Hematopoietic stem cell transplantation for core binding factor acute myeloid leukemia: t(8;21) and inv(16) represent different clinical outcomes

Allogeneic hematopoietic cell transplantation for acute myeloid leukemia with hyperdiploid complex karyotype

Allogeneic hematopoietic cell transplantation (allo-HCT) remains the best consolidation strategy for acute myeloid leukemia (AML) with complex karyotype (CK). However, CK is a heterogenous and highly diverse entity. Numerical abnormalities have been associated with a controversial prognosis and AML with only multiple numerical abnormalities known as pure hyperdiploid karyotype (HDK) may have a distinct prognosis after allo-HCT compared to non-pure HDK CK AML. A total of 236 patients were identified within the EBMT registry as having HDK comprising 95 pure (pHDK) and 141 with other cytogenetic abnormalities (HDK+). The 2-year probability of leukemia-free survival (LFS) was 50% for pHDK and 31% for HDK+ (p = 0.003). The 2-year probability of overall survival (OS) was 57% for pHDK and 36% for HDK+ (p = 0.007). The 2-year cumulative incidence of relapse (RI) was 22% for pHDK and 44% for HDK+ (p = 0.001). The 2-year probability of graft-versus-host disease (GvHD)-free and relapse-free survival (GRFS) was 36% for pHDK and 21% for HDK+ (p = 0.01). On multivariate analysis, pHDK remained associated with significantly better LFS, OS and GRFS and lower RI (all p-values <0.004). pHDK AML constitutes probably a distinct cytogenetic entity from HDK+ or other non-hyperdiploid CK AML with better outcomes after allo-HCT.

Impact of measurable residual disease in combination with CD19 on postremission therapy choices for adult t(8;21) acute myeloid leukemia in first complete remission

BACKGROUND

The post-remission therapy (PRT) choices for adult t(8;21) acute myeloid leukemia (AML) in first complete remission (CR1) need to be further explored.

AIMS

We aimed to investigate the impact of measurable residual disease (MRD) combined with CD19 on PRT choices for adult t(8;21) AML in CR1.

METHODS

A total of 150 t(8;21) AML patients were enrolled, including 67 underwent chemotherapy (CMT) and 83 allogeneic hematopoietic stem cell transplantation (allo-SCT) as PRT in CR1. Subgroup analyses were performed according to MRD level after three cycles of chemotherapy combined with CD19 expression.

RESULTS

Multivariate analysis indicated MRDhigh after three courses of treatment (HR, 0.14 [95% CI, 0.03-0.66]; p = 0.013) and CD19 negativity (HR, 0.14 [95% CI, 0.02-0.96]; p = 0.045) were risk factors for relapse, while allo-SCT was protective factor for relapse (HR, 0.34 [95% CI, 0.15-0.75]; p = 0.008). Grouped by MRD after three courses of chemotherapy, allo-SCT had lower CIR (p < 0.001) and better OS (p = 0.003) than CMT for MRDhigh patients, CMT showed a higher CIR (35.99% vs. 15.34%, p = 0.100) but comparable OS (p = 0.588) than allo-SCT for MRDlow patients. Grouped by CD19 expression, allo-SCT demonstrated lower CIR (p < 0.001) and better OS (p = 0.002) than CMT for CD19- patients. CMT had a higher CIR (41.37% vs. 10.48%, p = 0.007) but comparable OS (p = 0.147) than allo-SCT for CD19+ patients. Grouped by MRD combined with CD19, MRDhigh /CD19+ subsets were identified out of CD19+ patients benefiting from allo-SCT with lower CIR (p = 0.002) and superior OS (p = 0.020) than CMT. CMT preserved comparable CIR (p = 0.939) and OS (p = 0.658) with allo-SCT for MRDlow /CD19+ patients. MRDlow /CD19- subsets were also identified from MRDlow patients requiring allo-SCT with lower CIR (p < 0.001) and superior OS (p = 0.008) than CMT. Allo-SCT maintained lower CIR (p < 0.001) and superior OS (p = 0.008) than CMT for MRDhigh /CD19- patients.

CONCLUSIONS

MRD combined with CD19 might optimize PRT choices for adult t(8;21) AML patients in CR1.

Proteogenomic analysis reveals cytoplasmic sequestration of RUNX1 by the acute myeloid leukemia-initiating CBFB::MYH11 oncofusion protein

Several canonical translocations produce oncofusion genes that can initiate acute myeloid leukemia (AML). Although each translocation is associated with unique features, the mechanisms responsible remain unclear. While proteins interacting with each oncofusion are known to be relevant for how they act, these interactions have not yet been systematically defined. To address this issue in an unbiased fashion, we fused a promiscuous biotin ligase (TurboID) in-frame with 3 favorable-risk AML oncofusion cDNAs (PML::RARA, RUNX1::RUNX1T1, and CBFB::MYH11) and identified their interacting proteins in primary murine hematopoietic cells. The PML::RARA- and RUNX1::RUNX1T1-TurboID fusion proteins labeled common and unique nuclear repressor complexes, implying their nuclear localization. However, CBFB::MYH11-TurboID-interacting proteins were largely cytoplasmic, probably because of an interaction of the MYH11 domain with several cytoplasmic myosin-related proteins. Using a variety of methods, we showed that the CBFB domain of CBFB::MYH11 sequesters RUNX1 in cytoplasmic aggregates; these findings were confirmed in primary human AML cells. Paradoxically, CBFB::MYH11 expression was associated with increased RUNX1/2 expression, suggesting the presence of a sensor for reduced functional RUNX1 protein, and a feedback loop that may attempt to compensate by increasing RUNX1/2 transcription. These findings may have broad implications for AML pathogenesis.

The core concepts of core binding factor acute myeloid leukemia: Current considerations for prognosis and treatment

Core binding factor acute myeloid leukemia (CBF AML), defined by t(8;21) or inv(16), is a subset of favorable risk AML. Despite its association with a high complete remission rate after induction and relatively good prognosis overall compared with other subtypes of AML, relapse risk after induction chemotherapy remains high. Optimizing treatment planning to promote recurrence free survival and increase the likelihood of survival after relapse is imperative to improving outcomes. Recent areas of research have included evaluation of the role of gemtuzumab in induction and consolidation, the relative benefit of increased cycles of high dose cytarabine in consolidation, the utility of hypomethylating agents and kinase inhibitors, and the most appropriate timing of stem cell transplant. Surveillance with measurable residual disease testing is increasingly being utilized for monitoring disease in remission, and ongoing investigation seeks to determine how to use this tool for early identification of patients who would benefit from proceeding to transplant. In this review, we outline the current therapeutic approach from diagnosis to relapse while highlighting the active areas of investigation in each stage of treatment.

