A long-term follow-up report on allogeneic stem cell transplantation for patients with primary refractory acute myelogenous leukemia: impact of cytogenetic characteristics on transplantation outcome

Understanding blood development and leukemia using sequencing-based technologies and human cell systems

Our current understanding of human hematopoiesis has undergone significant transformation throughout the years, challenging conventional views. The evolution of high-throughput technologies has enabled the accumulation of diverse data types, offering new avenues for investigating key regulatory processes in blood cell production and disease. In this review, we will explore the opportunities presented by these advancements for unraveling the molecular mechanisms underlying normal and abnormal hematopoiesis. Specifically, we will focus on the importance of enhancer-associated regulatory networks and highlight the crucial role of enhancer-derived transcription regulation. Additionally, we will discuss the unprecedented power of single-cell methods and the progression in using in vitro human blood differentiation system, in particular induced pluripotent stem cell models, in dissecting hematopoietic processes. Furthermore, we will explore the potential of ever more nuanced patient profiling to allow precision medicine approaches. Ultimately, we advocate for a multiparameter, regulatory network-based approach for providing a more holistic understanding of normal hematopoiesis and blood disorders.

Chemotherapy or Allogeneic Stem Cell Transplantation as Salvage Therapy for Patients with Refractory Acute Myeloid Leukemia: A Multicenter Analysis

Introduction

The overall outcome of patients with refractory AML (rAML) remains poor. Though allogeneic hematopoietic stem cell transplantation (allo-HSCT) is considered as the only curative therapy, it is routinely recommended only for patients after remission with salvage chemotherapy.

Objective

In this study, we evaluated the impact of salvage chemotherapy or allo-HSCT on the overall outcome in rAML.

Methods

We collected the clinical data of 220 patients from 4 medical centers and performed retrospective analysis of prognosis factors, including salvage chemotherapy, intensity of chemotherapy, and allo-HSCT.

Results

A total of 29 patients received allo-HSCT directly without salvage chemotherapy, 26 patients achieved complete remission (CR) or complete remission with incomplete hematological recovery (CRi) after transplantation and 4-year leukemia-free survival (LFS) and overall survival (OS) were 45.0 ± 10.7 and 51.0 ± 10.6%, respectively. Another 191 patients received salvage chemotherapy and 81 (42.2%) achieved CR or CRi. Thirty-four patients among them underwent subsequent allo-HSCT with 4-year LFS and OS of 46.0 ± 8.8 and 46.2 ± 9.0%. The 4-year LFS and OS in 26 patients who failed to obtain CR or CRi but received allo-HSCT with active disease were 32.9 ± 10.0 and 36.9 ± 10.8%, respectively. For patients who received salvage chemotherapy but not allo-HSCT, few of them became long-term survivors. In multivariate analysis, salvage chemotherapy and the intensity of chemotherapy failed to have significant impact on both OS and LFS. Allo-HSCT was the only prognostic factor for improved OS and LFS in multivariate analysis.

Conclusions

These results indicate the benefit of allo-HSCT in patients with rAML and direct allo-HSCT without salvage chemotherapy could be treatment option.

European LeukemiaNet-defined primary refractory acute myeloid leukemia: the value of allogeneic hematopoietic stem cell transplant and overall response

We sought to appraise the value of overall response and salvage chemotherapy, inclusive of allogeneic hematopoietic stem cell transplant (AHSCT), in primary refractory acute myeloid leukemia (prAML). For establishing consistency in clinical practice, the 2017 European LeukemiaNet (ELN) defines prAML as failure to attain CR after at least 2 courses of intensive induction chemotherapy. Among 60 consecutive patients (median age 63 years) correspondent with ELN-criteria for prAML, salvage was documented in 48 cases, 30/48 (63%) being administered intensive chemotherapy regimens and 2/48 consolidated with AHSCT as first line salvage. 13/48 (27%) attained response: CR, 7/13 (54%), CRi, 2/13 (15%), MLFS, 4/13 (31%). The CR/CRi rate was 9/48 (19%), with CR rate of 7/48 (15%). On univariate analysis, intermediate-risk karyotype was the only predictor of response (44% vs 17% in unfavorable karyotype; P = 0.04). Administration of any higher-dose (>1 g/m²) cytarabine intensive induction (P = 0.50), intensive salvage chemotherapy (P = 0.72), targeted salvage (FLT3 or IDH inhibitors) (P = 0.42), greater than 1 salvage regimen (P = 0.89), age < 60 years (P = 0.30), and de novo AML (P = 0.10) did not enhance response achievement, nor a survival advantage. AHSCT was performed in 12 patients with (n = 8) or without (n = 4) CR/CRi/MLFS. 1/2/5-year overall survival (OS) rates were 63%/38%/33% in patients who received AHSCT (n = 12) vs 27%/0%/0% in those who achieved CR/CRi/MLFS but were not transplanted (n = 5), vs 14%/0%/0% who were neither transplanted nor achieved CR/CRi/MLFS (n = 43; P < 0.001); the median OS was 18.6, 12.6 and 5.6 months, respectively. Although CR/CRi/MLFS bridged to AHSCT (n = 8), appeared to manifest a longer median OS (20 months), vs (13.4 months) for those with no response consolidated with AHSCT (n = 4), the difference was not significant P = 0.47. We conclude AHSCT as indispensable for securing long-term survival in prAML (p = 0.03 on multivariate analysis), irrespective of response achievement.

Type 1 interferon to prevent leukemia relapse after allogeneic transplantation

Augmenting early GVL response by prophylactic type 1 IFN may reduce the rates of leukemic relapse after HCT in very high–risk AML.

Reciprocal toxicities, including acute GVHD and nonrelapse mortality, were not increased after type 1 IFN treatment.

A potent graft-versus-leukemia (GVL) response is crucial in preventing relapse, the major impediment to successful allogeneic hematopoietic cell transplantation (HCT). In preclinical studies, type 1 interferon (IFN-α) enhanced cross-presentation of leukemia-specific antigens by CD8α dendritic cells (DCs) and amplified GVL. This observation was translated into a proof-of-concept phase 1/2 clinical trial with long-acting IFN-α (pegylated IFN-α [pegIFNα]) in patients undergoing HCT for high-risk acute myeloid leukemia (AML). Patients with treatment-resistant AML not in remission or those with poor-risk leukemia were administered 4 dosages of pegIFNα every 14 days beginning at day −1 before HCT. Dose selection was established by adaptive design that continuously assessed the probability of dose-limiting toxicities throughout the trial. Efficacy was evaluated by determining the 6-month incidence of relapse at the maximum tolerated dose (MTD). Thirty-six patients (median age, 60 years) received pegIFNα treatment. Grade 3 or greater severe adverse events occurred in 25% of patients, establishing 180 μg as the MTD. In phase 2, the incidence of relapse was 39% at 6 months, which was sustained through 1-year post-HCT. The incidence of transplant-related mortality was 13%, and severe grade III-IV acute graft-versus-host disease (GVHD) occurred in 11%. Paired blood samples from donors and recipients after HCT revealed elevated levels of type 1 IFN with cellular response, the persistence of cross-presenting DCs, and circulating leukemia antigen-specific T cells. These data suggest that prophylactic administration of pegIFNα is feasible in the peri-HCT period. In high-risk AML, increased toxicity was not observed with preliminary evidence for reduction in leukemia relapse after HCT. This trial was registered at www.clinicaltrials.gov as #NCT02328755.

Detecting and preventing post-hematopoietic cell transplant relapse in AML

PURPOSE OF REVIEW

Relapsed disease is the primary cause of mortality for acute myeloid leukemia (AML) patients after allogeneic hematopoietic cell transplantation (HCT). This review outlines the most recent advances in the detection and prevention of AML relapse following allogeneic HCT.

