GIMEMA AML1310 trial of risk-adapted, MRD-directed therapy for young adults with newly diagnosed acute myeloid leukemia

Measurable residual disease assessment prior to allogeneic hematopoietic stem cell transplantation in acute myeloid leukemia and myelodysplastic syndromes: a 20-year monocentric study

Patients with acute myeloid leukemia (AML) or myelodysplastic syndromes (MDS) who undergo allogeneic hematopoietic stem-cell transplantation (alloHSCT) can have divergent survival outcomes while all in morphological complete remission (CR). Techniques of measurable residual disease (MRD) have allowed us to refine their prognosis in two categories: MRD-positive and MRD-negative patients. We conducted a monocentric retrospective study (01/2000-12/2020) to assess the prognosis of pretransplant MRD status measured by multiparametric flow cytometry (MFC) and molecular biology assessed by PCR. 192 patients were included. The median follow-up period was 77 months. Among patients undergoing alloHSCT in CR, overall survival (median-OS: 130.6 vs. 16.0 months, P < 0.001), disease-free survival (median-DFS: 109.6 vs. 7.1 months, P < 0.001) and cumulative incidence of relapse (12-month CIR: 7.3% vs. 33.7%, P < 0.0001) were significantly different between MRD-negative and MRD-positive patients. Patients with discordant intermethod results had intermediate DFS. MRD-negative patients according to molecular PCR-based techniques, WT1 overexpression and MFC had longer median-DFS, compared to MRD-positive patients (P = 0.001, P < 0.001, P < 0.001, respectively). Looking into subgroups, MRD-positive patients among the ELN2017 adverse-category (P < 0.0001), myeloablative and reduced-intensity conditioning regimens (P < 0.0001, P = 0.005), < 60-year patients (P < 0.001) and AML patients (P < 0.001) were associated with lower DFS. This difference was not found in ≥ 60-year patients (P = 0.27) and MDS patients (P = 0.70). MRD-positive patients within the favorable/intermediate ELN2017 category trended toward lower DFS (P = 0.05). We confirmed that MRD status prior to alloHSCT is a strong prognostic factor for OS, DFS and CIR. Combining MFC and molecular-PCR techniques to assess MRD seems primordial as inter-method discordance can be consequential.

Indeterminate measurable residual disease by multiparameter flow cytometry is associated with an intermediate risk of clinical relapse in adult patients with acute leukaemia

Measurable residual disease (MRD) is useful for prognostication and for monitoring response to treatment in patients with acute leukaemia. MRD by multiparametric flow cytometry (MFC-MRD) utilises the leukaemia-associated immunophenotype (LAIP) and difference from normal (DfN) strategies to identify the leukaemic clone. Difficulties arise when the LAIP overlaps with normal regeneration, there is clonal evolution, or when the abnormal clone population is exceptionally small e.g., <0.01% of CD45+ cells. Such cases are reported as 'indeterminate'; however, there is little international consensus on this reporting. The relationship between clinical outcomes and indeterminate MFC-MRD is unknown. Here we determine the rate of indeterminate MFC-MRD reporting, its relationship to concurrent molecular MRD results when available, and to clinical outcomes to 12 months. We performed an internal audit of all adult testing for MFC-MRD between January and December 2021. A total of 153 consecutive patients with a diagnosis of acute leukaemia were included. Successive MFC-MRD results and clinical outcomes were recorded over a 12-month period from time of inclusion into the study. In total, 460 MFC-MRD tests from 153 patients were reviewed and 73 (16%) MFC-MRD tests from 54 (35%) patients were reported as indeterminate. The majority (70%) were at low levels between 0.01-0.1% of CD45+ cells. Compared to patients with a negative result, acute myeloid leukaemia (AML) was more frequent in patients who had an indeterminate MFC-MRD (70% vs 36%), and B-cell acute lymphoblastic leukaemia was less common (20% vs 55%). In patients with indeterminate MFC-MRD results, one-third had received either chemotherapy or allogeneic haemopoietic stem cell transplant (aHSCT) within the preceding 3 months. Agreement between MFC and molecular MRD testing was low. Patients with indeterminate MFC-MRD had leukaemia relapse rates below patients with a positive MFC-MRD, but greater than those with negative MFC-MRD (positive 33% vs indeterminate 21% vs negative 8%, p = 0.038). Overall, these findings indicate that indeterminate MFC-MRD results are more common in adults with AML and also in those who have received chemotherapy or aHSCT within the previous 3 months. We report for the first time that indeterminate MFC-MRD is a finding of potential clinical significance, which associates with a numerically higher median relapse rate within 12 months when compared to a negative MFC-MRD result.

Auto-hematopoietic stem cell transplantation or chemotherapy? Meta-analysis of clinical choice for AML