Comparison of outcomes for patients with acute myeloid leukemia undergoing haploidentical stem cell transplantation in first and second complete remission

There was no consensus on whether prognostic advantages existed when transplant conducted at first complete remission (CR1) stage than at second complete remission (CR2) stage for patients with AML who received haploidentical hematological stem cell transplantation (haplo-HSCT). In 768 consecutive AML patients who received haplo-HSCT from January 2014 to December 2017, a 1:2 ratio matched-pair analysis was performed, 69 patients who in CR2 group and 138 CR1 patients were enrolled. Hematopoietic recovery, graft versus host disease (GVHD), relapse, transplant related mortality (TRM), disease-free survival (DFS) and overall survival (OS) were compared in two groups, and further evaluated in low-, intermediate-, and high-risk subgroups. The cumulative incidences of 30-day myeloid recovery and 90-day platelet recovery were comparable in CR1 and CR2 groups. The cumulative incidences of grade II-IV and grade III-IV aGVHD were not significantly different. The cumulative incidences of relapse at 3-year and 5-year in these two groups were 12.4% versus 11.6% (P = 0.880) and 12.4% versus 17.5% (P = 0.322). The cumulative incidences of TRM at 3-year and 5-year were both 10.9% versus 23.2% (P = 0.019). The probability of DFS at 3-year and 5-year were 76.7% versus 65.2% (P = 0.029) and 76.7% versus 59.3% (P = 0.009). The probability of OS at 3-year and 5-year were 81.8% versus 68.1% (P = 0.026) and 76.7% versus 59.3% (P = 0.026). In the intermediate-risk group, TRM was lower in CR1 group, DFS and OS of CR1 group were superior to CR2 group. In conclusion, haplo-HSCT at CR1 stage was of better prognosis for intermediate-risk AML patients than at CR2 stage.

Characteristics and outcome of patients with core-binding factor acute myeloid leukemia and FLT3-ITD: results from an international collaborative study

The aim of this study was to evaluate the prognostic impact of FLT3-ITD in core-binding factor acute myeloid leukemia (CBFAML) in an international, multicenter survey of 97 patients of whom 52% had t(8;21)(q22;q22) and 48% had inv(16)(p13q22)/t(16;16)(p13;q22). The median age of the patients was 53 years (range, 19-81). Complete remission after anthracycline-based induction (n=86) and non-intensive therapy (n=11) was achieved in 97% and 36% of the patients, respectively. The median follow-up was 4.43 years (95% confidence interval [95% CI]: 3.35-7.39 years). The median survival after intensive and non-intensive treatment was not reached and 0.96 years, respectively. Among intensively treated patients, inv(16) with trisomy 22 (n=11) was associated with a favorable 4-year relapse-free survival rate of 80% (95% CI: 59-100%) as compared to 38% (95% CI: 27-54%; P=0.02) in all other patients with CBFAML/ FLT3-ITD (n=75). Overall, 24 patients underwent allogeneic hematopoietic cell transplantation (HCT), 12 in first complete remission and 12 after relapse. Allogeneic HCT in first complete remission was not beneficial (P=0.60); however, allogeneic HCT seemed to improve median survival in relapsed patients compared to that of patients treated with chemotherapy (not reached vs. 0.6 years, respectively; P=0.002). Excluding patients with inv(16) with trisomy 22, our data indicate that compathe outcome of CBF-AML patients with FLT3-ITD may be inferior to that of patients without FLT3-ITD (based on previously published data), suggesting that prognostically CBF-AML patients with FLT3-ITD should not be classified as favorable-risk. FLT3-inhibitors may improve the outcome of these patients.

How to Improve Prognostication in Acute Myeloid Leukemia with CBFB-MYH11 Fusion Transcript: Focus on the Role of Molecular Measurable Residual Disease (MRD) Monitoring

Acute myeloid leukemia (AML) carrying inv(16)/t(16;16), resulting in fusion transcript CBFB-MYH11, belongs to the favorable-risk category. However, even if most patients obtain morphological complete remission after induction, approximately 30% of cases eventually relapse. While well-established clinical features and concomitant cytogenetic/molecular lesions have been recognized to be relevant to predict prognosis at disease onset, the independent prognostic impact of measurable residual disease (MRD) monitoring by quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR), mainly in predicting relapse, actually supersedes other prognostic factors. Although the ELN Working Party recently indicated that patients affected with CBFB-MYH11 AML should have MRD assessment at informative clinical timepoints, at least after two cycles of intensive chemotherapy and after the end of treatment, several controversies could be raised, especially on the frequency of subsequent serial monitoring, the most significant MRD thresholds (most commonly 0.1%) and on the best source to be analyzed, namely, bone marrow or peripheral blood samples. Moreover, persisting low-level MRD positivity at the end of treatment is relatively common and not predictive of relapse, provided that transcript levels remain stably below specific thresholds. Rising MRD levels suggestive of molecular relapse/progression should thus be confirmed in subsequent samples. Further prospective studies would be required to optimize post-remission monitoring and to define effective MRD-based therapeutic strategies.

Prognostic value of measurable residual disease at allogeneic transplantation for adults with core binding factor acute myeloid leukemia in complete remission

Pretransplant measurable residual disease (MRD) has been shown to be associated with relapse incidence following allogeneic hematopoietic cell transplantation (HCT) for acute myeloid leukemia (AML). However, it remains less clear whether pretransplant MRD status affects transplant outcomes in core binding factor AML (CBF-AML). We retrospectively evaluated the effect of pretransplant MRD, which was measured by a polymerase chain reaction of RUNX1-RUNX1T1 or CBFB-MYH11 fusion transcripts, on transplant outcomes for a cohort of 959 adult patients with t(8;21) or inv(16) AML treated by allogeneic HCT during complete remission (CR), between 2000 and 2018. Multivariate analysis showed the absence of pretransplant MRD was significantly associated with lower relapse (hazard ratio [HR], 0.46; P < 0.001), treatment failure (HR, 0.66; P = 0.004), and overall mortality (HR, 0.72; P = 0.037) among patients with t(8;21). However, pretransplant MRD negativity was not associated with relapse (HR, 0.73; P = 0.420), treatment failure (HR, 0.64; P = 0.063), or overall mortality (HR, 0.69; P = 0.149) among patients with inv(16). In subgroup analysis, pretransplant MRD status significantly affected relapse and LFS only in patients with t(8;21) undergoing allogeneic HCT during CR2. In conclusion, our data demonstrate the different prognostic values of pretransplant MRD for CBF-AML, highlighting the need to develop effective therapeutic strategies for such MRD-positive patients.