RECENT FINDINGS

Conventional methods for predicting post-HCT relapse rely on the molecular and cytogenetics features present at diagnosis. These methods are slow to reflect a growing understanding of the molecular heterogeneity of AML and impact of new therapies on post-HCT outcomes. The use of measurable residual disease (MRD) techniques, including multiparameter flow cytometry and molecular testing, may improve the prognostic ability of these models and should be incorporated into post-HCT surveillance whenever possible.In the post-HCT setting, FLT3 inhibitor maintenance data indicate that effective therapies can improve post-HCT outcomes. Maintenance data with DNA methyltransferase inhibitor monotherapy is less compelling and outcomes may improve with combinations. Early interventions directed at preemptive management of MRD may further improve post-HCT outcomes.

SUMMARY

Post-HCT AML relapse prevention has evolved to include more sensitive measures of disease detection and novel therapies that may improve outcomes of poor-risk AML patients. Additional work is needed to maintain this progress.

Comparison of Two Strategies for Prophylactic Donor Lymphocyte Infusion in Patients With Refractory/Relapsed Acute Leukemia

Prophylactic donor lymphocyte infusion (pDLI) could reduce relapse in patients with refractory/relapsed acute leukemia (RRAL) undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT), but optimal timing of pDLI remains uncertain. We compared the outcomes of two strategies for pDLI based on time from transplant and minimal residual disease (MRD) status in patients with RRAL. For patients without grade II–IV acute graft-versus-host disease (aGVHD) on day +60, pDLI was given on day +60 regardless of MRD in cohort 1, and was given on day +90 unless MRD was positive on day +60 in cohort 2. A total of 161 patients with RRAL were enrolled, including 83 in cohort 1 and 78 in cohort 2. The extensive chronic GVHD (cGVHD) incidence in cohort 2 was lower than that in cohort 1 (10.3% vs. 27.9%, P = 0.006) and GVHD-free/relapse-free survival (GRFS) in cohort 2 was superior to that in cohort 1 (55.1% vs. 41.0%, P = 0.042). The 2-year relapse rate, overall and leukemia-free survival were comparable between the two cohorts (29.0% vs. 28.2%, P = 0.986; 63.9% vs. 64.1%, P = 0.863; 57.8% vs. 61.5%, P = 0.666). Delaying pDLI to day +90 based on MRD for patients with RRAL undergoing allo-HSCT could lower extensive cGVHD incidence and improve GRFS without increasing incidence of leukemia relapse compared with pDLI on day +60.

Allogeneic Hematopoietic Cell Transplantation for Adolescent and Young Adult Patients with Acute Myeloid Leukemia

Limited data exist regarding the outcomes of allogeneic hematopoietic cell transplantation (allo-HCT) among adolescent and young adult (AYA) patients with acute myeloid leukemia (AML). Here we analyzed the features and outcomes of AYA patients with AML who had achieved complete remission (CR) and those who had not (non-CR) at allo-HCT. We retrospectively analyzed 2350 AYA patients with AML who underwent allo-HCT with a myeloablative conditioning regimen and who were consecutively enrolled in the Japanese nationwide HCT registry. The difference in overall survival (OS) between younger (age 16 to 29 years) and older AYA (age 30 to 39 years) patients in CR at transplantation was not significant (70.2% versus 71.7% at 3 years; P = .62). Meanwhile, this difference trended toward a statistical significance between younger and older AYA patients in non-CR at transplantation (39.5% versus 34.3% at 3 years; P = .052). In AYA patients in CR and non-CR, the age at transplantation did not affect relapse or nonrelapse mortality (NRM). In AYA patients in CR, no difference in OS was observed between those who received total body irradiation (TBI) and those who did not (71.1% versus 70.5% at 3 years; P = .43). AYA patients who received TBI-based conditioning had a significantly lower relapse rate and higher NRM than those who underwent non-TBI-based conditioning (relapse: 19.8% versus 24.1% at 3 years [P = .047]; NRM: 14.7% versus 11.1% at 3 years [P = .021]). In contrast, among the non-CR patients, there were no differences between the TBI and non-TBI groups with respect to OS (P = .094), relapse (P = .83), and NRM (P = .27). Our data indicate that outcomes may be more favorable in younger AYA patients than in older AYA patients in non-CR at transplantation, and that outcomes of TBI-based conditioning could be comparable to those of non-TBI-based conditioning for AYA patients.

Myeloablative Conditioning for Allogeneic Transplantation Results in Superior Disease-Free Survival for Acute Myelogenous Leukemia and Myelodysplastic Syndromes with Low/Intermediate but not High Disease Risk Index: A Center for International Blood and Marrow Transplant Research Study

Compared with reduced-intensity conditioning (RIC), myeloablative conditioning (MAC) is generally associated with lower relapse risk after allogeneic hematopoietic cell transplantation (HCT) for acute myelogenous leukemia (AML) and myelodysplastic syndromes (MDS). However, disease-specific risk factors in AML/MDS can further inform when MAC and RIC may yield differential outcomes. We analyzed HCT outcomes stratified by the Disease Risk Index (DRI) in 4387 adults (age 40 to 65 years) to identify the impact of conditioning intensity. In the low/intermediate-risk DRI cohort, RIC was associated with lower nonrelapse mortality (NRM) (hazard ratio [HR], .74; 95% confidence interval [CI], .62 to .88; P < .001) but significantly greater relapse risk (HR, 1.54; 95% CI, 1.35 to 1.76; P < .001) and thus inferior disease-free survival (DFS) (HR, 1.19; 95% CI, 1.07 to 1.33; P = .001). In the high/very high-risk DRI cohort, RIC was associated with marginally lower NRM (HR, .83; 95% CI, .68 to 1.00; P = .051) and significantly higher relapse risk (HR, 1.23; 95% CI, 1.08 to 1.41; P = .002), leading to similar DFS using either RIC or MAC. These data support MAC over RIC as the preferred conditioning intensity for patients with AML/MDS with low/intermediate-risk DRI, but with a similar benefit as RIC in high/very high-risk DRI. Novel MAC regimens with less toxicity could benefit all patients, but more potent antineoplastic approaches are needed for the high/very-high risk DRI group.

Clinical Benefits of Preconditioning Intervention in Patients with Relapsed or Refractory Acute Myelogenous Leukemia Who Underwent Allogeneic Hematopoietic Cell Transplantation: A Kanto Study of Group for Cell Therapy Multicenter Analysis

A multicenter retrospective study was conducted to evaluate the clinical significance of preconditioning intervention (PCI) before allogeneic hematopoietic cell transplantation (HCT) in patients with acute myelogenous leukemia (AML) not in remission. The study cohort consisted of 519 patients classified according to the intensity (intensive/moderate) of PCI and their response to PCI. The group treated with PCI had higher blast counts in the peripheral blood (PB) and had a lower overall survival (OS) rate (P < .001) and higher nonrelapse mortality (NRM) rate (P = .035) compared with those without PCI (no PCI group). Approximately 40% of the patients (68 of 236) achieved a good response to PCI (good PCI group), and those patients had lower blast counts in the PB compared with the group with poor response to PCI (poor PCI group). OS in the good PCI group was comparable to that in the no PCI group and significantly better than that in the poor PCI group (hazard ratio, .54; 95% confidence interval, .39 to .77; P < .001). However, OS was significantly lower in patients with intensive/moderate PCI compared with the no PCI group. These results suggest that PCI increases NRM without decreasing the post-transplantation relapse rate, but may be beneficial for patients with lower blast counts in PB irrespective of its intensity.

