non-relapse mortality (vs. Flu/Bu2 group: HR 1.53, P = 0.025). In conclusion, it is acceptable to select a RIC regimen for younger patients. Moreover, it might be beneficial to select a Flu/Mel-based regimen for patients at high risk of relapse.

Fludarabine and Melphalan Compared with Reduced Doses of Busulfan and Fludarabine Improve Transplantation Outcomes in Older Patients with Myelodysplastic Syndromes

Reduced-intensity conditioning (RIC) regimens developed to extend the use of allogeneic hematopoietic stem cell transplantation (HSCT) to older patients have resulted in encouraging outcomes. We aimed to compare the 2 most commonly used RIC regimens, i.v. fludarabine with busulfan (FluBu) and fludarabine with melphalan (FluMel), in patients with myelodysplastic syndrome (MDS). Through the Center for International Blood and Marrow Transplant Research (CIBMTR), we identified 1045 MDS patients age ≥60 years who underwent first HSCT with a matched related or matched (8/8) unrelated donor using an RIC regimen. The CIBMTR's definition of RIC was used: a regimen that incorporated an i.v. busulfan total dose ≤7.2 mg/kg or a low-dose melphalan total dose ≤150 mg/m². The 2 groups, recipients of FluBu (n = 697) and recipients of FluMel (n = 448), were comparable in terms of disease- and transplantation-related characteristics except for the more frequent use of antithymocyte globulin or alemtuzumab in the FluBu group (39% versus 31%). The median age was 67 years in both groups. FluMel was associated with a reduced relapse incidence (RI) compared with FluBu, with a 1-year adjusted incidence of 26% versus 44% (P ≤ .0001). Transplantation-related mortality (TRM) was higher in the FluMel group (26% versus 16%; P ≤ .0001). Because the magnitude of improvement with FluMel in RI was greater than the improvement in TRM with FluBu, disease-free survival (DFS) was better at 1 year and beyond with FluMel compared with FluBu (48% versus 40% at 1 year [P = .02] and 35% versus 27% at 3 years [P = .01]). Overall survival (OS) was comparable in the 2 groups at 1 year (63% versus 61%; P = .4) but was significantly improved with FluMel compared with FluBu at 3 years (46% versus 39%; P = .03). Our results suggest that FluMel is associated with superior DFS compared with FluBu owing to reduced RI in older patients with MDS patients. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Allogeneic hematopoietic cell transplantation using fludarabine plus myeloablative busulfan and melphalan confers promising survival in high-risk hematopoietic neoplasms: a single-center retrospective analysis

OBJECTIVES

Optimal selection of pretransplant conditioning is crucially vital for improving survival and quality-of-life of patients who receive allogeneic hematopoietic cell transplantation (allo-HCT), particularly in those with high-risk diseases. In this study, we evaluated the efficacy and safety of recently-developed reduced-toxicity myeloablative regimen that combines fludarabine, intravenous busulfan, and melphalan (FBM).

METHODS

We conducted a single-center retrospective analysis of 39 patients (23 with myeloid neoplasms and 16 with lymphoid neoplasms), with a median age of 50 (range, 17-68) years, who underwent their first allo-HCT using the FBM regimen. Graft types were bone marrow in 11, peripheral blood in 11, and cord blood in 17 patients. Cyclosporine- or tacrolimus-based graft-versus-host disease (GVHD) prophylaxis was administered. The primary end point of the study was the overall survival rate at 2-year after transplantation.

RESULTS

After a median follow-up of 910 days for the surviving patients, 2-year overall survival was 62% for the entire cohort; 73% in the low-to-intermediate-risk group and 44% in the high-to-very high-risk group classified by the refined CIBMTR Disease Risk Index. Cumulative incidences of engraftment, grade II-IV acute GVHD, chronic GVHD, relapse, and non-relapse mortality were 95%, 56%, 56%, 31%, and 17%, respectively.

CONCLUSION

These results suggest that our FBM regimen can be applied to allo-HCT using various graft types and yields acceptable outcomes with relatively low non-relapse mortality in both myeloid and lymphoid neoplasms. Also, we observed a promising survival in the group of patients with high-risk diseases, warranting more accumulation of patients and longer follow-up.

Reduced intensity conditioning for acute myeloid leukemia using melphalan- vs busulfan-based regimens: a CIBMTR report

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.

Cord blood transplantation with a reduced-intensity conditioning regimen using fludarabine and melphalan for adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is a peripheral T-cell lymphoma with a poor prognosis when treated with chemotherapy alone; therefore, allogeneic stem cell transplantation is a consideration. We attempted cord blood transplantation (CBT) using a reduced-intensity conditioning regimen without total body irradiation (non-TBI-RIC) to allow for the best possible timing of transplantation and improve survival outcomes, particularly in older patients. Forty-eight patients (27 male, 21 female) underwent CBT using fludarabine (Flu) 125 mg/m² and melphalan (Mel) 140 mg/m² as pre-transplant conditioning. The median age was 32 years (range 44-72), and 21 patients were in complete remission (CR) at the time of CBT. The median duration to neutrophil engraftment (NE) was 19.5 days (range 15-50), with a cumulative incidence of NE of 86.7% at day 50 after CBT. The 1- and 3-year overall survival (OS) rates were 40.4% and 37.7%, respectively. The 3-year OS rate in CR patients was 60.8%, compared with 18.8% in non-CR patients. In ATLL patients, CBT with non-TBI-RIC using Flu/Mel is a promising treatment strategy.