Prognostic values of D816V KIT mutation and peri-transplant CBFB-MYH11 MRD monitoring on acute myeloid leukemia with CBFB-MYH11

Given the controversies in the prognostic value of KIT mutations and optimal thresholds and time points of MRD monitoring for AML with CBFB-MYH11, we retrospectively evaluated 88 patients who underwent allogeneic hematopoietic stem cell transplantation (Allo-HSCT, n = 60) or autologous HSCT (Auto-HSCT, n = 28). The D816V KIT mutation was significantly associated with post-transplant relapse, contrasting with other types of mutations in KIT. Pre- and post-transplant (3 months after transplant) CBFB-MYH11 MRD assessments were useful in predicting post-transplant relapse and poor survival. The optimal threshold was determined as a 2 log reduction at both time points. In multivariate analysis, the D816V KIT mutation and CBFB-MYH11 MRD assessments were independently associated with post-transplant relapse and survival. Stratification by D816V KIT and pre-transplant CBFB-MYH11 MRD status further distinguished the risk of relapse and survival. Auto-HSCT was superior to Allo-HSCT in MRD negative patients without D816V KIT, while Allo-HSCT trended to be superior to Auto-HSCT in patients with MRD positivity or the D816V KIT mutation. In conclusion, this study demonstrated the differentiated prognostic value of the D816V KIT mutation in AML with CBFB-MYH11 and clarified optimal time points and thresholds for CBFB-MYH11 MRD monitoring in the setting of HSCT.

Autologous hematopoietic cell transplantation following high-dose cytarabine consolidation for core-binding factor-acute myeloid leukemia in first complete remission: a phase 2 prospective trial

Core-binding factor (CBF)-acute myeloid leukemia (AML) generally have a favorable prognosis. However, approximately 50% of patients experience disease relapse during or after post-remission therapy. Retrospective studies on autologous hematopoietic cell transplantation (AHCT) have shown improved survival with decreased relapse rate in CBF-AML. In this prospective study, we evaluate the outcomes of AHCT following high-dose cytarabine (HiDAC) consolidation in patients with CBF-AML in first complete remission (CR). Adult patients with CBF-AML achieving first CR after induction chemotherapy were eligible for the study. High-dose chemotherapy before AHCT included intravenous busulfan (3.2 mg/kg/day, days - 7 to - 5) and etoposide (400 mg/m²/day, days - 3 to - 2). Twenty-nine patients, 17 with t(8;21) and 12 with inv(16), underwent AHCT following 2 or 3 courses of HiDAC consolidation. The estimated 5-year overall and disease-free survival rates were between 89.0% and 82.5%, respectively. The cumulative incidences of relapse and non-relapse mortality were between 17.5% and 0%, respectively. Presence of measurable residual disease (MRD) before AHCT and KIT mutation were significantly associated with relapse after transplantation. In conclusion, the post-remission strategy of AHCT following HiDAC consolidation in CBF-AML was feasible and efficacious. Assays for MRD and KIT mutation may guide selection of patients who will benefit from AHCT in CBF-AML in first CR.

Prognostic Impacts of D816V KIT Mutation and Peri-Transplant RUNX1-RUNX1T1 MRD Monitoring on Acute Myeloid Leukemia with RUNX1-RUNX1T1

Simple Summary

Acute myeloid leukemia (AML) with RUNX1-RUNX1T1 is a heterogeneous disease entailing different prognoses. Patients with high-risk features can benefit from allogeneic hematopoietic stem cell transplantation (HSCT) or autologous HSCT. However, insufficient data about major risk factors, such as KIT mutations and measurable residual disease (MRD) status for relapse, make it difficult to clarify the benefit of each transplant strategy. Moreover, limited data are available to elucidate the exact prognostic impacts of different types of KIT mutations and optimal thresholds or time points for RUNX1–RUNX1T1 MRD assessment, particularly in the setting of HSCT. Given the lack of prospective study, the current retrospective study, including a large cohort of high-risk AML patients with RUNX1–RUNX1T1, firstly demonstrated the differentiated prognostic impact of D816V KIT mutation among various KIT mutations and clarified optimal time points and thresholds for RUNX1–RUNX1T1 MRD monitoring in the setting of HSCT.

Abstract

The prognostic significance of KIT mutations and optimal thresholds and time points of measurable residual disease (MRD) monitoring for acute myeloid leukemia (AML) with RUNX1-RUNX1T1 remain controversial in the setting of hematopoietic stem cell transplantation (HSCT). We retrospectively evaluated 166 high-risk patients who underwent allogeneic (Allo-HSCT, n = 112) or autologous HSCT (Auto-HSCT, n = 54). D816V KIT mutation, a subtype of exon 17 mutations, was significantly associated with post-transplant relapse and poor survival, while other types of mutations in exons 17 and 8 were not associated with post-transplant relapse. Pre- and post-transplant RUNX1–RUNX1T1 MRD assessments were useful for predicting post-transplant relapse and poor survival with a higher sensitivity at later time points. Survival analysis for each stratified group by D816V KIT mutation and pre-transplant RUNX1–RUNX1T1 MRD status demonstrated that Auto-HSCT was superior to Allo-HSCT in MRD-negative patients without D816V KIT mutation, while Allo-HSCT was superior to Auto-HSCT in MRD-negative patients with D816V KIT mutation. Very poor outcomes of pre-transplant MRD-positive patients with D816V KIT mutation suggested that this group should be treated in clinical trials. Risk stratification by both D816V KIT mutation and RUNX1–RUNX1T1 MRD status will provide a platform for decision-making or risk-adapted therapeutic approaches.

Hematopoietic Cell Transplantation in the Treatment of Newly Diagnosed Adult Acute Myeloid Leukemia: An Evidence-Based Review from the American Society of Transplantation and Cellular Therapy

The role of hematopoietic cell transplantation (HCT) in the management of newly diagnosed adult acute myeloid leukemia (AML) is reviewed and critically evaluated in this evidence-based review. An AML expert panel, consisting of both transplant and nontransplant experts, was invited to develop clinically relevant frequently asked questions covering disease- and HCT-related topics. A systematic literature review was conducted to generate core recommendations that were graded based on the quality and strength of underlying evidence based on the standardized criteria established by the American Society of Transplantation and Cellular Therapy Steering Committee for evidence-based reviews. Allogeneic HCT offers a survival benefit in patients with intermediate- and high-risk AML and is currently a part of standard clinical care. We recommend the preferential use of myeloablative conditioning in eligible patients. A haploidentical related donor marrow graft is preferred over a cord blood unit in the absence of a fully HLA-matched donor. The evolving role of allogeneic HCT in the context of measurable residual disease monitoring and recent therapeutic advances in AML with regards to maintenance therapy after HCT are also discussed.