Novel Approach for Bone Marrow Transplantation Conditioning in Acute Myelogenous Leukemia not Responding to the Induction Therapy Using Etoposide Carried in Lipid Core Nanoparticles: A Pilot Clinical Study

Allogeneic hematopoietic cell transplantation (HCT) is the treatment of choice for acute myelogenous leukemia (AML) not responding to induction therapy. It is a therapeutic choice for the blast phase of chronic myelogenous leukemia (CML-BP) in patients failing to respond to tyrosine kinase inhibitors (TKIs). Lipid core nanoparticles (LDEs) concentrate severalfold more in blast cells than in corresponding normal cells. Incorporation of anticancer drugs to LDE formulations increases the pharmacologic action and decreases the toxicity. We tested a drug-targeting system, LDE-etoposide plus total body irradiation (TBI; 1200 cGy dose), in 13 patients with AML not responding to the induction therapy and in 2 patients with CML-BP refractory to second-generation TKIs. The mean patient age was 46.7 years (range, 22 to 66 years). The LDE-etoposide dose was escalated at 20, 30, 40, 50, and 60 mg/kg. No patients developed grade 4 or 5 toxicity; however, mucositis grade 3 occurred in 6 patients, 3 patients experienced diarrhea, and 1 patient had an elevated total bilirubin level. No deaths were related to conditioning. All patients were successfully engrafted. The median times to neutrophil and platelet engraftment were 20 ± 5 days and 16 ± 4 days, respectively. Five patients (33.4%) had acute graft-versus-host-disease (GVHD), including 4 grade I, and 1 with grade II, and 8 patients (57.1%) had moderate-to-severe chronic GVHD. This pilot study shows the potential of LDE-etoposide plus TBI as an HCT conditioning regimen in AML patients not responding to the induction and refractory therapies for CML-BP patient. These findings pave the way for subsequent larger clinical trials.

The Predicted Indirectly Recognizable HLA Epitopes (PIRCHE) Score for HLA Class I Graft-versus-Host Disparity Is Associated with Increased Acute Graft-versus-Host Disease in Haploidentical Transplantation with Post-Transplantation Cyclophosphamide

The Predicted Indirectly Recognizable HLA Epitopes (PIRCHE) score quantifies the number of PIRCHEs in patient-donor pairs and represents an in silico measure of indirect alloreactivity. This biologic process is defined as T cell recognition of epitopes derived from mismatched, allogeneic HLA peptides that are subsequently presented by shared HLA molecules. Its association with clinical outcome has not been examined in haploidentical hematopoietic cell transplantation (haplo-HCT) with post-transplantation cyclophosphamide (PTCy). We hypothesized that the PIRCHE score (PS) would correlate with indirect alloreactivity and predict graft-versus-host disease (GVHD) risk and the incidence of relapse after haplo-HCT with PTCy. We retrospectively analyzed 148 patients who underwent peripheral blood stem cell T cell-replete haplo-HCT with PTCy at a single center between 2009 and 2016. For each patient-donor pair, the PS was calculated using the PIRCHE online matching tool. PSs were categorized by class and vector. The median class I graft-versus-host (GVH) PS was 11 (range, 0 to 56), and the median class I host-versus-graft (HVG) PS was 10 (range, 0 to 51). Class I GVH PS was associated with increased risk of grade II-IV acute GVHD (adjusted hazard ratio, 1.03 per PS unit increase; 95% confidence interval, 1.01 to 1.05; P= .008) but not of chronic GVHD or relapse. Our data show that use of the PS is a novel strategy for predicting clinical outcome in haplo-HCT; further studies using registry data and prospective cohorts are warranted to validate these findings.

HLA epitope mismatch in haploidentical transplantation is associated with decreased relapse and delayed engraftment

HLA disparity is traditionally measured at the antigen or allele level, and its impact on haploidentical hematopoietic cell transplantation (haplo-HCT) with high-dose posttransplant cyclophosphamide (PTCy) is unclear. To the best of our knowledge, the relationship between HLA eplet-derived epitope mismatch (EM) and clinical outcome has not been examined in haplo-HCT. We retrospectively analyzed 148 patients who received a peripheral blood, T-cell-replete haplo-HCT with PTCy at a single center. HLA EM was quantified using an HLAMatchmaker-based method and was stratified by class and vector. The primary outcome was incidence of relapse. The total number of mismatched epitopes (MEs) per patient-donor pair in our patient population ranged from 0 to 51 (median, 24) in the graft-versus-host (GVH) direction and 0 to 47 (median, 24) in the host-versus-graft (HVG) direction. Higher HLA class II EM in the GVH direction was associated with a significantly reduced risk of relapse (adjusted hazard ratio [HR], 0.952 per ME; P = .002) and improved relapse-free survival (adjusted HR, 0.974 per ME; P = .020). Higher HLA class II EM in the HVG direction was associated with longer time to neutrophil (adjusted HR, 0.974 per ME; P = .013) and platelet (adjusted HR, 0.961 per ME; P = .001) engraftment. In peripheral blood haplo-HCT patients, increased HLA EM was associated with a protective effect on the risk of relapse in the GVH direction but a negative effect on time to count recovery in the HVG direction. HLA EM based on the HLA Matchmaker represents a novel strategy to predict clinical outcome in haplo-HCT.

Prognostic index for patients with relapsed or refractory acute myeloid leukemia who underwent hematopoietic cell transplantation: a KSGCT multicenter analysis

A multicenter retrospective study was performed to explore a prognostic scoring index in order to identify a population who are least likely to benefit from allogeneic hematopoietic cell transplantation (HCT) in patients with relapsed or refractory acute myeloid leukemia (AML). The cohort included 519 patients with AML, who received HCT between 2005 and 2015 at a status of relapse or primary induction failure. Multivariate analysis demonstrated five independent predictors for OS, including C-reactive protein ≥ 1 mg/dL, peripheral blood blast fraction ≥ 20%, poor-risk karyotype, performance status ≥ 2, and bone marrow unrelated donor as a stem cell source. A prognostic scoring index was explored based on these predictors, and successfully separated the cohort into four groups. At 2 years, OS was 47%, 24%, 8%, and 0% for Good (Score 0, 1: n = 118), Intermediate-1 (Score 2: n = 75), Intermediate-2 (Score 3: n = 39), and Poor (Score 4: n = 24), respectively (P < 0.001). The predicting value of the index was confirmed in a validation cohort. Although a further validation study is warranted, the scoring index may be useful to predict survival and to identify the population with the lowest survival prior to HCT in patients with relapsed or refractory AML.

Proteomic Profiling of Signaling Networks Modulated by G-CSF/Plerixafor/Busulfan-Fludarabine Conditioning in Acute Myeloid Leukemia Patients in Remission or with Active Disease prior to Allogeneic Stem Cell Transplantation

To characterize intracellular signaling in peripheral blood (PB) cells of acute myeloid leukemia (AML) patients undergoing pretransplant conditioning with CXCR4 inhibitor plerixafor, granulocyte colony-stimulating factor (G-CSF), and busulfan plus fludarabine (Bu+Flu) chemotherapy, we profiled 153 proteins in 33 functional groups using reverse phase protein array. CXCR4 inhibition mobilized AML progenitors and clonal AML cells, and this was associated with molecular markers of cell cycle progression. G-CSF/plerixafor and G-CSF/plerixafor/Bu+Flu modulated distinct signaling networks in AML blasts of patients undergoing conditioning with active disease compared to nonleukemic PB cells of patients in remission. We identified AML-specific proteins that remained aberrantly expressed after chemotherapy, representing putative chemoresistance markers in AML.