For patients with acute myeloid leukemia (AML) who are not candidates for allogeneic stem cell transplantation (SCT) or do not have a human leukocyte antigen (HLA)-matched donor, it is unclear whether autologous SCT (ASCT) has a better prognosis after the first complete response (CR1) compared to further chemotherapy treatment. A meta-analysis evaluating ASCT compared to further chemotherapy for AML patients in CR1 was performed. The Medline, Embase, Cochrane Controlled Trials Registry, Cochrane Library, Web of Science, and National Knowledge Infrastructure of China databases were searched for relevant literature as of May 26, 2023. Eligible studies included prospectively enrolled adults with AML and randomized first-time respondent patients who did not have a matched sibling donor. Fourteen randomized controlled trials were identified and included 4281 participants, of which 1499 patients received ASCT and 2782 underwent chemotherapy and continued follow-up. In patients with AML in CR1, a lower relapse rate was associated with ASCT compared to chemotherapy [odds ratio (OR) = 0.49, 95% confidence interval (CI) = 0.41-0.57]. Significant disease-free survival (DFS; OR = 1.37, 95% CI = 1.02-1.84) and relapse-free survival (RFS; OR = 2.78, 95% CI = 1.28-6.02) ASCT benefits were documented, and there was no difference in the overall survival (OS) when the studies were pooled (OR = 1.12, 95% CI = 0.85-1.48). The study results indicated that after the first remission, AML patients receiving autologous stem cell transplantation had higher DFS and RFS, similar OS, and lower relapse compared to patients undergoing chemotherapy treatment. This indicated that autologous stem cell transplantation may have a better prognosis.

Immunophenotypic markers for the evaluation of minimal/measurable residual disease in acute megakaryoblastic leukemia

Acute megakaryoblastic leukemia is characterized by heterogeneous biology and clinical behavior. Immunophenotypic characteristics include the expression of megakaryocytic differentiation markers (e.g. CD41, CD42a, CD42b, CD61) associated with immaturity markers (CD34, CD117, HLA-DR) and myeloid markers (e.g. CD13, CD33) and even with lymphoid cross-lineage markers (e.g. CD7, CD56). Although the diagnostic immunophenotype has already been well described, given the rarity of the disease, its immunophenotypic heterogeneity and post-therapeutic instability, there is no consensus on the combination of monoclonal markers to detect minimal/measurable residual disease (MRD). Currently, MRD is an important tool for assessing treatment efficacy and prognostic risk. In this study, we evaluated the immunophenotypic profile of MRD in a retrospective cohort of patients diagnosed with acute megakaryoblastic leukemia, to identify which markers, positive or negative, were more stable after treatment and which could be useful for MRD evaluation. The expression profile of each marker was evaluated in sequential MRD samples. In conclusion, the markers evaluated in this study can be combined in an MRD immunophenotypic panel to investigate for megakaryoblastic leukemia. Although this study is retrospective and some data are missing, the information obtained may contribute to prospective studies to validate more specific strategies in the detection of MRD in acute megakaryoblastic leukemia.

Measurable residual disease monitoring in AML: Prospects for therapeutic decision-making and new drug development

Measurable residual disease (MRD) is strongly associated with risk of relapse and long-term survival outcomes in patients with acute myeloid leukemia (AML). Apart from its clear prognostic impact, MRD information is also increasingly used to guide therapeutic decision-making, including selection of appropriate patients for stem cell transplant, use of post-transplant maintenance, and candidacy for non-transplant maintenance therapies or MRD-directed clinical trials. While much progress has been made in accurately assessing MRD and understanding its clinical importance, many questions remain about how to optimize MRD testing and guide treatment decisions for individual patients. In this review, we discuss the common methods to assess MRD in AML and the prognostic impact of MRD across common clinical scenarios. We also review emerging and investigational strategies to target MRD and discuss some of the important unanswered questions and challenges in the field.

Unsupervised Clustering Analysis of Regimen and HLA Characteristics in Pediatric Umbilical Cord Blood Transplantation

HLA matching is a critical factor in allogeneic unrelated hematopoietic cell transplantation (HCT) because of its impact on post-transplantation survival and quality of life. Umbilical cord blood transplantation (UCBT) offers unique advantages, but determining the optimal approach to graft selection and immunosuppression remains challenging. Unsupervised clustering, a machine learning technique, has potential for analyzing transplantation outcomes, but its application in investigating leukemia outcomes has been limited. This study aimed to identify optimal combinations of HLA/ killer immunoglobulin receptor (KIR) donor-patient pairing, conditioning, and immunosuppressive regimens in pediatric patients with acute lymphoblastic leukemia (ALL) or acute myeloblastic leukemia (AML) undergoing UCBT. Outcome data for single, unmanipulated UCBT in pediatric AML (n = 708) and ALL (n = 1034) patients from the Eurocord/EBMT registry were analyzed using unsupervised clustering. Resulting clusters were used to inform post hoc competing risks and Kaplan-Meier analyses. In AML, single HLA-C mismatches with other loci fully matched (7/8) were associated with poorer relapse-free survival (RFS) (P = .039), but a second mismatch at any other locus counteracted this effect. In ALL, total body irradiation (TBI) effectively prevented relapse mortality (P = .007). KIR/HLA-C match status affected RFS in AML (P = .039) but not in ALL (P = .8). Administration of antithymocyte globulin (ATG) substantially increased relapse, with no relapses occurring in the 85 patients who did not receive ATG. Our unsupervised clustering analyses generate several key statistical and mechanistic hypotheses regarding the relationships between HLA matching, conditioning regimens, immunosuppressive therapies, and transplantation outcomes in pediatric AML and ALL patients. HLA-C and KIR combinations significantly impact RFS in pediatric AML but not in ALL. ATG use in fully matched pediatric patients is associated with late-stage relapse. TBI regimens appear to be beneficial in ALL, with efficacy largely independent of histocompatibility variables. These findings reflect the distinct genetic and biological profiles of AML and ALL.

Measurable residual disease (MRD)-testing in haematological cancers: A giant leap forward or sideways?