Allogeneic Hematopoietic Stem Cell Transplantation Improved Survival for Adult Core Binding Factor Acute Myelogenous Leukemia Patients with Intermediate- and Adverse-Risk Genetics in the 2017 European LeukemiaNet

The use of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for consolidation therapy in patients with core binding factor (CBF) acute myelogenous leukemia (AML) with intermediate- and adverse-risk genetics remains controversial. We retrospectively analyzed the clinical outcomes of 286 CBF-AML patients with intermediate- and adverse-risk genetics in first complete remission following consolidation with chemotherapy (n = 122), auto-HSCT (n = 27), or allo-HSCT (n = 137) between January 2009 and December 2018 at our center. Patients with allo-HSCT showed superior 5-year overall survival (OS; 74% versus 38% or 49%; P < .001) and progression-free survival (PFS; 74% versus 26% or 49%; P < .001) and lower cumulative incidence of relapse (CIR; 9% versus 69% or 31%; P < .001) compared with chemotherapy alone or auto-HSCT. In the allo-HSCT group, minimal residual disease (MRD) at the second and third months after allo-HSCT could predict relapse in t(8;21) patients (2 months: P_CIR = .002; 3 months: P_CIR < .001) but not in inv(16) patients. Moreover, positive MRD after 2 courses of consolidation chemotherapy before allo-HSCT was an independent risk factor for survival in CBF-AML patients with intermediate- and adverse-risk genetics, whereas haploidentical donor (haplo-) HSCT could overcome the adverse prognosis (5-year OS, 87%; 5-year PFS, 81%; 5-year CIR, 7%). Allo-HSCT could be the optimal first-line consolidation therapy for patients with intermediate- and adverse-risk genetics, and haplo-HSCT could improve survival for patients with positive MRD after 2 courses of consolidation chemotherapy.

Allogeneic stem cell transplantation in second complete remission for core binding factor acute myeloid leukemia: a study from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Core binding factor acute myeloid leukemia (AML) comprises two subtypes with distinct cytogenetic abnormalities of either t(8;21)(q22;q22) or inv(16)(p13q22)/t(16;16)(p13;q22). Since long-term response to chemotherapy in these leukemias is relatively good, allogeneic hematopoietic stem cell transplantation is considered in patients who relapse and achieve second complete remission. To evaluate the outcomes of allogeneic transplantation in this indication, we studied 631 patients reported to the European Society for Blood and Marrow Transplantation Registry between the years 2000 and 2014. Leukemia-free survival probabilities at two and five years were 59.1% and 54.1%, while overall survival probabilities were 65% and 58.2%, respectively. The incidence of relapse and risk of non-relapse mortality at the same time points were 19.8% and 22.5% for relapse and 20.9% and 23.3% for non-relapse mortality, respectively. The most important adverse factors influencing leukemia-free and overall survival were: leukemia with t(8;21), presence of three or more additional chromosomal abnormalities, and Karnofsky performance score <80. Relapse risk was increased in t(8;21) leukemia and associated with additional cytogenetic abnormalities as well as reduced intensity conditioning. Measurable residual disease in molecular evaluation before transplantation was associated with increased risk of relapse and inferior leukemia-free survival.

Autologous Hematopoietic Stem Cell Transplantation in Acute Myelogenous Leukemia

The clinical outcomes of autologous hematopoietic stem cell transplantation (ASCT) in acute myelogenous leukemia (AML) have improved over time. Indeed, numerous studies have demonstrated that ASCT is associated with a lower relapse rate and acceptable nonrelapse mortality compared with chemotherapy alone in patients with AML. In addition, ASCT is also associated with comparable overall survival outcomes to those of allogeneic hematopoietic stem cell transplantation in some patients with AML. To date, age, cytogenetic and molecular risk stratification, and minimal residual disease (MRD) status have been shown to be closely related to clinical outcomes following ASCT. ASCT is recommended for patients with favorable-risk and intermediate-risk AML in first complete remission and patients with acute promyelocytic leukemia in second complete remission for whom a matched sibling donor is not available. MRD status pre-ASCT is the most important factor to consider when determining whether a patient is eligible for ASCT and can effectively predict clinical outcomes after ASCT. Advanced age is not an absolute contradiction for ASCT. In this review, we describe the literature and clinical trials evaluating the outcomes of ASCT in patients with AML and discuss the indications for ASCT therapy. Because the greatest concern in ASCT recipients is early relapse, important factors that should be monitored before ASCT and future perspectives in this area are also presented.

Different prognostic effects of core-binding factor positive AML with Korean AML registry data

Core-binding factor acute myeloid leukemia (CBF-AML) data in Asian countries has been rarely reported. We analyzed 392 patients with CBF-AML [281 with t(8;21), 111 with inv.(16)/t(16;16)] among data from 3041 patients with AML from the Korean AML Registry. Interestingly, del(9q) was less frequently detected in Korean than in German patients with t(8;21) (7.5% vs. 17%), and del(7q) was more frequently detected in Korean patients with inv(16). Overall survival (OS) was similar between patients in the first complete remission (CR) who received allogeneic (alloSCT) and autologous stem cell transplantation (ASCT) for CBF-AML. OS of t(8;21) patients was poor when undergoing alloSCT in second/third CR, while OS of inv(16) patients in second/third CR was similar to that in first CR. Patients with > 3-log reduction of RUNX1/RUNX1T1 qPCR had improved 3-year event-free survival (EFS) than those without (73.2% vs. 50.3%). Patients with t(8;21) AML with D816 mutation of the c-Kit gene showed inferior EFS and OS. These poor outcomes might be overcome by alloSCT. Multivariate analysis for OS in patients with t(8;21) revealed older age, > 1 course of induction chemotherapy to achieve CR, loss of sex chromosome, del(7q), and second/third CR or not in CR before SCT as independent prognostic variables. Especially, del(7q) is the most powerful prediction factor of poor outcomes, especially in patients with t(8;21) (hazard ratio, 27.23; P < 0.001). Further study is needed to clarify the clinical effect of cytogenetics and gene mutation in patients with CBF-AML, between Asian and Western countries.

Hematopoietic stem cell transplantation for adult patients with isolated NPM1 mutated acute myeloid leukemia in first remission

Acute myeloid leukemia (AML) in first remission (CR1) with isolated NPM1 mutation (iNPM1m) is considered a good prognosis genotype, although up to one-third relapse. To evaluate the best transplant strategy, we retrospectively compared autologous stem cell transplantation (auto-SCT), related (MSD), and fully matched unrelated (MUD) allogeneic stem cell transplantation (allo-SCT). We identified 256 adult patients including 125 auto-SCT, 72 MSD, and 59 MUD. The 2-year leukemia-free survival (LFS) was 62% in auto-SCT, 69% in MUD, and 81% in MSD (P = .02 for MSD vs others). The 2-year overall survival (OS) was not different among auto-SCT, MUD, and MSD, reaching 83% (P = .88). The 2-year non-relapse mortality (NRM) was 2.5% in auto-SCT and 7.5% in allo-SCT (P = .04). The 2-year cumulative incidence of relapse (RI) was higher after auto-SCT (30%) than after MUD (22%) and MSD (12%, P = .01). In multivariate analysis, MSD versus auto-SCT but not MUD versus auto-SCT was associated with lower RI (P < .01 and P = .13, respectively) and better LFS (P = .01 and P = .31, respectively). Age correlated with higher NRM (P < .01). Allo-SCT using MSD appears as a reasonable transplant option for young patients with iNPM1m AML in CR1. Auto-SCT was followed by worse RI and LFS, but similar OS to both allo-SCT modalities.