Discovery of donor genotype associated with long-term survival of patients with hematopoietic stem cell transplantation in refractory acute myeloid leukemia

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been the only treatment option for acute myeloid leukemia (AML) refractory to induction chemotherapy, with only 10-20% of patients achieving long-term survival. Certain donor genotypes may confer leukemia-clearing effects after allo-HSCT. We performed whole-exome sequencing of five pairs of the germ lines in AML patients who achieved long-term remission after allo-HSCT and in their donors, and found two significant variants: EGFR c.2982C > T and CDH11 c.945G > A. To validate the protective effects of these leukemia-clearing genotypes (LCGs), AML patients who received allo-HSCT in a complete-remission status were also analyzed. Twenty-two of 96 donors (22.9%) had LCGs in their genomes, and overall survival was significantly longer in patients who received allo-HSCT from donors with germ-line LCGs (hazard ratio=0.47, 95% confidence interval=0.24-0.94, p = .033). These findings indicate that donor germ-line LCGs have phenotypically leukemia-clearing effects and are biomarkers for predicting clinical outcomes in allogeneic transplantation in AML patients.

Haploidentical versus unrelated allogeneic stem cell transplantation for relapsed/refractory acute myeloid leukemia: a report on 1578 patients from the Acute Leukemia Working Party of the EBMT

Primary refractory or relapsed acute myeloid leukemia is associated with a dismal prognosis. Allogeneic stem cell transplantation is the only therapeutic option that offers prolonged survival and cure in this setting. In the absence of a matched sibling donor, transplantation from unrelated 10/10 HLA allele-matched or 9/10 HLA allele-mismatched donors and haploidentical donors are potential alternatives. The current study aimed to compare the outcomes of acute myeloid leukemia patients with active disease who received allogeneic stem cell transplantation from a haploidentical donor with post-transplant cyclophosphamide (n=199) versus an unrelated 10/10-matched donor (n=1111) and versus an unrelated 9/10-mismatched donor (n=383) between 2007 and 2014 and who were reported to the European Society for Blood and Marrow Transplantation registry. Propensity score weighted analysis was conducted in order to control for disease risk imbalances between the groups. The leukemia-free survival rates at 2 years of recipients of grafts from a haploidentical donor, an unrelated 10/10-matched donor and an unrelated 9/10-mismatched donor were 22.8%, 28% and 22.2%, respectively (P=NS). In multivariate analysis, there were no significant differences in leukemia-free survival, overall survival, relapse incidence, non-relapse mortality, or graft-versus-host-disease-free relapse-free survival between the three groups. Two predictive factors were associated with a higher relapse incidence: transplantation during first or second relapse compared to primary refractory acute myeloid leukemia and poor cytogenetics. Allogeneic stem cell transplantation may rescue about 25% of acute myeloid leukemia patients with active disease. Importantly, the outcomes of transplants from haploidentical donors were comparable to those from 10/10-matched and 9/10-mismatched unrelated donors. Therefore, a haploidentical donor is a valid option for acute myeloid leukemia patients with active disease.

Clinical outcome of FLAG-IDA chemotherapy sequential with Flu-Bu3 conditioning regimen in patients with refractory AML: a parallel study from Shanghai Institute of Hematology and Institut Paoli-Calmettes

The purpose of the study was to evaluate the feasibility of conditioning regimen with sequential chemotherapy (FLAG-IDA), followed by Fludarabine (5 days) + Busulfan (3 days) by parallel analysis of patients with refractory acute myeloid leukemia (AML) from two transplantation centers in China and France. A total of 47 refractory AML with median bone marrow blast of 35% (1–90%) and median age at 42 years (16–62) were enrolled. Thirteen patients received peripheral stem cell transplantation (HSCT) from HLA-matched sibling donor, while 18 and 16 from unrelated or haplo-identical donors, respectively. With a median follow-up of 24.3 months (1–70), 13 patients relapsed at a median time of 5.1 months (2.2–18.0) and 24 patients died due to relapse (n = 12) or non-relapsed mortality (NRM, n = 12). The estimated 3-year RR and NRM were 33.5 ± 5.7% and 25.7 ± 4.2%, respectively. The estimated 3-year overall survival (OS) and event-free survival (EFS) were 43.8 ± 7.8% and 42.3 ± 7.8%. In multivariate analysis, age (<40) and low bone marrow blast were associated with better EFS, while no difference was observed between the two centers. The patients enrolled in study were unselected, representing typical patients' population of refractory AML, and primary data demonstrated the feasibility of sequential conditioning regimen.

Efficacy of haploidentical hematopoietic stem cell transplantation compared to HLA-matched transplantation for primary refractory acute myeloid leukemia

Newly diagnosed acute myeloid leukemia (AML) failed to achieve complete remission after two courses of intensive chemotherapy. This was considered as primary refractory AML (PRR-AML), and still has a dismal prognosis. Allogeneic hematopoietic stem cell transplantation could be the only cure for these patients. However, the role of haploidentical hematopoietic stem cell transplantation (HID-HCT) for PRR-AML is still undetermined. We retrospectively analyzed the outcomes of 45 adult patients with PRR-AML who underwent HID-HCT, and compared it with the result of 53 patients who received HLA-matched related or unrelated donor transplantation (MD-HCT) during the same treatment period. The 3-year overall survival (OS), leukemia-free survival (LFS), cumulative incidence of relapse (CIR), and non-relapse mortality (NRM) rates in the HID-HCT group were 19.0, 16.5, 70.0, and 35.2%, respectively, but showed no significant differences from the results of MD-HCT. Multivariate analysis showed that complex karyotype with del(7) and time > 6 months from diagnosis to transplantation were associated with lower OS and LFS, and chronic GVHD demonstrated better OS and LFS in the entire cohort. Complex karyotype with del(7) was related with higher CIR and chronic GVHD with lower CIR. In conclusion, HID-HCT could be an alternative treatment strategy to improve the long-term survival in PRR-AML adult patients who have no HLA-matched donors.

High-dose melphalan-based sequential conditioning chemotherapy followed by allogeneic haematopoietic stem cell transplantation in adult patients with relapsed or refractory acute myeloid leukaemia

Considering the unsatisfactory results of salvage therapies for patients with relapsed/refractory acute myeloid leukaemia (R/R-AML), their value before allogeneic haematopoietic stem cell transplantation (HSCT) remains questionable. However, direct allogeneic HSCT following established conditioning regimens applied in patients with R/R-AML during active disease has been equally disappointing. In this retrospective observational study, high-dose melphalan, as part of a sequential preparative regimen, followed by a total body irradiation (4 × 2 Gy)-based or a treosulfan-based dose-adapted conditioning therapy for allogeneic HSCT was administered to 292 adult patients (median age 56 years, range 17-74) with primary refractory (144 patients), secondary refractory (97 patients) or relapsed AML (51 patients). Overall survival rates at 3 years were 34%, 29% and 41%, respectively. Risk factors associated with an inferior survival were higher age, transplantation from a human leucocyte antigen-mismatched donor and high disease burden. Patients transplanted with blast infiltration <20% showed a notable survival rate of 51% at 3 years. In particular, patients with primary refractory AML showed a more favourable outcome when transplanted early during their disease course. Thus, high-dose melphalan-based sequential conditioning chemotherapy followed by an allogeneic HSCT is feasible and enables long-term remission to be achieved in a substantial proportion of patients with active R/R-AML.