Measurable residual disease (MRD)-testing is used in many haematological cancers to estimate relapse risk and to direct therapy. Sometimes MRD-test results are used for regulatory approval. However, some people including regulators wrongfully believe results of MRD-testing are highly accurate and of proven efficacy in directing therapy. We review MRD-testing technologies and evaluate the accuracy of MRD-testing for predicting relapse and the strength of evidence supporting efficacy of MRD-guided therapy. We show that at the individual level MRD-test results are often an inaccurate relapse predictor. Also, no convincing data indicate that increasing therapy-intensity based on a positive MRD-test reduces relapse risk or improves survival. We caution against adjusting therapy-intensity based solely on results of MRD-testing.

Optimizing maintenance therapy in acute myeloid leukemia: where do we stand in the year 2024?

INTRODUCTION

Despite the prognosis of patients affected by acute myeloid leukemia (AML) improved in the last decade, most patients relapse. Maintenance therapy after a chemotherapy approach with or without allogeneic stem cell transplantation could be a way to control the undetectable residual burden of leukemic cells. Several studies are being carried out as maintenance therapy in AML. Some critical points need to be defined, how the physician can choose among the various drugs available.

AREAS COVERED

This review discusses the advances and controversies surrounding maintenance therapy for AML patients.

EXPERT OPINION

Patients withFLT3-positive AML should receive midostaurin or quizartinib in the first-linesetting. For a patient initially receiving midostaurin, consider switching to sorafenib in the post-transplant setting. Because of the improved safety profile and potency, many experts will lean toward using a second-generation FLT3 inhibitor such as quizartinib or gilteritinib. Finally, no data indicate whether maintenance therapy should be prolonged until progression or for a defined period.

Immunophenotypic features of early haematopoietic and leukaemia stem cells

Many tumours are organised in a hierarchical structure with at its apex a cell that can maintain, establish, and repopulate the tumour-the cancer stem cell. The haematopoietic stem cell (HSC) is the founder cell for all functional blood cells. Like HSCs, the leukaemia stem cells (LSC) are hypothesised to be the leukaemia-initiating cells, which have features of stemness such as self-renewal, quiescence, and resistance to cytotoxic drugs. Immunophenotypically, CD34+CD38- defines HSCs by adding lineage negativity and CD90+CD45RA-. At which stage of maturation the further differentiation is blocked, determines the type of leukaemia, and determines the immunophenotype of the LSC specific to the leukaemia type. No apparent LSC phenotype has been described in lymphoid leukaemia, and it is debated if a specific acute lymphocytic leukaemia-initiating cell is present, as all cells are capable of engraftment in a secondary mouse model. In chronic lymphocytic leukaemia, a B-cell clone is responsible for uncontrolled proliferation, not a specific LSC. In chronic and acute myeloid leukaemia, LSC is described as CD34+CD38- with the expression of a marker that is aberrantly expressed (LSC marker), such as CD45RA, CD123 or in the case of chronic myeloid leukaemia CD26. In acute myeloid leukaemia, the LSC load had prognostic relevance and might be a biomarker that can be used for monitoring and as an addition to measurable residual disease. However, challenges such as the CD34-negative immunophenotype need to be explored.

Reduced toxicity (FluBu3) versus myeloablative (BuCy) conditioning in acute myeloid leukemia patients who received first allogeneic hematopoietic stem cell transplantation in measurable residual disease-negative CR1

In the present study, reduced toxicity (FluBu3) and myeloablative (BuCy) conditioning were compared in patients with AML who received first allogeneic HSCT in MRD-negative CR1. The study included 124 adult patients who underwent HSCT from an HLA-matched (8/8) sibling, unrelated, or 1-locus mismatched (7/8) unrelated donor (MMUD). The median age was 45 years and intermediate cytogenetics comprised majority (71.8%). The 2-year OS, RFS, CIR and NRM for BuCy (n = 78, 62.9%) and FluBu3 (n = 46, 37.1%) groups were 78.3% and 84.5% (p = 0.358), 78.0% and 76.3% (p = 0.806), 7.7% and 21.5% (p = 0.074) and 14.3% and 2.2% (p = 0.032), respectively. At the time of data cut-off, relapse and NRM were the main causes of HSCT failure in each of the FluBu3 and BuCy arms. Among patients, 75% of relapsed FluBu3 patients had high-risk features of either poor cytogenetics or FLT3-ITD mutation compared with 16.7% of BuCy patients. The majority of NRM in the BuCy group was due to GVHD (73%), half of whom received MMUD transplantation. To conclude, the FluBu3 reduced toxicity conditioning showed comparable post-transplant OS and RFS to BuCy and was associated with significantly reduced NRM that was offset by a trend towards higher risk of relapse even in MRD-negative CR1 population.

Comparison of allo-SCT, auto-SCT and chemotherapy for the treatment of patients with low- or intermediate-risk acute myeloid leukemia: a network meta-analysis

BACKGROUND

The therapeutic status of allogeneic stem cell transplantation (allo-SCT) as a post-remission treatment for patients with high-risk acute myeloid leukemia (AML) was well-accepted. However, the optimal treatment for patients with low/favorable- or intermediate-risk AML who achieve complete remission has remained controversial. Therefore, we conducted a network meta-analysis to discuss this disputed problem.

METHODS

We compared the effects of treatment strategies including allo-SCT, autologous stem cell transplantation (auto-SCT) and consolidation chemotherapy (CT) for patients with low/favorable- or intermediate-risk AML. The pooled HRs and 95% CIs for overall survival and disease-free survival were estimated with Stata12 and R software. Thirty clinical studies with 6682 patients were included in the meta-analysis.