Prospective randomization of post-remission therapy comparing autologous peripheral blood stem cell transplantation versus high-dose cytarabine consolidation for acute myelogenous leukemia in first remission

We prospectively compared outcomes of autologous stem cell transplantation (ASCT) versus high-dose cytarabine (HiDAC) consolidation as post-remission therapy for favorable- and intermediate-risk acute myelogenous leukemia (AML) in first complete remission (CR1). Two-hundred-forty patients under 65 years with AML-M1, M2, M4, or M5 subtypes were enrolled. After induction, 153 patients did not undergo randomization, while the remaining 87 who achieved CR1 were prospectively randomized to HiDAC (n = 45) or ASCT arm (n = 42). In the HiDAC arm, 43 patients completed three cycles of HiDAC, whereas in ASCT arm 22 patients completed two cycles of consolidation consisting of intermediate-dose cytarabine plus mitoxantrone or etoposide followed by ASCT. The three-year disease-free survival (DFS) rate was 41% in HiDAC and 55% in ASCT arm (p = 0.25). Three-year overall survival (OS) rates were 77 and 68% (p = 0.67). Incidence of relapse was 54 and 41% (p = 0.22). There was no significant difference in nonrelapse mortality between two arms (p = 0.88). Patients in the ASCT arm tended to have higher DFS rates and lower relapse rates than patients in HiDAC; however, there was no significant improvement in OS in patients with favorable- and intermediate-risk AML in CR1. Patients with AML are not benefited by the intensified chemotherapy represented by ASCT.

Are there any new insights for G-CSF and/or AMD3100 in chemotherapy of haematological malignants?

AML is a common life-threatening blood system malignancy. The treatment of AML continues to face greater challenges. An abnormal haematopoietic niche with high adhesion and proliferation might be the root cause of resistance and relapse. Most leukaemia cells are stored in the endosteal niche and recess in the G0 phase, and they are not sensitive to varieties of radiotherapies and chemotherapies. G-CSF and AMD3100 are increasingly used in priming chemotherapy. G-CSF can promote leukaemia cells to the cell cycle, which improves the complete remission rate of leukaemia patients. AMD3100, the novel CXCR4 antagonist, could also potentially promote leukaemia cells to cell cycle and improve the susceptibility of leukaemia cells to chemotherapeutic agents. The combination of them enhances anti-leukaemia effect. So in this review, we explore the function of G-CSF and/or AMD3100 in the priming chemotherapy of haematological malignants.

In adults with t(8;21)AML, posttransplant RUNX1/RUNX1T1-based MRD monitoring, rather than c-KIT mutations, allows further risk stratification

We asked whether minimal residual disease (MRD) determined by RUNX1/RUNX1T1 transcript levels could identify allogeneic hematopoietic stem cell transplantation (allo- HSCT) t(8;21) (q22;q22) acute myeloid leukemia patients who are at high risk for relapse, together with the impact of c-KIT mutations. Ninety-two consecutive adult t(8;21) patients who received allo-HSCT in complete remission were enrolled. MRD status at 1, 2, and 3 months after HSCT identified relapse patients (P5.05, P < .001, P5.0001, respectively). The 2-year cumulative incidence of relapse (CIR) and leukemia-free survival (LFS) was 32% vs 9% (P 5 .01) and 55% vs 70% (P 5 .12) for patients with and without c-KIT mutations, respectively. In multivariate analysis, MRD at the first 3 months after HSCT, rather than c-KIT mutations,was an independent factor for CIR (P5.001) and LFS(P5.001). In addition, 17 patients received donor lymphocyte infusion (DLI) as interventional therapy for MRD, and the 2-year CIR and LFS for patients with or without DLI was 24% vs 87% (P5.001) and 64%vs 0%(P < .001), respectively. In conclusion, MRD monitoring early after transplant allows further rapid identification of t(8;21) patients at high risk of relapse and was more predictive of relapse risk than c-KIT mutations.

Complex karyotype, older age, and reduced first-line dose intensity determine poor survival in core binding factor acute myeloid leukemia patients with long-term follow-up

Approximately 40% of patients affected by core binding factor (CBF) acute myeloid leukemia (AML) ultimately die from the disease. Few prognostic markers have been identified. We reviewed 192 patients with CBF AML, treated with curative intent (age, 15-79 years) in 11 Italian institutions. Overall, 10-year overall survival (OS), disease-free survival (DFS), and event-free survival were 63.9%, 54.8%, and 49.9%, respectively; patients with the t(8;21) and inv(16) chromosomal rearrangements exhibited significant differences at diagnosis. Despite similar high complete remission (CR) rate, patients with inv(16) experienced superior DFS and a high chance of achieving a second CR, often leading to prolonged OS also after relapse. We found that a complex karyotype (i.e., ≥4 cytogenetic anomalies) affected survival, even if only in univariate analysis; the KIT D816 mutation predicted worse prognosis, but only in patients with the t(8;21) rearrangement, whereas FLT3 mutations had no prognostic impact. We then observed increasingly better survival with more intense first-line therapy, in some high-risk patients including autologous or allogeneic hematopoietic stem cell transplantation. In multivariate analysis, age, severe thrombocytopenia, elevated lactate dehydrogenase levels, and failure to achieve CR after induction independently predicted longer OS, whereas complex karyotype predicted shorter OS only in univariate analysis. The achievement of minimal residual disease negativity predicted better OS and DFS. Long-term survival was observed also in a minority of elderly patients who received intensive consolidation. All considered, we identified among CBF AML patients a subgroup with poorer prognosis who might benefit from more intense first-line treatment.