Sequential intensified conditioning followed by prophylactic DLI could reduce relapse of refractory acute leukemia after allo-HSCT

The major obstacle is leukemia relapse for refractory leukemia undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). We previously introduced a strategy of sequential intensified conditioning and early rapid immunosupressant withdrawal for refractory leukemia undergoing allo-HSCT, with 5-year overall survival (OS) and 3-year relapse rate of 44.6% and 33.3%. To reduce leukemia relapse, prophylactic donor lymphocyte infusion (DLI) was administered based on our historical strategy. A total of 153 refractory advanced acute leukemia patients were enrolled in this prospective study. According to the availability of donor lymphocytes and the criteria for DLI, 144 patients surviving day +60 were divided into two groups (80 DLI versus 64 non-DLI). The relapse rate was less and OS was better in patients receiving DLI than in those not receiving DLI (22.7% vs 33.9%, P=0.048; 58.1% vs 54.9%, P=0.043). The non-relapse mortality (NRM) was similar between DLI and non-DLI groups (P=0.104). Overall, the 5-year overall and disease-free survival post-transplantation were 51.1%±5.7% and 49.2%±5.3%. The 5-year relapse rate and NRM were 27.3%±4.4% and 29.7%±5.3%. Multivariate analysis revealed that lower bone marrow blasts on day 0, DLI and chronic graft-versus-host disease were associated with less relapse and better OS. The strategy of sequential intensified conditioning followed by early immunosupressant withdrawal and DLI could reduce relapse of refractory acute leukemia after allo-HSCT and improve survival.

Durable graft-versus-leukaemia effects without donor lymphocyte infusions - results of a phase II study of sequential T-replete allogeneic transplantation for high-risk acute myeloid leukaemia and myelodysplasia

Allogeneic haematopoietic stem-cell transplantation remains the only curative treatment for relapsed/refractory acute myeloid leukaemia (AML) and high-risk myelodysplasia but has previously been limited to patients who achieve remission before transplant. New sequential approaches employing T-cell depleted transplantation directly after chemotherapy show promise but are burdened by viral infection and require donor lymphocyte infusions (DLI) to augment donor chimerism and graft-versus-leukaemia effects. T-replete transplantation in sequential approaches could reduce both viral infection and DLI usage. We therefore performed a single-arm prospective Phase II clinical trial of sequential chemotherapy and T-replete transplantation using reduced-intensity conditioning without planned DLI. The primary endpoint was overall survival. Forty-seven patients with relapsed/refractory AML or high-risk myelodysplasia were enrolled; 43 proceeded to transplantation. High levels of donor chimerism were achieved spontaneously with no DLI. Overall survival of transplanted patients was 45% and 33% at 1 and 3 years. Only one patient developed cytomegalovirus disease. Cumulative incidences of treatment-related mortality and relapse were 35% and 20% at 1 year. Patients with relapsed AML and myelodysplasia had the most favourable outcomes. Late-onset graft-versus-host disease protected against relapse. In conclusion, a T-replete sequential transplantation using reduced-intensity conditioning is feasible for relapsed/refractory AML and myelodysplasia and can deliver graft-versus-leukaemia effects without DLI.

Mesenchymal stromal cells contribute to quiescence of therapy-resistant leukemic cells in acute myeloid leukemia

OBJECTIVE

Persistence of leukemic cells after induction therapy has been shown to correlate with poor survival in acute myeloid leukemia (AML). In this study, we tested if human mesenchymal stromal cells (hMSCs) have protective effects on leukemic cells undergoing chemotherapy.

METHODS

Persistent disease was used as marker to identify cases with therapy-resistant leukemic cells in 95 patients with AML. Immunophenotyping, cell cycle, and apoptosis assays were assessed by flow cytometry. AML coculture studies were performed with hMSC of healthy donors.

RESULTS

Samples from patients with persistent disease had increased fractions of CD34⁺ CD38^- and quiescent leukemic cells. Comparison of sample series collected at time points of diagnosis and blast persistence showed a relative therapy resistance of quiescent leukemic cells. Consistent with these observations, relapsed disease always displayed higher proportions of quiescent cells compared to samples of first diagnosis suggesting that quiescence is an important therapy escape mechanism of resistant cells. Co-culture studies demonstrated that hMSC protect leukemic cells from the effect of AraC treatment by enriching for quiescent cells, mimicking the effects observed in patients. This effect was even detectable when no direct stromal contact was established.

CONCLUSIONS

Our data suggest that hMSC contribute to quiescence and therapy resistance of persistent AML cells.

Comparison of matched sibling donors versus unrelated donors in allogeneic stem cell transplantation for primary refractory acute myeloid leukemia: a study on behalf of the Acute Leukemia Working Party of the EBMT

BACKGROUND

Primary refractory acute myeloid leukemia (PRF-AML) is associated with a dismal prognosis. Allogeneic stem cell transplantation (HSCT) in active disease is an alternative therapeutic strategy. The increased availability of unrelated donors together with the significant reduction in transplant-related mortality in recent years have opened the possibility for transplantation to a larger number of patients with PRF-AML. Moreover, transplant from unrelated donors may be associated with stronger graft-mediated anti-leukemic effect in comparison to transplantations from HLA-matched sibling donor, which may be of importance in the setting of PRF-AML.

METHODS

The current study aimed to address the issue of HSCT for PRF-AML and to compare the outcomes of HSCT from matched sibling donors (n = 660) versus unrelated donors (n = 381), for patients with PRF-AML between 2000 and 2013. The Kaplan-Meier estimator, the cumulative incidence function, and Cox proportional hazards regression models were used where appropriate.

RESULTS

HSCT provide patients with PRF-AML a 2-year leukemia-free survival and overall survival of about 25 and 30%, respectively. In multivariate analysis, two predictive factors, cytogenetics and time from diagnosis to transplant, were associated with lower leukemia-free survival, whereas Karnofsky performance status at transplant ≥90% was associated with better leukemia-free survival (LFS). Concerning relapse incidence, cytogenetics and time from diagnosis to transplant were associated with increased relapse. Reduced intensity conditioning regimen was the only factor associated with lower non-relapse mortality.

CONCLUSIONS

HSCT was able to rescue about one quarter of the patients with PRF-AML. The donor type did not have any impact on PRF patients' outcomes. In contrast, time to transplant was a major prognostic factor for LFS. For patients with PRF-AML who do not have a matched sibling donor, HSCT from an unrelated donor is a suitable option, and therefore, initiation of an early search for allocating a suitable donor is indicated.

Allogeneic hematopoietic cell transplantation for primary refractory acute lymphoblastic leukemia: A report from the Acute Leukemia Working Party of the EBMT

BACKGROUND

Patients with primary refractory acute lymphoblastic leukemia (PREF ALL) who fail to achieve a complete remission (CR) after ≥2 courses of chemotherapy have a dismal prognosis without undergoing allogeneic hematopoietic cell transplantation (HCT). To the authors' knowledge, there currently are no data regarding factors influencing transplantation outcomes.

METHODS

The authors retrospectively studied outcomes of transplantation for cases of PREF ALL reported to European Society for Blood and Marrow Transplantation registry. Eligibility criteria for the current analysis included adult patients who underwent their first HCT for PREF ALL between 2000 and 2012. PREF disease was defined as the failure to achieve a morphological CR after ≥2 courses of induction chemotherapy.

RESULTS

Data regarding 86 adult patients were analyzed. With a median follow-up of 106 months, the probability of survival was 36% at 2 years and 23% at 5 years. The probability of leukemia-free survival was 28% and 17%, respectively, and the probability of nonrecurrence mortality was 20% and 29%, respectively, at 2 years and 5 years. For 66 patients who achieved a CR (77%), the survival at 2 years and 5 years was 36% and 29%, respectively. In multivariate analysis, use of total body irradiation was found to be associated with improved survival. Total body irradiation and infusion of female hematopoietic cells into male recipients was associated with improved leukemia-free survival. These findings were incorporated into a scoring system that identified 3 groups (those with 2, 1, or no prognostic factors) with survival rates of 57%, 22%, and 8%, respectively.

CONCLUSIONS

Although overall these patients would clearly benefit from the introduction of novel antileukemic therapies, the data from the current study support the use of allogeneic HCT in selected patients with PREF ALL. Cancer 2017;123:1965-1970. © 2017 American Cancer Society.