Comparison of melphalan- And busulfan-based myeloablative conditioning in children undergoing allogeneic transplantation for acute myeloid leukemia or myelodysplasia

BACKGROUND

The optimal conditioning regimen for alloHCT in children with myeloid malignancies remains undefined.

PROCEDURE

We performed a retrospective review of children undergoing alloHCT for AML and MDS over a 10-year period (2008-2018) at our institution, comparing the outcomes of recipients of either a myeloablative busulfan- or reduced toxicity mel/thio-based conditioning regimen.

RESULTS

A total of 49 patients underwent alloHCT for AML/MDS (mel/thio, N = 21; busulfan, N = 28). Mel/thio recipients were selected due to pretransplant comorbidities. Recipients of mel/thio were more likely to have t-AML, and less likely to have MRD <0.1% at the time of alloHCT (57.1% vs 82.1%). Graft failure was more common in busulfan recipients; engraftment kinetics were similar between groups. Sinusoidal obstructive syndrome was diagnosed in 21% of busulfan and no mel/thio recipients (P = .03). One patient in each group died from TRM. Relapse incidence was comparable (mel/thio-29% vs busulfan-32%); however, relapse occurred significantly later in recipients of mel/thio conditioning (median d + 396 vs d + 137; P = .01). As a result, there was a trend toward improved OS at 1 and 3 years in mel/thio recipients (95% vs 74%, P = .06; and 75% vs 50%, P = .11; respectively).

CONCLUSION

In our single institution, when compared to myeloablative busulfan-based conditioning, use of a mel/thio-based reduced toxicity regimen resulted in comparable outcomes, despite higher risk patient and disease characteristics. Mel/thio recipients had both more comorbidities and higher risk disease profile, which did not translate into higher rates of either TRM or relapse.

Reduced-intensity fludarabine/melphalan confers similar survival to busulfan/fludarabine myeloablative regimens for patients with acute myeloid leukemia and myelodysplasia

Optimal conditioning chemotherapy for patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) remains uncertain. Myeloablative regimens such as fludarabine/busulfan are favored over reduced-intensity fludarabine/melphalan (Flu/Mel); however, it is not known if Flu/Mel is inferior. We analyzed hematopoietic cell transplantation recipients with AML and MDS who received fludarabine with once-daily intravenous busulfan targeted to either area under the curve (AUC) 5300 µM*L/min (Flu/Bu 5300) (n = 246) or AUC 3500 µM*L/min (Flu/Bu 3500) (n = 81), or Flu/Mel (n = 69). Flu/Bu regimens were compared separately to Flu/Mel. After 2-year follow-up, no differences in overall or relapse-free survival were found between Flu/Bu 5300 or 3500 versus Flu/Mel though relapse rates were significantly higher; 33.1% (p = 0.024), 44.6% (p = 0.002), versus 19.4%, respectively. Flu/Bu 5300 (p = 0.008) and Flu/Bu 3500 (p < 0.001) groups were prognostic for relapse compared to Flu/Mel. Flu/Mel yields lower relapse rates and similar survival benefit when compared to Flu/Bu 3500 or 5300 µM*L/min.

Is there an optimal conditioning for older patients with AML receiving allogeneic hematopoietic cell transplantation?

The optimal conditioning regimen for older patients with acute myeloid leukemia (AML) remains unclear. In this study, we compared outcomes of AML patients >60 years of age undergoing allogenic hematopoietic stem cell transplantation at our institution. All 404 consecutively treated patients received 1 of the following conditioning regimens: (1) fludarabine+melphalan 100 mg/m2 (FM100), (2) fludarabine+melphalan 140 mg/m2 (FM140), (3) fludarabine+IV busulfan AUC ≥ 5000/d × 4 d (Bu≥20000), and (4) fludarabine+IV busulfan AUC 4000/d × 4 d (Bu16000). A propensity score analysis (PSA) was used to compare outcomes between these 4 groups. Among the 4 conditioning regimens, the FM100 group had a significantly better long-term survival with 5-year progression-free survival of 49% vs 30%, 34%, and 23%, respectively. The benefit of the FM100 regimen resulted primarily from the lower nonrelapse mortality associated with this regimen, an effect more pronounced in patients with lower performance status. The PSA confirmed that FM100 was associated with better posttransplantation survival, whereas no significant differences were seen between the other regimen groups. In summary, older patients with AML benefited from a reduced-intensity conditioning regimen with lower melphalan doses (FM100), which was associated with better survival, even though it was primarily used in patients who could not receive a more intense conditioning regimen.