RESULTS

The results indicated that the treatment outcome of allo-SCT was the best, followed by auto-SCT, and CT was likely the worst in the total AML patients. In patients with low/favorable-risk AML, the treatment outcome of auto-SCT was likely ranked first, followed by allo-SCT, and CT was the worst. In patients with intermediate-risk AML, the treatment outcome of haploidentical stem cell transplantation (haplo-SCT) was the best, followed by allo-SCT (excluding haplo-SCT), and auto-SCT and CT were the worst. However, the median age of the haplo-SCT group was much younger than that of the control group, which may be one of the reasons for the better prognosis of the haplo-SCT group.

CONCLUSIONS

Patients with low/favorable- and intermediate-risk (non-high-risk) AML should prioritize allo-SCT if they are eligible for transplantation, and auto-SCT is optional. However, in the subgroup analysis, auto-SCT was the optimal treatment choice for patients with low/favorable-risk AML, and allo-SCT was the priority selection for patients with intermediate-risk AML, especially young patients. These findings could provide references for clinical practice.

Unlocking the potential of synthetic patients for accelerating clinical trials: Results of the first GIMEMA experience on acute myeloid leukemia patients

Artificial Intelligence has the potential to reshape the landscape of clinical trials through innovative applications, with a notable advancement being the emergence of synthetic patient generation. This process involves simulating cohorts of virtual patients that can either replace or supplement real individuals within trial settings. By leveraging synthetic patients, it becomes possible to eliminate the need for obtaining patient consent and creating control groups that mimic patients in active treatment arms. This method not only streamlines trial processes, reducing time and costs but also fortifies the protection of sensitive participant data. Furthermore, integrating synthetic patients amplifies trial efficiency by expanding the sample size. These straightforward and cost-effective methods also enable the development of personalized subject-specific models, enabling predictions of patient responses to interventions. Synthetic data holds great promise for generating real-world evidence in clinical trials while upholding rigorous confidentiality standards throughout the process. Therefore, this study aims to demonstrate the applicability and performance of these methods in the context of onco-hematological research, breaking through the theoretical and practical barriers associated with the implementation of artificial intelligence in medical trials.

Flow cytometry-based measurable residual disease (MRD) analysis identifies AML patients who may benefit from allogeneic hematopoietic stem cell transplantation

Measurable residual disease (MRD) monitoring independently predicts long-term outcomes in patients with acute myeloid leukemia (AML). Of the various modalities available, multiparameter flow cytometry-based MRD analysis is widely used and relevant for patients without molecular targets. In the transplant (HCT) setting, the presence of MRD pre-HCT is associated with adverse outcomes. MRD-negative remission status pre-HCT was also associated with longer overall (OS) and progression-free survival and a lower risk of relapse. We hypothesize that the combination of disease risk and MRD at the time of first complete remission (CR1) could identify patients according to the benefit gained from HCT, especially for intermediate-risk patients. We performed a retrospective analysis comparing the outcomes of HCT versus non-HCT therapies based on MRD status in AML patients who achieved CR1. Time-dependent analysis was applied considering time-to-HCT as a time-dependent covariate and compared HCT versus non-HCT outcomes according to MRD status at CR1. Among 336 patients assessed at CR1, 35.1% were MRD positive (MRDpos) post-induction. MRDpos patients benefitted from HCT with improved OS and relapse-free survival (RFS), while no benefit was observed in MRDneg patients. In adverse-risk patients, HCT improved OS (HR for OS 0.55; p = 0.05). In intermediate-risk patients, HCT benefit was not significant for OS and RFS. Intermediate-risk MRDpos patients were found to have benefit from HCT with improved OS (HR 0.45, p = 0.04), RFS (HR 0.46, p = 0.02), and CIR (HR 0.41, p = 0.02). Our data underscore the benefit of HCT in adverse risk and MRDpos intermediate-risk AML patients.

Innovations in conditioning and post-transplant maintenance in AML: genomically informed revelations on the graft-versus-leukemia effect

Acute Myeloid Leukemia (AML) is the prototype of cancer genomics as it was the first published cancer genome. Large-scale next generation/massively parallel sequencing efforts have identified recurrent alterations that inform prognosis and have guided the development of targeted therapies. Despite changes in the frontline and relapsed standard of care stemming from the success of small molecules targeting FLT3, IDH1/2, and apoptotic pathways, allogeneic stem cell transplantation (alloHSCT) and the resulting graft-versus-leukemia (GVL) effect remains the only curative path for most patients. Advances in conditioning regimens, graft-vs-host disease prophylaxis, anti-infective agents, and supportive care have made this modality feasible, reducing transplant related mortality even among patients with advanced age or medical comorbidities. As such, relapse has emerged now as the most common cause of transplant failure. Relapse may occur after alloHSCT because residual disease clones persist after transplant, and develop immune escape from GVL, or such clones may proliferate rapidly early after alloHSCT, and outpace donor immune reconstitution, leading to relapse before any GVL effect could set in. To address this issue, genomically informed therapies are increasingly being incorporated into pre-transplant conditioning, or as post-transplant maintenance or pre-emptive therapy in the setting of mixed/falling donor chimerism or persistent detectable measurable residual disease (MRD). There is an urgent need to better understand how these emerging therapies modulate the two sides of the GVHD vs. GVL coin: 1) how molecularly or immunologically targeted therapies affect engraftment, GVHD potential, and function of the donor graft and 2) how these therapies affect the immunogenicity and sensitivity of leukemic clones to the GVL effect. By maximizing the synergistic action of molecularly targeted agents, immunomodulating agents, conventional chemotherapy, and the GVL effect, there is hope for improving outcomes for patients with this often-devastating disease.