Salvage therapy for acute chemorefractory leukemia by allogeneic stem cell transplantation: the Korean experience

Little is known about the characteristics that make patients with acute leukemia suitable for undergoing salvage therapy by allogeneic hematopoietic stem cell transplantation (allo-HSCT). Here, we analyzed the clinical outcomes of 223 patients with acute leukemia who underwent allo-HSCT while not in complete remission (CR). The primary end points were overall survival (OS) and CR rate. CR was achieved in 79.8% of patients after allo-HSCT. Acute graft-versus-host disease (GVHD) was significantly associated with CR (P = 0.045). During a median follow-up of 30.1 months, the median OS was 6.1 months. OS was significantly longer in patients with good or standard risk cytogenetic characteristics than in those with poor risk cytogenetic characteristics (P = 0.029, P = 0.030, respectively). Patients who received allo-HSCT from a matched sibling donor had better survival than those with unrelated donors (P = 0.015). Primary chemorefractoriness was not associated with poor survival (P = 0.071). The number of chemotherapies before allo-HSCT was significantly correlated with outcome (P = 0.006). Chronic GVHD was a strong predictor of a longer OS (P = 0.025). In conclusion, survival of patients with primary chemorefractory acute leukemia is not lower when treated upfront with allo-HSCT. Hence, allo-HSCT should be actively considered in such patients. Acute and chronic GVHD is associated with better outcomes patients with acute leukemia who have undergone allo-HSCT and not achieved CR.

Total Body Irradiation without Chemotherapy as Conditioning for an Allogeneic Hematopoietic Cell Transplantation for Adult Acute Myeloid Leukemia

Current therapies for acute myeloid leukemia (AML), failing induction, are rarely effective. We report our experience in 4 patients with AML who received 16 Gy TBI prior to allogeneic hematopoietic cell transplantation (alloHCT), between June 2010 and May 2011. Patients were 20 to 55 years of age, 2 with relapsed disease and 2 with AML failing induction. An HLA-matched graft from related or unrelated donor was infused on day 0. All but one, who received a CD34⁺-selected graft, received methotrexate and tacrolimus +/- antithymocyte globulin, as GVHD prophylaxis. The other patient received tacrolimus alone. Neutrophil and platelet engraftment occurred at a median of 18 and 14 days, respectively. Patients were discharged at a median of 28 days. There were no unexpected toxicities in the first 30 days. One patient had cytomegalovirus (CMV) viremia and anorexia, at two months. One patient had grade 2 acute GVHD of the skin. One patient developed chronic GVHD of the eyes, mouth, skin, joints, and lung at 4 months. Two patients died from relapse of their leukemia at days 65 and 125. Two patients remain in remission beyond day 1500. 16 Gy TBI followed by an alloHCT for AML, failing induction, is feasible and tolerable.

Sequential regimen of clofarabine, cytosine arabinoside and reduced-intensity conditioned transplantation for primary refractory acute myeloid leukemia

The prognosis of patients with acute myeloid leukemia in whom primary treatment fails remains very poor. In order to improve such patients' outcome, we conducted a phase 2, prospective, multicenter trial to test the feasibility of a new sequential regimen, combining a short course of intensive chemotherapy and a reduced intensity-conditioning regimen, before allogeneic stem-cell transplantation. Twenty-four patients (median age, 47 years) with acute myeloid leukemia in primary treatment failure were included. Cytogenetic risk was poor in 15 patients (62%) and intermediate in nine (38%). The sequential regimen consisted of clofarabine (30 mg/m²/day) and cytosine arabinoside (1 g/m²/day) for 5 days, followed, after a 3-day rest, by reduced-intensity conditioning and allogeneic stem-cell transplantation combining cyclophosphamide (60 mg/kg), intravenous busulfan (3.2 mg/kg/day) for 2 days and anti-thymocyte globulin (2.5 mg/kg/day) for 2 days. Patients in complete remission at day +120 received prophylactic donor lymphocyte infusion. Eighteen patients (75%) achieved complete remission. With a median follow-up of 24.6 months, the Kaplan-Meier estimate of overall survival was 54% (95% CI: 33-71) at 1 year and 38% (95% CI: 18-46) at 2 years. The Kaplan-Meier estimate of leukemia-free survival was 46% (95% CI: 26-64) at 1 year and 29% (95% CI: 13-48) at 2 years. The cumulative incidence of non-relapse mortality was 8% (95% CI: 1-24) at 1 year and 12% (95% CI: 3-19) at 2 years. Results from this phase 2 prospective multicenter trial endorsed the safety and efficacy of a clofarabine-based sequential reduced-toxicity conditioning regimen, which warrants further investigation. This study was registered at www.clinicaltrials.gov, identifier number: NCT01188174.

An operational definition of primary refractory acute myeloid leukemia allowing early identification of patients who may benefit from allogeneic stem cell transplantation

Up to 30% of adults with acute myeloid leukemia fail to achieve a complete remission after induction chemotherapy - termed primary refractory acute myeloid leukemia. There is no universally agreed definition of primary refractory disease, nor have the optimal treatment modalities been defined. We studied 8907 patients with newly diagnosed acute myeloid leukemia, and examined outcomes in patients with refractory disease defined using differing criteria which have previously been proposed. These included failure to achieve complete remission after one cycle of induction chemotherapy (RES), less than a 50% reduction in blast numbers with >15% residual blasts after one cycle of induction chemotherapy (REF1) and failure to achieve complete remission after two courses of induction chemotherapy (REF2). 5-year overall survival was decreased in patients fulfilling any criteria for refractory disease, compared with patients achieving a complete remission after one cycle of induction chemotherapy: 9% and 8% in patients with REF1 and REF2 versus 40% (P<0.0001). Allogeneic stem cell transplantation improved survival in the REF1 (HR 0.58 (0.46-0.74), P=0.00001) and REF2 (HR 0.55 (0.41-0.74), P=0.0001) cohorts. The utilization of REF1 criteria permits the early identification of patients whose outcome after one course of induction chemotherapy is very poor, and informs a novel definition of primary refractory acute myeloid leukemia. Furthermore, these data demonstrate that allogeneic stem cell transplantation represents an effective therapeutic modality in selected patients with primary refractory acute myeloid leukemia.

Outcome of myeloablative allogeneic peripheral blood hematopoietic stem cell transplantation for refractory/relapsed AML patients in NR status

To further find effective method to improve the long term survival of refractory or relapsed acute myeloid leukemia (AML) patients, we retrospectively analyzed the outcomes of myeloablative hematopoietic stem cell transplantation (HSCT) for 133 consecutive patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) therapy related AML(t-AML) in not remission status. The overall 3-year OS and DFS were 40.9% and 35.6% respectively. The variables associated with improved long term DFS were a bone marrow blast cell count less than 20% and an intensified conditioning regimen. In addition, the t-AML group had higher rates of relapse and III-IV acute GVHD than the primary AML group. The unrelated donor group had similar OS and DFS with sibling groups. Our study suggested that decreasing bone marrow blast cell counts before HSCT and strengthening the conditioning regimen may improve long-term DFS for refractory/relapsed AML patients, and unrelated donor group can get similar effect when compared to the sibling group.

Allogeneic Transplantation for Unfavorable-Risk Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a complex, heterogeneous disorder that can have devastating effects. Although control of AML can be attained with various induction regimens, long-term cure is much more difficult to maintain. This is understated in patients with unfavorable-risk AML, who are usually older and have prior myeloid and/or therapy-related disease and more challenges in curing this disease.