Allogeneic stem cell transplant may improve the outcome of adult patients with inv(16) acute myeloid leukemia in first complete remission with poor molecular responses to chemotherapy

Eighty-six adult patients with inv(16) acute myeloid leukemia (AML) in first complete remission (CR1) were serially monitored for CBFB-MYH11 transcript levels during the early courses of chemotherapy. Fifty-seven and 29 of them received chemotherapy/autologous stem cell transplant (SCT) and allogeneic (allo-)SCT after second consolidation, respectively. For patients receiving chemotherapy/autologous SCT, the sole independent adverse prognostic factor for the cumulative incidence of relapse (CIR), disease-free survival (DFS) and overall survival (OS) was a CBFB-MYH11 level > 0.2% after course 2 consolidation (p = 0.003, 0.003 and 0.031), which was used to define a poor molecular response (MR). Allo-SCT significantly decreased the 3-year CIR and increased the DFS and OS of patients with a poor MR (p < 0.0001, 0.0001 and 0.045) but did not improve the outcome of patients with good MR (all p > 0.05) compared with chemotherapy/autologous SCT. Therefore, allo-SCT could improve the outcome of adult patients with inv(16) AML in CR1 with a poor MR during the early courses of chemotherapy.

Core-binding factor acute myeloid leukemia: Heterogeneity, monitoring, and therapy

Core binding factor acute myelogenous leukemia (CBF AML) constitutes 15% of adult AML and carries an overall good prognosis. CBF AML encodes two recurrent cytogentic abnormalities referred to as t(8;21) and inv (16). The two CBF AML entities are usually grouped together but there is a considerable clinical, pathologic and molecular heterogeneity within this group of diseases. Recent and ongoing studies are addressing the molecular heterogeneity, minimal residual disease and targeted therapies to improve the outcome of CBF AML. In this article, we present a comprehensive review about CBF AML with emphasis on molecular heterogeneity and new therapeutic options.

Equivalent outcome of autologous stem cell transplantation and reduced intensity conditioning stem cell transplantation in acute myeloid leukemia patients with t(8;21)

We analyzed the outcome of stem cell transplantation (SCT) for 59 acute myeloid leukemia (AML) patients with t(8;21). The 5-year overall and disease-free survival (OS and DFS) were 70.2 and 68.4%, respectively. The 5-year cumulative incidence of relapse (CIR) and nonrelapse mortality were 16.9 and 13.6%, respectively. OS and DFS in the reduced-intensity conditioning (RIC)-SCT group (70.4%) were not different from in the autologous SCT (ASCT) group (72.4 and 69.0%, respectively). Age was a factor affecting OS (p = 0.007) and DFS (p = 0.008) in the ASCT group, but not in the RIC-SCT group. In the ASCT group, lack of the X chromosome (-X) and an age of >50 years were associated with inferior survival; however, these differences disappeared in the RIC-SCT group. CIR was significantly higher in patients with -X than in those without -X only in the ASCT group (p = 0.038), i.e. not in the RIC-SCT group. ASCT and RIC-SCT are equally effective for the intensification of postremission treatment of AML patients with t(8;21). The subgroups with advanced age or -X should be preferentially considered for RIC-SCT, rather than ASCT. Further investigations with randomized prospective trials of a sizeable study population are warranted.

High prognostic value of minimal residual disease detected by flow-cytometry-enhanced fluorescence in situ hybridization in core-binding factor acute myeloid leukemia (CBF-AML)

Acute myeloid leukemia (AML) is generally regarded as a disorder of stem cells, known as leukemic initiating cells (LICs), which initiate the disease and contribute to relapses. Although the phenotype of these cells remains unclear in most patients, they are enriched within the CD34(+)CD38(-) population. In core-binding factor (CBF) AML, the cytogenetic abnormalities also exist in LIC. The aim of this study was to determine the prognostic power of minimal residual disease (MRD) measured by fluorescence in situ hybridization (FISH) in CD34(+)CD38(-) cells sorted by flow cytometry at different periods during therapy. Thirty-six patients under 65 years of age with de novo CBF-AML treated with intensive chemotherapy were retrospectively included in this study. Correlations with relapse-free survival (RFS) and overall survival were evaluated with univariate and multivariate analyses. FISH efficiently identified LICs in the CD34(+)CD38(-) population. The presence of FISH(+)CD34(+)CD38(-) cells before consolidation was negatively associated with cumulative incidence of relapse (64 vs 18 %, P = .012), which showed prognostic value for RFS (12 vs 68 %, P = .008) and OS (11 vs 75 %, P = .0005), and retained prognostic significance for RFS in multivariate analysis. The detection of FISH(+)CD34(+)CD38(-) cells before consolidation therapy significantly correlated with long-term survival. Fluorescence-activated cell sorting (FACS)-FISH could be potentially adopted as a MRD monitor approach in clinical practice to identify CBF-AML patients at risk of treatment failure during therapy.

The value of allogeneic and autologous hematopoietic stem cell transplantation in prognostically favorable acute myeloid leukemia with double mutant CEBPA

The clinical value of allogeneic hematopoietic stem cell transplantation (alloHSCT) and autologous hematopoietic stem cell transplantation (autoHSCT) in the subtype of acute myeloid leukemia (AML) with double mutant CEBPA (CEBPAdm) has remained unsettled. Among 2983 patients analyzed for CEBPA mutational status (age 18-60 years) treated on 4 published Dutch-Belgian-Swiss Hemato-Oncology Cooperative Group (HOVON/SAKK) and 3 German-Austrian AML Study Group (AMLSG) protocols (2 published, 1 registered, clinicaltrials.gov NCT00151255), 124 had AML with CEBPAdm and achieved first complete remission (CR1). Evaluation of the clinical impact of alloHSCT and autoHSCT vs chemotherapy was performed by addressing time dependency in the statistical analyses. Thirty-two patients proceeded to alloHSCT from a matched related (MRD, n = 29) or a matched unrelated donor (MUD, n = 3), 20 to autoHSCT in CR1 and 72 received chemotherapy. Relapse-free survival was significantly superior in patients receiving an alloHSCT or autoHSCT in CR1 as compared with chemotherapy (P < .001), whereas overall survival was not different (P < .12). Forty-five patients relapsed. Of 42 patients treated with reinduction therapy, 35 achieved a second CR (83%) and most patients (n = 33) received an alloHSCT MRD, n = 11; MUD, n = 19; haplo-identical donor, n = 3). Survival of relapsed patients measured from date of relapse was 46% after 3 years. Adult AML patients with CEBPAdm benefit from alloHSCT and autoHSCT; relapsed patients still have a favorable outcome after reinduction followed by alloHSCT.

Old and new prognostic factors in acute myeloid leukemia with deranged core-binding factor beta

Acute myeloid leukemia (AML) with deranged core-binding factor beta (CBFβ) is usually associated with a favorable prognosis with 50-70% of patients cured using contemporary treatments. We analyzed the prognostic significance of clinical features on 58 patients with CBFβ-AML aged ≤60 years. Increasing age was the only predictor for survival (P <0.001), with an optimal cut-point at 43 years. White blood cells (WBCs) at diagnosis emerged as an independent risk factor for relapse incidence (P = 0.017), with 1.1% increase of hazard for each 1.0 × 10(9) /L WBC increment. KIT mutations lacked prognostic value for survival and showed only a trend for relapse incidence (P = 0.069).