Impact of hemodilution on flow cytometry based measurable residual disease assessment in acute myeloid leukemia

Measurable residual disease (MRD) measured in the bone marrow (BM) of acute myeloid leukemia (AML) patients after induction chemotherapy is an established prognostic factor. Hemodilution, stemming from peripheral blood (PB) mixing within BM during aspiration, can yield false-negative MRD results. We prospectively examined hemodilution by measuring MRD in BM aspirates obtained from three consecutive 2 mL pulls, along with PB samples. Our results demonstrated a significant decrease in MRD percentages between the first and second pulls (P = 0.025) and between the second and third pulls (P = 0.025), highlighting the impact of hemodilution. Initially, 39% of MRD levels (18/46 leukemia-associated immunophenotypes) exceeded the 0.1% cut-off, decreasing to 30% (14/46) in the third pull. Additionally, we assessed the performance of six published methods and parameters for distinguishing BM from PB samples, addressing or compensating for hemodilution. The most promising results relied on the percentages of CD16dim granulocytic population (scarce in BM) and CD117high mast cells (exclusive to BM). Our findings highlight the importance of estimating hemodilution in MRD assessment to qualify MRD results, particularly near the common 0.1% cut-off. To avoid false-negative results by hemodilution, it is essential to collect high-quality BM aspirations and preferably utilizing the initial pull for MRD testing.

Minimal Residual Disease in Acute Myeloid Leukemia: Old and New Concepts

Minimal residual disease (MRD) is of major importance in onco-hematology, particularly in acute myeloid leukemia (AML). MRD measures the amount of leukemia cells remaining in a patient after treatment, and is an essential tool for disease monitoring, relapse prognosis, and guiding treatment decisions. Patients with a negative MRD tend to have superior disease-free and overall survival rates. Considerable effort has been made to standardize MRD practices. A variety of techniques, including flow cytometry and molecular methods, are used to assess MRD, each with distinct strengths and weaknesses. MRD is recognized not only as a predictive biomarker, but also as a prognostic tool and marker of treatment efficacy. Expected advances in MRD assessment encompass molecular techniques such as NGS and digital PCR, as well as optimization strategies such as unsupervised flow cytometry analysis and leukemic stem cell monitoring. At present, there is no perfect method for measuring MRD, and significant advances are expected in the future to fully integrate MRD assessment into the management of AML patients.

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.

Prognostic value of postinduction medullary myeloid recovery by flow cytometry in acute myeloid leukemia

Risk stratification and treatment response evaluation are key features in acute myeloid leukemia (AML) management. Immunophenotypic and molecular approaches all rely on the detection of persisting leukemic cells by measurable residual disease techniques. A new approach is proposed here by assessing medullary myeloid maturation by flow cytometry through a myeloid progenitor ratio (MPR). The normal MPR range was defined using reference normal bone marrows (n = 48). MPR was considered balanced if between 1 and 4 and unbalanced if < 1 or > 4. MPR was retrospectively assessed at baseline and post-induction for 206 newly diagnosed AML patients eligible for intensive treatment from two different French centers. All AML baseline MPR were unbalanced and thus significantly different from normal MPR (p < 0.0001). Patients with an unbalanced MPR after induction had worse 3-year overall survival (OS) (44.4% vs. 80.2%, HR, 2.96; 95% CI, 1.81-4.84, p < 0.0001) and 3-year relapse free survival (RFS) (38.7% vs. 64.4%, HR, 2.11; 95% CI, 1.39-3.18, p < 0.001). In multivariate analysis, postinduction unbalanced MPR was significantly associated with shorter OS and RFS regardless of the European LeukemiaNet 2010 risk stratification or NPM1/FLT3-ITD status. A balanced postinduction MPR conversely conferred favorable outcomes and reflects medullary myeloid recovery.

Criteria for Diagnosis and Molecular Monitoring of NPM1-Mutated AML

NPM1-mutated acute myeloid leukemia (AML) represents the largest molecular subgroup of adult AML. NPM1-mutated AML is recognizable by molecular techniques and immunohistochemistry, which, when combined, can solve difficult diagnostic problems (including identification of myeloid sarcoma and NPM1 mutations outside exon 12). According to updated 2022 European LeukemiaNet (ELN) guidelines, determining the mutational status of NPM1 (and FLT3) is a mandatory step for the genetic-based risk stratification of AML. Monitoring of measurable residual disease (MRD) by qRT-PCR, combined with ELN risk stratification, can guide therapeutic decisions at the post-remission stage. Here, we review the criteria for appropriate diagnosis and molecular monitoring of NPM1-mutated AML.

SIGNIFICANCE

NPM1-mutated AML represents a distinct entity in the 2022 International Consensus Classification and 5th edition of World Health Organization classifications of myeloid neoplasms. The correct diagnosis of NPM1-mutated AML and its distinction from other AML entities is extremely important because it has clinical implications for the management of AML patients, such as genetic-based risk stratification according to 2022 ELN. Monitoring of MRD by qRT-PCR, combined with ELN risk stratification, can guide therapeutic decisions at the post-remission stage, e.g., whether or not to perform allogeneic hematopoietic stem cell transplantation.