Outcome of children with acute myeloid leukaemia (AML) experiencing primary induction failure in the AIEOP AML 2002/01 clinical trial

Paediatric patients with acute myeloid leukaemia (AML) who fail induction due to primary resistance to chemotherapy account for a significant proportion of cases and have a particularly dismal prognosis. We report the clinical and biological data, and final outcome of 48 paediatric patients with primary-resistant AML enrolled in the Associazione Italiana di Ematologia e Oncologia Pediatrica AML 2002/01 clinical trial. These patients had a significantly higher white blood cell count at diagnosis compared to other AML patients. Cytogenetic and molecular features did not differ between patients with primary induction failure and patients allocated to the high-risk group. For the whole patient population, the probability of overall survival, event-free survival (EFS) and disease-free survival (DFS) was 21·8% ± 6·2, 20·4% ± 5·9, and 49·5% ± 11·3, respectively. Twenty-eight (58%) patients received haematopoietic stem cell transplantation (HSCT); 3 were autologous and 25 were allogeneic. Patients who underwent HSCT had improved EFS (31·2% vs. 5%, P < 0·0001). Only one of the 20 patients who did not receive HSCT is alive and disease free. The 19 patients in complete remission at time of HSCT showed significantly better DFS than the 9 with active disease (46% vs. 0%, P = 0·02). This study represents one of the largest series with long-term follow up of paediatric AML patients with primary refractory disease. Children who underwent transplantation had an encouraging long-term outcome. Disease recurrence remains the major cause of treatment failure; a better understanding of the disease biology is desirable to develop more effective treatment strategies.

Busulfan and fludarabine conditioning regimen given at hematological nadir of cytoreduction fludarabine, cytarabine, and idarubicin chemotherapy in patients with refractory acute myeloid leukemia undergoing allogeneic stem cell transplantation: a single arm pilot consort study

To improve the outcome of allogeneic stem cell transplantation in refractory acute myeloid leukemia (AML), we conducted a single-arm phase II clinical trial to evaluate the efficacy and feasibility of conditioning regimen following cytoreduction chemotherapy with 7-day interval. Adult patients with refractory AML were enrolled in the study and received fludarabine, cytarabine, and idarubicin (FLAG-IDA) as cytoreductive chemotherapy followed by busulfan and fludarabine (Flu-BU) conditioning regimen and transfusion of mobilized peripheral stem cells from human leukocyte antigen-matched sibling or unrelated donor. The primary endpoint of the study was 2-year leukemia-free survival (LFS) and secondary endpoints included complete-remission rate, 2-year overall survival (OS), nonrelapse mortality (NRM), and relapse rate. A total of 16 patients were enrolled with median age of 36 (16-60), which included 9 primary induction failure, 2 early relapse, and 5 with relapse/refractory disease. The median cycles of previous chemotherapy were 4 (3-10) with a median of 55% (1%-90%) blasts in bone marrow. Six patients received transplantation from matched sibling and 10 from matched unrelated donors. After transplantation, 15 patients achieved bone marrow remission (11 complete remissions [CRs] and 4 bone marrow remissions without platelet recovery) at day +28. A total of 8 patients remained alive in CR with median LFS of 29.5 months (9.5-40.5 months). Four patients relapsed and 3 of them died of disease and another 4 patients died because of transplantation-related toxicity. The 2-year NRM and relapse rates were 25.0% ± 10.8% and 33.4% ± 13.8%, respectively with 2-year OS at 53.5% ± 13.1% and LFS at 50.0% ± 12.5%. Based on the Simon 2-stage design, 5 out of first eligible 14 patients remained leukemia-free for more than 2 years after allogeneic hematopoietic stem cell transplantation; thus, the null hypothesis of the study will be rejected and the study protocol is accepted as being warranted for further study. Based on the above data, our phase II study demonstrated that the sequential FLAG-IDA cytoreduction chemotherapy followed by Flu-BU conditioning regimen given at the hematological nadir was feasible and has sufficient activity to warrant further investigation prospectively with a larger patient sample (clinicaltrials.gov identifier: NCT01496547).

Allogeneic stem cell transplantation for refractory acute myeloid leukemia: a single center analysis of long-term outcome

For patients with refractory acute myeloid leukemia (AML), allogeneic stem cell transplantation (alloSCT) represents the only curative approach. We here analyzed the long-term outcome of 131 consecutive patients with active AML, which was either primary refractory or unresponsive to salvage chemotherapy, transplanted at our center between 1997 and 2013. After a median follow-up of 48 months for the surviving patients, disease-free survival (DFS) at 5 yr post alloSCT was 26% (94% CI: 17-35). Relapses, most of which occurred within the first 2 yr from transplant, were the predominant cause of treatment failure affecting 48% (95%CI: 40-58) of patients, whereas non-relapse mortality was 26% (95%CI: 20-36) at 5 yr and thereafter. A marrow blast count ≥20% before alloSCT was an independent prognosticator associated with an inferior DFS (HR: 1.58, P = 0.027), whereas the development of chronic graft-versus-host disease (cGvHD) predicted an improved DFS (HR 0.21, P < 0.001) and a decreased relapse incidence (HR: 0.18, P = 0.026), respectively. These results indicate that alloSCT represents a curative treatment option in a substantial proportion of patients with refractory AML. A pretransplant blast count <20% before alloSCT and the development of cGvHD are the most important predictors of long-term disease control.

Fate of patients with newly diagnosed acute myeloid leukemia who fail primary induction therapy

The aim of this study was to describe the fate of patients with newly diagnosed acute myeloid leukemia (AML) who did not achieve an initial remission while being treated on a contemporary cooperative group trial. We analyzed the outcome of patients entered into S0106, a recently reported cooperative group trial for patients with newly diagnosed AML. A total of 589 eligible patients was treated, of whom 150 (25%) did not achieve a remission while on study and were available for further analysis. The 4-year survival rate for the entire cohort of 150 patients was 23%. Among the 64 patients who received an allogeneic hematopoietic cell transplant, the 4-year survival rate was 48% compared with 4% for the 86 patients who did not undergo transplantation. Among those transplanted, we could not detect a difference in outcome according to remission status, donor source, type of preparative regimen, or cytogenetic risk category. More than 20% of patients with newly diagnosed AML who fail induction therapy can still be cured, particularly if they are able to receive an allogeneic hematopoietic cell transplant. These results suggest that early HLA typing and donor identification are important components of the initial therapy of AML.

[Current indications of allogeneic stem cell transplant in adults with acute myeloid leukemia]

Allogeneic stem cell transplantation (SCT) is an increasingly important therapeutic option for the treatment of adult patients with acute myeloid leukemia. Here we review the current indications of SCT in this disease. While patients with favorable cytogenetics should receive consolidation chemotherapy, patients with unfavorable karyotype are prime candidates for SCT or new approaches to SCT (which should be done in first complete remission). Patients with intermediate prognoses should also receive SCT in first complete remission. In the absence of a suitable matched related donor, most patients will be able to find an alternative donor to proceed to a potentially curative allogeneic transplantation. The use of reduced-intensity conditioning regimens before SCT has allowed patients in the sixth or seventh decades of life to be routinely transplanted. Despite major differences among transplant centers in the intensity and composition of the conditioning regimen and immunosuppression, choice of graft source, postgraft immune-modulation, and supportive care, there has been a dramatic improvement in terms of tolerance. Although it is presumed to be a curative strategy, major complications of SCT remain graft-versus-host disease, delayed immune recovery, multiple comorbidities, and relapse after transplant.