Comparison of reduced intensity conditioning regimens used in patients undergoing hematopoietic stem cell transplantation for myelofibrosis

The aim of this study is to compare clinical outcomes of patients who underwent allogeneic stem cell transplantation (HCT) for myelofibrosis with reduced intensity conditioning (RIC) using either Busulfan Fludarabine (BuFlu), Fludarabine Bis-chlorethyl-nitroso-urea/ carmustine Melphalan (FBM) or Fludarabine Melphalan (FluMel) regimens. Sixty-one patients were identified who underwent HCT with one of these RIC regimens. Overall survival (OS) was not different in the 3 groups. However, 100% donor chimerism was seen in more frequently at day +30 and day +100 in patients who received FBM or FluMel than BuFlu, in both CD3 and CD33 fractions. For instance, 100% donor chimerism in CD33 fraction was present in 100% patients in FBM cohort, 90% in FluMel cohort while 44% in BuFlu cohort at day +100. Acute graft-versus host disease, grade 2-4 and grade 3-4, was not statistically different in the 3 groups (BuFlu 47 and 35%, FBM 68 and 27%, FluMel 68 and 46%; p = 0.31 and 0.45). Relapses and non-relapse mortality was also not statistically significantly different. Our study shows similar OS with these 3 RIC regimens in myelofibrosis; although donor chimerism at day +30 and day +100 was better in patients who received FBM and FluMel.

Favorable impact of allogeneic stem cell transplantation in patients with therapy-related myelodysplasia regardless of TP53 mutational status

Therapy-related myelodysplastic syndrome is a long-term complication of cancer treatment in patients receiving cytotoxic therapy, characterized by high-risk genetics and poor outcomes. Allogeneic hematopoietic cell transplantation is the only potential cure for this disease, but the prognostic impact of pre-transplant genetics and clinical features has not yet been fully characterized. We report here the genetic and clinical characteristics and outcomes of a relatively large cohort of patients with therapy-related myelodysplastic syndrome (n=67) who underwent allogeneic transplantation, comparing these patients to similarly treated patients with de novo disease (n=199). The 5-year overall survival was not different between patients with therapy-related and de novo disease (49.9% versus 53.9%; P=0.61) despite a higher proportion of individuals with an Intermediate-2/High International Prognostic Scoring System classification (59.7% versus 43.7%; P=0.003) and high-risk karyotypes (61.2% versus 30.7%; P<0.01) among the patients with therapy-related disease. In mutational analysis, TP53 alteration was the most common abnormality in patients with therapy-related disease (n=18: 30%). Interestingly, the presence of mutations in TP53 or in any other of the high-risk genes (EZH2, ETV6, RUNX1, ASXL1: n=29: 48%) did not significantly affect either overall survival or relapse-free survival. Allogeneic stem-cell transplantation is, therefore, a curative treatment for patients with therapy-related myelodysplastic syndrome, conferring a similar long-term survival to that of patients with de novo disease despite higher-risk features. While TP53 alteration was the most common mutation in therapy-related myelodysplastic syndrome, the finding was not detrimental in our case-series.

Comparison of Conditioning with Fludarabine/Busulfan and Fludarabine/Melphalan in Allogeneic Transplantation Recipients 50 Years or Older

The optimal conditioning regimen for elderly patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HCT) remains unclear. We retrospectively analyzed 1607 patients aged 50 years or older with acute myeloid leukemia (AML), acute lymphoblastic leukemia, or myelodysplastic syndrome (MDS) who underwent allo-HCT using fludarabine/busulfan (FB) or fludarabine/melphalan (FM) between 2007 and 2014. We compared the clinical outcomes among FB2 (busulfan at 6.4 mg/kg iv, n = 463), FB4 (busulfan at 12.8 mg/kg iv, n = 721), and FM140 (melphalan at 140 mg/m², n = 423). The nonrelapse mortality (NRM) rates in the FB4 and FM140 groups were higher than that in the FB2 group (hazard ratio [HR], 1.63 [P < .001]; and HR, 1.71 [P < .001], respectively). Conversely, the relapse rates in the FB4 and FM140 groups were lower than that in the FB2 group (HR, .73 [P = .011]; and HR, .56 [P < .001], respectively). There were no significant differences in overall survival (OS) among the FB2, FB4, and FM140 groups. The 3-year OS in patients with high-risk AML and MDS in the FM140 group (37.0% and 60.2%) were superior to those in the FB2 group (24.4% and 45.5%) and the FB4 group (24.6% and 40.6%) (P = .016 and P = .023), whereas there were no differences in OS in the other patients among the 3 groups. In conclusion, the lower rates of relapse in the FB4 and FM140 groups were largely offset by a worse NRM. However, FM140 might be associated with better OS in patients with high-risk AML and MDS.