Comparison of autologous, matched sibling, and alternative donor stem cell transplant outcomes for acute myeloid leukemia patients in first remission: A propensity score matching study

Autologous hematopoietic stem cell transplantation (auto-HSCT), matched sibling donor HSCT (MSD-HSCT), and alternative donor HSCT (AD-HSCT) are viable post-remission treatment options for acute myeloid leukemia (AML). A total of 283 de novo favorable- and intermediate-risk AML patients, based on the ELN 2022 criteria, in first complete remission were initially included for propensity score matching. Following the matching process, 126 patients were selected for further analysis, with 42 patients in each of the auto-HSCT, MSD-HSCT, and AD-HSCT groups. Among the AD-HSCT group, 38 of 42 (90.5%) patients received haploidentical HSCT. In patients with persistent undetectable measurable residual disease (uMRD) before transplant (n = 83), overall survival (OS) was similar across the groups. However, auto-HSCT showed a trend of increased disease-free survival (DFS) compared to AD-HSCT (HR 2.85, P = 0.09), resulting in a 3-year DFS and OS of 79.1% and 82.8%, respectively. In the non-persistent uMRD group (n = 38), auto-HSCT exhibited a tendency to increase the risk of relapse, particularly when compared to AD-HSCT (HR 0.24, P = 0.07), but this did not result in inferior OS. The monthly direct medical cost per patient within the first 2 years after HSCT was significantly lower in auto-HSCT compared to MSD-HSCT (P = 0.015) and AD-HSCT (P < 0.001). Our results provide evidence for the use of auto-HSCT as a viable therapeutic option for favorable- and intermediate-risk de novo AML patients in first complete remission with persistent uMRD. Additionally, our findings demonstrated a notable cost advantage associated with auto-HSCT compared to MSD-HSCT and AD-HSCT.

Venetoclax: A Game Changer in the Treatment of Younger AML Patients?

The combination approach based on venetoclax (VEN) with azacytidine (AZA) has significantly improved outcomes for elderly patients with acute myeloid leukemia (AML). This innovative approach has led to higher rates of overall response, measurable residual disease (MRD)-negative remissions, and overall survival compared with AZA monotherapy. As a result, this combination has emerged as the gold-standard treatment for elderly or unfit patients with AML who are not eligible for intensive therapy. In younger, fit patients with AML, intensive induction and consolidation chemotherapy is commonly used as a first-line approach; however, relapse continues to be the main reason for treatment failure in approximately 30-40% of patients. Efforts to improve MRD-negative response rates and to facilitate the transition to allogeneic hematopoietic stem cell transplantation, particularly in high-risk AML, have inspired trials exploring the combination of intensive chemotherapy with targeted agents. VEN, a first-in-class anti-BCL2 agent, combined with intensive chemotherapy regimens has shown deep MRD-negative remissions, producing prolonged event-free survival and enhancing the transition to allogeneic transplant in first-complete-remission patients. These benefits support the incremental advantages of adding VEN to intensive chemotherapy approaches across ELN risk subcategories, and provides a robust benchmark to design future trials. In this review, we will discuss current studies assessing the efficacy of frontline regimens integrating VEN into intensive chemotherapy in younger patients with AML and specific molecularly defined subgroups.

Understanding differential technologies for detection of MRD and how to incorporate into clinical practice

Patient- and leukemia-specific factors assessed at diagnosis classify patients with acute myeloid leukemia (AML) in risk categories that are prognostic for outcome. The induction phase with intensive chemotherapy in fit patients aims to reach a complete remission (CR) of less than 5% blasts in bone marrow by morphology. To deepen and sustain the response, induction is followed by consolidation treatment. This postremission treatment of patients with AML is graduated in intensity based on this favorable, intermediate, or adverse risk group classification as defined in the European Leukemia Network (ELN) 2022 recommendations. The increment of evidence that measurable residual disease (MRD) after induction can be superimposed on risk group at diagnosis is instrumental in tailoring further treatment accordingly. Several techniques are applied to detect MRD such as multiparameter flow cytometry (MFC), quantitative (digital) polymerase chain reaction (PCR), and next-generation sequencing. The clinical implementation of MRD and the technique used differ among institutes, leading to the accumulation of a wide range of data, and therefore harmonization is warranted. Currently, evidence for MRD guidance is limited to the time point after induction using MFC or quantitative PCR for NPM1 and core binding factor abnormalities in intermediate-risk patients. The role of MRD in targeted or nonintensive therapies needs to be clarified, although some data show improved survival in patients achieving CR-MRD negativity. Potential application of MRD for selection of conditioning before stem cell transplantation, monitoring after consolidation, and use as an intermediate end point in clinical trials need further evaluation.

Fatigue in newly diagnosed acute myeloid leukaemia: general population comparison and predictive factors

OBJECTIVES

This study compared the burden of fatigue between treatment-naïve patients with newly diagnosed acute myeloid leukaemia (AML) and the general population and investigated patient factors associated with fatigue severity.

METHODS

Pretreatment patient-reported fatigue was assessed with the Functional Assessment of Chronic Illness Therapy-Fatigue questionnaire in a sample of 463 newly diagnosed patients with AML who were enrolled in a clinical trial. Multivariable linear regression models were used to estimate the adjusted mean differences in fatigue between patients with AML and adults from the general population (n=847) by AML disease risk categories. A clinically meaningful difference in fatigue was defined as ≥3 points. Univariable and multivariable linear regression models were used to identify sociodemographic, clinical and molecular correlates of worse fatigue in patients with AML.