BAALC and WT1 expressions from diagnosis to hematopoietic stem cell transplantation: consecutive monitoring in adult patients with core-binding-factor-positive AML

No consecutive analysis of BAALC and WT1 expressions associated with core-binding factor AML (CBF-AML) from diagnosis to hematopoietic stem cell transplantation (HSCT) has yet been reported. We investigated BAALC and WT1 expressions using a method of real-time quantitative polymerase chain reaction (RQ-PCR) at diagnosis, after induction chemotherapy, at pre-HSCT, and at post-HSCT period in 45 consecutive patients [t(8,21) (n = 28), inv(16) (n = 17)], who received HSCT as a post-remission treatment. BAALC and WT1 RQ-PCR decrement ratio (DR) was also calculated at post-induction chemotherapy, at pre-HSCT, and at post-HSCT compared with the diagnostic level. Higher BAALC expression at diagnosis showed significantly inferior OS (P = 0.031), EFS (P = 0.011), and higher CIR (P = 0.002) rates. At post-HSCT, both higher BAALC and WT1 expressions showed significantly inferior OS (P = 0.005, 0.016), EFS (P = 0.002, 0.006), and higher CIR (P = 0.001, 0.003) rates. A subgroup of t(8;21) showing higher BAALC and WT1 expressions at post-HSCT were also associated with inferior OS (P = 0.018, 0.015) and higher CIR rates (P = 0.019, 0.011). While BAALC DR showed no significant results on outcomes, WT1 DR more than 2-log at post-HSCT showed significantly lower CIR rate (P = 0.028). This study showed that higher post-HSCT BAALC and WT1 expressions in patients with CBF-AML may be good markers of minimal residual disease for the prediction of survival and relapse after HSCT.

MRD-directed risk stratification treatment may improve outcomes of t(8;21) AML in the first complete remission: results from the AML05 multicenter trial

We aimed to improve the outcome of t(8;21) acute myeloid leukemia (AML) in the first complete remission (CR1) by applying risk-directed therapy based on minimal residual disease (MRD) determined by RUNX1/RUNX1T1 transcript levels. Risk-directed therapy included recommending allogeneic hematopoietic stem cell transplantation (allo-HSCT) for high-risk patients and chemotherapy/autologous-HSCT (auto-HSCT) for low-risk patients. Among 116 eligible patients, MRD status after the second consolidation rather than induction or first consolidation could discriminate high-risk relapse patients (P = .001). Allo-HSCT could reduce relapse and improve survival compared with chemotherapy for high-risk patients (cumulative incidence of relapse [CIR]: 22.1% vs 78.9%, P < .0001; disease-free survival [DFS]: 61.7% vs 19.6%, P = .001), whereas chemotherapy/auto-HSCT achieved a low relapse rate (5.3%) and high DFS (94.7%) for low-risk patients. Multivariate analysis revealed that MRD status and treatment choice were independent prognostic factors for relapse, DFS, and OS. We concluded that MRD status after the second consolidation may be the best timing for treatment choice. MRD-directed risk stratification treatment may improve the outcome of t(8;21) AML in CR1. This trial was registered at http://www.chictr.org as #ChiCTR-OCH-12002406.

Core-binding factor acute myeloid leukemia: can we improve on HiDAC consolidation?

Acute myeloid leukemia (AML) with t(8;21) or inv(16) is commonly referred to as core-binding factor AML (CBF-AML). The incorporation of high-dose cytarabine for postremission therapy has substantially improved the outcome of CBF-AML patients, especially when administered in the setting of repetitive cycles. For many years, high-dose cytarabine was the standard treatment in CBF-AML resulting in favorable long-term outcome in approximately half of the patients. Therefore, CBF-AML patients are generally considered to be a favorable AML group. However, a substantial proportion of patients cannot be cured by the current treatment. Additional genetic alterations discovered in CBF-AML help in our understanding of the process of leukemogenesis and some of them may refine the risk assessment in CBF-AML and, importantly, also serve as targets for novel therapeutic approaches. We discuss the clinical and genetic heterogeneity of CBF-AML, with a particular focus on the role of KIT mutations as a prognosticator, and also discuss recent efforts to target the KIT kinase in the context of existing therapeutic regimens.

Therapy of core binding factor acute myeloid leukemia: incremental improvements toward better long-term results

Despite being considered as good prognostic acute myelogenous leukemia (AML), the long-term survival rate in core binding factor AML leaves room for substantial improvement. We discuss treatments that have improved outcome in this group of patients with AML and ongoing/future strategies that might contribute toward incremental gains.

BACKGROUND

Despite being considered as good prognostic acute myelogenous leukemia (AML), the long-term survival rate in core binding factor (CBF) AML leaves room for substantial improvement.

MATERIALS AND METHODS

We reviewed relevant English language literature related to treatment of CBF AML available in PubMed. Review also included meeting abstracts.

RESULTS

Multicycle high dose cytarabine in consolidation improves remission duration but larger groups report overall survival in the range of 40% to 50% at 5 years or longer.

CONCLUSIONS

Concerted effort is needed toward improving outcomes in CBF AML through clinical trials and risk-adapted approach.

Role of autologous hematopoietic stem cell transplantation according to the NPM1/FLT3-ITD molecular status for cytogenetically normal AML patients: a GOELAMS study

The choice of postremission therapy for acute myeloid leukemia (AML) patients is now based on the blasts' cytogenetic and molecular profile. However, the potential benefit of autologous hematopoietic stem cell transplantation (auto-HSCT) according to the NPM1/FLT3-ITD status has been poorly studied in AML patients with a normal karyotype (NK). Therefore, we evaluated the NPM1/FLT3-ITD molecular status in 135 NK-AML patients treated by allogeneic HSCT (allo-HSCT), auto-HSCT, or chemotherapy as consolidation therapy within the GOELAMS LAM-2001 trial. In univariate analyzes, 4-year leukemia-free survival (LFS) and overall survival (OS) were significantly higher for NPM1+/FLT3-ITD- patients compared with patients presenting another molecular profile (61 vs. 43% and 72 vs. 48%, P = 0.02 and P = 0.01, respectively). In the NPM1+/FLT3-ITD- subgroup, there was no benefit for allo-HSCT or auto-HSCT vs. chemotherapy (4-year LFS: 71, 56, and 60%; 4-year OS: 73, 71, and 60%, respectively; P = NS). For patients with other NPM1/FLT3-ITD molecular profiles, allo-HSCT was found to be the best consolidation therapy, whereas auto-HSCT was associated with a better outcome when compared with chemotherapy (allo-HSCT-, auto-HSCT-, and chemotherapy-related 4-year LFS: 68, 44, and 36%, P = 0.004; 4-year OS: 68, 52, and 29%, respectively, P = 0.02). Our study indicates that allo-HSCT and auto-HSCT provide similar outcomes compared with chemotherapy as consolidation for NPM1+/FLT3-ITD- NK-AML patients. For NK-AML patients with an adverse molecular profile, auto-HSCT could represent an alternative therapeutic approach when no human leukocyte antigen-matched allogeneic donor is available.