Allogeneic hematopoietic cell transplant for acute myeloid leukemia: Current state in 2013 and future directions

Acute myeloid leukemia (AML) represents a heterogeneous group of high-grade myeloid neoplasms of the elderly with variable outcomes. Though remission-induction is an important first step in the management of AML, additional treatment strategies are essential to ensure long-term disease-free survival. Recent pivotal advances in understanding the genetics and molecular biology of AML have allowed for a risk-adapted approach in its management based on relapse-risk. Allogeneic hematopoietic cell transplantation (allo-HCT) represents an effective therapeutic strategy in AML providing the possibility of cure with potent graft-versus-leukemia reactions, with a demonstrable survival advantage in younger patients with intermediate- or poor-risk cytogenetics. Herein we review the published data regarding the role of allo-HCT in adults with AML. We searched MEDLINE/PubMed and EMBASE/Ovid. In addition, we searched reference lists of relevant articles, conference proceedings and ongoing trial databases. We discuss the role of allo-HCT in AML patients stratified by cytogenetic- and molecular-risk in first complete remission, as well as allo-HCT as an option in relapsed/refractory AML. Besides the conventional sibling and unrelated donor allografts, we review the available data and recent advances for alternative donor sources such as haploidentical grafts and umbilical cord blood. We also discuss conditioning regimens, including reduced intensity conditioning which has broadened the applicability of allo-HCT. Finally we explore recent advances and future possibilities and directions of allo-HCT in AML. Practical therapeutic recommendations have been made where possible based on available data and expert opinion.

Factors predictive of relapse of acute leukemia in children after allogeneic hematopoietic cell transplantation

The presence of minimal residual disease (MRD) before transplantation is the most important prognostic risk factor predictive of post-transplantation relapse in hematologic malignancies. However, MRD alone does not adequately predict relapse in all patients. To improve upon the ability to identify patients likely to relapse, we evaluated risk factors, in addition to MRD, that may be associated with development of post-transplantation relapse. In this single institution, retrospective cohort study of children with acute leukemia or myelodysplastic syndrome who had undergone a first allogeneic transplantation and had pretransplantation MRD evaluation, 40 of 93 patients (43%) experienced relapse. Univariate analysis demonstrated that African American race, high initial white blood cell count, central nervous system (CNS) disease at diagnosis, short first complete remission, nonmyeloablative (NMA) conditioning, lack of remission, and MRD before transplantation were associated with worse relapse-free survival (RFS). In a Cox multivariable analysis, CNS disease (P = .009), lack of remission (P = .01), and NMA conditioning (P = .04) were independently associated with inferior RFS. Among those in a morphologic complete remission who underwent a myeloablative transplantation, having both CNS disease at diagnosis (specifically in acute lymphoblastic leukemia) and MRD positivity was an independent risk factor predictive of relapse, which has not been previously reported. Results from our study support the existence of risk factors complimentary to pretransplantation MRD. Validation in a larger independent homogenous cohort is needed to develop a prognostic tool for clinical use to predict post-transplantation relapse.

Indications for allogeneic hematopoietic cell transplantation for acute myeloid leukemia in the genomic era

Few choices in medical oncology are as stark as the decision of whether or not to proceed with allogeneic hematopoietic cell transplantation (HCT) in the treatment of acute myeloid leukemia (AML). Recent advances provide more information to inform the decision, including molecular studies of leukemia that predict tumor responsiveness, assays of minimal residual disease that measure early treatment outcome, and comorbidity indices that predict nonrelapse mortality. Although large prospective studies incorporating all of these factors are lacking, literature reviews and consensus statements exist that can help the clinician in this difficult choice. Allogeneic HCT should be considered for all patients younger than age 65, with an available donor, an acceptable comorbidity index, and whose had initial induction therapy has failed. Similarly, allogeneic HCT is appropriate therapy for all patients with AML in second remission younger than age 75, with an appropriate donor, and a comorbidity index of 5 or less. For patients younger than age 60 with AML in first complete remission (CR), there is little evidence that HCT benefits those with favorable-risk disease who achieve CR with one cycle of induction and have no evidence of minimal residual disease. Allogeneic HCT is indicated for essentially all other categories of patients. For those age 60 and older, few prospective studies are available on which to base recommendations, but, as in younger patients, the benefit of allogeneic HCT is questionable for patients with favorable-risk AML. For patients with higher-risk disease, allogeneic HCT is a reasonable option with the caution that the risk of HCT increases dramatically in those with a comorbidity index of 3 or higher.

Providing personalized prognostic information for adult leukemia survivors

Prediction of subsequent leukemia-free survival (LFS) and chronic graft-versus-host disease (GVHD) in adults with acute leukemia who survived at least 1 year after allogeneic hematopoietic cell transplantation is difficult. We analyzed 3339 patients with acute myeloid leukemia and 1434 patients with acute lymphoblastic leukemia who received myeloablative conditioning and related or unrelated stem cells from 1990 to 2005. Most clinical factors predictive of LFS in 1-year survivors were no longer significant after 2 or more years. For acute myeloid leukemia, only disease status (beyond first complete remission) remained a significant adverse risk factor for LFS 2 or more years after transplantation. For lymphoblastic leukemia, only extensive chronic GVHD remained a significant adverse predictor of LFS in the second and subsequent years. For patients surviving for 1 year without disease relapse or extensive chronic GVHD, the risk of developing extensive chronic GVHD in the next year was 4% if no risk factors were present and higher if noncyclosporine-based GVHD prophylaxis, an HLA-mismatched donor, or peripheral blood stem cells were used. Estimates for subsequent LFS and extensive chronic GVHD can be derived for individual patients or populations using an online calculator (http://www.cibmtr.org/LeukemiaCalculators). This prognostic information is more relevant for survivors than estimates provided before transplantation.

Cotransplantation of haploidentical hematopoietic and umbilical cord mesenchymal stem cells with a myeloablative regimen for refractory/relapsed hematologic malignancy

Human leukocyte antigen haploidentical hematopoietic stem-cell transplantation (haplo-HSCT) is associated with an increased risk of graft failure and severe graft-versus-host disease (GVHD). Mesenchymal stromal cells (MSCs) have been shown to support in vivo normal hematopoiesis and to display potent immunesuppressive effects. We cotransplanted the culture-expanded third-party donor-derived umbilical cord MSCs (UC-MSCs) in 50 people with refractory/relapsed hematologic malignancy undergoing haplo-HSCT with myeloablative conditioning. We observed that all patients given MSCs showed sustained hematopoietic engraftment without any adverse UC-MSC infusion-related reaction. The median times to neutrophil >0.50 × 10(9)/L and platelet >20 × 10(9)/L engraftment were 12.0 and 15.0 days, respectively. We did not observe an increase in severe acute GVHD (aGVHD) and extensive chronic GVHD (cGVHD), too. Grade II-IV aGVHD was observed in 12 of 50 (24.0 %) patients. cGVHD was observed in 17 of 45 (37.7 %) patients and was extensive in 3 patients. Additionally, only five patients (10.0 %) experienced relapse at a median time to progression of 192 days. The probability that patients would attain progression-free survival at 2 years was 66.0 %. The results indicate that this new strategy is effective in improving donor engraftment and reducing severe GVHD, which will provide a feasible option for the therapy of high-risk hematologic malignancy.

Outcome of treatment after first relapse in younger adults with acute myeloid leukemia initially treated by the ALFA-9802 trial

Forty-seven percent of adults with acute myeloid leukemia (AML) who entered the ALFA-9802 trial and achieved a first complete remission (CR) experienced a first relapse. We examined the outcome of these 190 adult patients. Eighty-four patients (44%) achieved a second CR. The median overall survival (OS) after relapse was 8.9 months with a 2-year OS at 25%. Factors predicting a better outcome after relapse were stem cell transplant (SCT) performed in second CR and a first CR duration >1 year. Risk groups defined at the time of diagnosis and treatment received in first CR also influenced the outcome after relapse. The best results were obtained in patients with core binding factor (CBF)-AML, while patients initially defined as favorable intermediate risk showed a similar outcome after relapse than those initially entering the poor risk group. We conclude that most adult patients with recurring AML could not be rescued using current available therapies, although allogeneic SCT remains the best therapeutic option at this stage of the disease.