RESULTS

Patients with AML reported adjusted mean fatigue scores that were 7.5 points worse than the general population (95% CI -8.6 to -6.4, p<0.001). Across AML disease risk categories, adjusted mean differences in fatigue compared with the general population ranged from 6.7 points worse (patients with favourable risk: 95% CI -8.6 to -4.8, p<0.001) to 8.9 points worse (patients with poor risk, 95% CI -10.5 to -7.2, p<0.001). Overall, 91% of patients with AML reported fatigue that was equal to or worse than the general population's median fatigue score. Higher pretreatment fatigue was independently associated with female sex, WHO performance status ≥1 and lower platelet levels.

CONCLUSIONS

Patients with newly diagnosed AML reported worse fatigue than the general population, and mean differences exceeded twice the threshold for clinical significance. Our findings may help to identify patients with AML most likely to benefit from supportive care interventions to reduce fatigue.

Acute myeloid leukemia: challenges for diagnosis and treatment in Latin America

OBJECTIVE

to review the current diagnostic and therapeutic landscape of AML in Latin America as a reflection of other low- and middle-income countries and regions of the world. Encompassing both acute promyelocytic and non-promyelocytic disease types.

METHODS

We reviewed the literature and study registries concerning epidemiological features of patients with AML/APL treated in Latin America, as well as evaluated diagnostic and genetic stratification and patient fitness assessment challenges, the importance of early mortality and supportive care capacity, intensive and non-intensive chemotherapy alternatives, consolidation, and maintenance strategies including novel agents and hematopoietic stem cell transplantation.

RESULTS

Although most of the current technologies and treatment options are available in the region, a significant fraction of patients have only limited access to them. In addition, mortality in the first weeks from diagnosis is higher in the region compared to developed countries.

CONCLUSIONS

Disparities in access to technologies, supportive care capacity, and availability of novel agents and HSCT hinder results in our region, reflecting barriers common to other LMICs. Recent developments in the diagnosis and treatment of this disease must be implemented through education, collaborative clinical research, and advocacy to improve outcomes.

Autologous stem cell transplantation in adult patients with intermediate-risk acute myeloid leukemia in first complete remission and no detectable minimal residual disease. A comparative retrospective study with haploidentical transplants of the global committee and the ALWP of the EBMT

In patients with acute myeloid leukemia (AML) of intermediate-risk (IR) in first remission (CR1) with no measurable residual disease (MRD negative), the choice of the best consolidation is questionable. 1122 adult patients from 196 centers, transplanted in 2010-21 were analyzed: 547 received an autologous stem cell transplantation (ASCT) and 575 a Haploidentical donor transplant. Because of a significant interaction, comparisons were done separately for patients with wild-type FLT3 (FLT3-wt) and FLT3-ITD mutation (FLT3-ITD). In FLT3-wt patients, haploidentical transplants had two year lower relapse incidence (RI) (16.9% versus 32.6%; HR = 0.40, p < 0.001), higher NRM higher (17.2% vs 3.5%; HR = 7.02, p < 0.001), similar LFS (65.9% vs 63.8%; p = 0.37) and lower OS (73.2% vs 80.6%; HR = 1.69, p = 0.018). In FLT3-ITD patients, haploidentical transplants had two year lower RI (8.2% vs 47.8%; HR = 0.14, p < 0.001) higher NRM (20.2% vs 5.6%; HR = 3.43, p = 0.002), better LFS (71.5% vs 46.6%; HR = 0.53, p = 0.007) and similar OS (73.5% vs 61.9%; p = 0.44). In IR AML patients with FLT3-wt in MRD negative CR1, autologous stem cell transplantation is a valid option, while in patients with FLT3-ITD, haploidentical transplant is better. Whether autologous transplantation is superior to chemotherapy in FLT3-wt patients and the role of maintenance therapy with FLT3 inhibitors remain to be studied.

Standardization of Molecular MRD Levels in AML Using an Integral Vector Bearing ABL and the Mutation of Interest

Quantitative PCR for specific mutation is being increasingly used in Acute Myeloid Leukemia (AML) to assess Measurable Residual Disease (MRD), allowing for more tailored clinical decisions. To date, standardized molecular MRD is limited to typical NPM1 mutations and core binding factor translocations, with clear prognostic and clinical implications. The monitoring of other identified mutations lacks standardization, limiting its use and incorporation in clinical trials. To overcome this problem, we designed a plasmid bearing both the sequence of the mutation of interest and the ABL reference gene. This allows the use of commercial standards for ABL to determine the MRD response in copy number. We provide technical aspects of this approach as well as our experience with 19 patients with atypical NPM1, RUNX1 and IDH1/2 mutations. In all cases, we demonstrate a correlation between response and copy number. We further demonstrate how copy number monitoring can modulate the clinical management. Taken together, we provide proof of concept of a novel yet simple tool, which allows in-house MRD monitoring for identified mutations, with ABL-based commercial standards. This approach would facilitate large multi-center studies assessing the clinical relevance of selected MRD monitoring.

Analytical assay validation for acute myeloid leukemia measurable residual disease assessment by multiparametric flow cytometry

BACKGROUND

Measurable residual disease (MRD) assessed by multiparametric flow cytometry (MFC) has gained importance in clinical decision-making for acute myeloid leukemia (AML) patients. However, complying with the recent In Vitro Diagnostic Regulations (IVDR) in Europe and Food and Drug Administration (FDA) guidance in the United States requires rigorous validation prior to their use in investigational clinical trials and diagnostics. Validating AML MRD-MFC assays poses challenges due to the unique underlying disease biology and paucity of patient specimens. In this study, we describe an experimental framework for validation that meets regulatory expectations.