Bortezomib interferes with C-KIT processing and transforms the t(8;21)-generated fusion proteins into tumor-suppressing fragments in leukemia cells

The boronic acid dipeptide bortezomib inhibits the chymotrypsin-like activity of the 26S proteasome and shows significant therapeutic efficacy in multiple myeloma. However, recent studies suggest that bortezomib may have more complex mechanisms of action in treating cancer. We report here that the endocytosis and lysosomal degradation of the receptor tyrosine kinase C-KIT are required for bortezomib- but not tyrosine kinase inhibitor imatinib-caused apoptosis of t(8;21) leukemia and gastrointestinal stromal tumor cells, suggesting that C-KIT may recruit an apoptosis initiator. We show that C-KIT binds and phosphorylates heat shock protein 90β (Hsp90β), which sequestrates apoptotic protease activating factor 1 (Apaf-1). Bortezomib dephosphorylates pHsp90β and releases Apaf-1. Although the activated caspase-3 is not sufficient to cause marked apoptosis, it cleaves the t(8;21) generated acute myeloid leukemia 1-eight twenty one (AML1-ETO) and AML1-ETO9a fusion proteins, with production of cleavage fragments that perturb the functions of the parental oncoproteins and further contribute to apoptosis. Notably, bortezomib exerts potent therapeutic efficacy in mice bearing AML1-ETO9a-driven leukemia. These data show that C-KIT-pHsp90β-Apaf-1 cascade is critical for some malignant cells to evade apoptosis, and the clinical therapeutic potentials of bortezomib in C-KIT-driven neoplasms should be further explored.

Classifying cytogenetics in patients with acute myelogenous leukemia in complete remission undergoing allogeneic transplantation: a Center for International Blood and Marrow Transplant Research study

Cytogenetics play a major role in determining the prognosis of patients with acute myelogenous leukemia (AML). However, existing cytogenetics classifications were developed in chemotherapy-treated patients and might not be optimal for patients undergoing allogeneic hematopoietic cell transplantation (HCT). We studied 821 adult patients reported to the Center for International Blood and Marrow Transplant Research (CIBMTR) who underwent HCT for AML in first or second complete remission between 1999 and 2004. We compared the ability of the 6 existing classifications to stratify patients by overall survival. We then defined a new scheme specifically applicable to patients undergoing HCT using this patient cohort. Under this scheme, inv(16) is favorable, a complex karyotype (4 or more abnormalities) is adverse, and all other classified abnormalities are intermediate in predicting survival after HCT (5-year overall survival, 64%, 18%, and 50%, respectively; P = .0001). This scheme stratifies patients into 3 groups with similar nonrelapse mortality, but significantly different incidences of relapse, overall and leukemia-free survival. It applies to patients regardless of disease status (first or second complete remission), donor type (matched related or unrelated), or conditioning intensity (myeloablative or reduced intensity). This transplantation-specific classification could be adopted for prognostication purposes and to stratify patients with AML and karyotypic abnormalities entering HCT clinical trials.

Acute myeloid leukemia with the t(8;21) translocation: clinical consequences and biological implications

The t(8;21) abnormality occurs in a minority of acute myeloid leukemia (AML) patients. The translocation results in an in-frame fusion of two genes, resulting in a fusion protein of one N-terminal domain from the AML1 gene and four C-terminal domains from the ETO gene. This protein has multiple effects on the regulation of the proliferation, the differentiation, and the viability of leukemic cells. The translocation can be detected as the only genetic abnormality or as part of more complex abnormalities. If t(8;21) is detected in a patient with bone marrow pathology, the diagnosis AML can be made based on this abnormality alone. t(8;21) is usually associated with a good prognosis. Whether the detection of the fusion gene can be used for evaluation of minimal residual disease and risk of leukemia relapse remains to be clarified. To conclude, detection of t(8;21) is essential for optimal handling of these patients as it has both diagnostic, prognostic, and therapeutic implications.

Salvage chemotherapy with low-dose cytarabine and aclarubicin in combination with granulocyte colony-stimulating factor priming in patients with refractory or relapsed acute myeloid leukemia with translocation (8;21)

High expression levels of granulocyte colony stimulating factor (G-CSF) receptor were found in the leukemic cells of acute myeloid leukemia (AML) patients with t(8;21). Therapeutic significance of G-CSF receptor on chemotherapy remains to be defined. We evaluate the efficacy and tolerability of CAG regimen, consisting of concurrent use of G-CSF with low-dose cytarabine and aclarubicin, in 36 refractory/relapsed AML patients with t(8;21). The overall complete remission (CR) rate was 75% and median CR duration was 12 months. No significant treatment-related adverse events were observed. These data demonstrate that CAG regimen might be an alternative option in the treatment of AML with t(8;21), especially in older patients or patients with co-morbidities.

Prognostic factors and outcomes of adult patients with acute myeloid leukemia after first relapse

BACKGROUND

Patients with acute myeloid leukemia who are treated with conventional chemotherapy still have a substantial risk of relapse; the prognostic factors and optimal treatments after relapse have not been fully established. We, therefore, retrospectively analyzed data from patients with acute myeloid leukemia who had achieved first complete remission to assess their prognosis after first relapse.

DESIGN AND METHODS

Clinical data were collected from 70 institutions across the country on adult patients who were diagnosed with acute myeloid leukemia and who had achieved a first complete remission after one or two courses of induction chemotherapy.

RESULTS

Among the 1,535 patients who were treated with chemotherapy alone, 1,015 relapsed. Half of them subsequently achieved a second complete remission. The overall survival was 30% at 3 years after relapse. Multivariate analysis showed that achievement of second complete remission, salvage allogeneic hematopoietic cell transplantation, and a relapse-free interval of 1 year or longer were independent prognostic factors. The outcome after allogeneic transplantation in second complete remission was comparable to that after transplantation in first complete remission. Patients with acute myeloid leukemia and cytogenetic risk factors other than inv(16) or t(8;21) had a significantly worse outcome when they did not undergo salvage transplantation even when they achieved second complete remission.

CONCLUSIONS

We found that both the achievement of second complete remission and the application of salvage transplantation were crucial for improving the prognosis of patients with acute myeloid leukemia in first relapse. Our results indicate that the optimal treatment strategy after first relapse may differ according to the cytogenetic risk.