METHODS

Our validation efforts focused on evaluating assay accuracy, analytical specificity, analytical and functional sensitivity (limit of blank (LoB), detection (LLoD) and quantitation (LLoQ)), precision, linearity, sample/reagent stability and establishing the assay background frequencies.

RESULTS

Correlation between different MFC methods was highly significant (r = 0.99 for %blasts and r = 0.93 for %LAIPs). The analysis of LAIP specificity accurately discriminated from negative control cells. The assay demonstrated a LoB of 0.03, LLoD of 0.04, and LLoQ of 0.1%. Precision experiments yielded highly reproducible results (Coefficient of Variation <20%). Stability experiments demonstrated reliable measurement of samples up to 96 h from collection. Furthermore, the reference range of LAIP frequencies in non-AML patients was below 0.1%, ranging from 0.0% to 0.04%.

CONCLUSION

In this manuscript, we present the validation of an AML MFC-MRD assay using BM/PB patient specimens, adhering to best practices. Our approach is expected to assist other laboratories in expediting their validation activities to fulfill recent health authority guidelines.

Impact of different chemotherapy regimens on intestinal mucosal injury assessed with bedside ultrasound: a study in 213 AML patients

Introduction

Neutropenic enterocolitis (NEC) is a life-threatening complication reported in patients with acute myeloid leukemia (AML) following chemotherapy (CHT). Intensive induction and consolidation CHT may damage intestinal mucosa leading to a NEC episode (NECe). NEC reported mortality may be up to 30-60%. Early US-guided bed-side diagnosis and prompt treatment may substantially improve the survival. An emerging worldwide concern is the intestinal colonization by multi-drug-resistant bacteria especially when patients are exposed to chemotherapy regimens potentially correlated to mucosal damage.

Methods

In our study we prospectively enrolled all AML patients admitted in our leukemia unit to receive intensive induction and consolidation chemotherapy and experiencing chemotherapy-induced-neutropenia (CHTN).

Results and discussion

Overall, we enrolled N=213 patients from 2007 to March 2023. We recorded N=465 CHTN, and N=42 NECe (9.0% incidence). The aim of our study was to assess which chemotherapy regimens are more associated with NEC. We found that ALM1310, followed by 7 + 3 (daunorubicin), 7 + 3 (idarubicin), 5 + 3 + 3 (cytarabine, etoposide, idarubicin), and AML1310 (consolidation) were associated with a statistically higher incidence of NEC. We did not detect NEC episodes in patients treated with CPX-351, 5 + 2 (cytarabine, idarubicine), and high-dose cytarabine. Thus, we found that cytarabine could determine mucosal damage when associated with an anthracycline but not if delivered either alone or as dual-drug liposomal encapsulation of daunorubicin/cytarabine. We also describe NEC mortality, symptoms at diagnosis, intestinal sites involvement, and prognostic significance of bowel wall thickening.

A pilot study of cord blood-derived natural killer cells as maintenance therapy after autologous hematopoietic stem cell transplantation

Natural killer (NK) cell based immunotherapy is an emerging strategy in hematologic malignancies because allogeneic NK cells can provide potent antitumor immunity without inducing graft-versus-host disease. Thus, we expanded cord blood-derived NK (CB-NK) cells ex vivo from random (MHC mismatched and KIR mismatched) donors, and investigate the feasibility and efficacy of repeated infusions CB-NK cells as maintenance therapy after autologous hematopoietic stem cell transplantation (ASCT). Thirty-one patients with acute myeloid leukemia and high-risk lymphoma received ASCT and the adoptive CB-NK cell multiple infusions for maintenance therapy. Patients received a median dose of 5.98 × 107/kg (range, 1.87-17.69 × 107/kg) CB-NK cells and 23 patients completed four infusions, 8 patients received three infusions. Only mild infusion reactions occurred in 15.5% of 116 infusions. Compared to a contemporaneous cohort of 90 patients who did not receive NK cell therapy, the adoptive transfer of CB-NK cells as maintenance treatment showed a tendency of difference in decreasing the relapse rate between CB-NK group and control group (9.7% vs 24.4%). The patients who receiving NK cell infusions had a better PFS and OS than controls (4 year PFS, 84.4 ± 8.3% vs 73.5 ± 5.4%; and 4 year OS, 100% vs 78.1 ± 5.4%) . These findings demonstrate safety and validity of maintenance therapy using CB-NK cells multiple infusions after ASCT, and it is worthy of further clinical trial verification.

Measurable Residual Disease (MRD) by Flow Cytometry in Adult B-Acute Lymphoblastic Leukaemia (B-ALL) and Acute Myeloid Leukaemia (AML): Correlation with Molecular MRD Testing and Clinical Outcome at One Year

Measurable residual disease (MRD) detected by flow cytometry (FC) is well established in paediatric B- lymphoblastic leukaemia (B-ALL) and adult chronic lymphocytic leukaemia (CLL), but its utility in adult B-ALL and adult acute myeloid leukaemia (AML) is less clear. In this prospective MRD study, one of the largest in Australia to date, we examined consecutive bone marrow aspirates from adult participants with B-ALL (n = 47) and AML (n = 87) sent for FC-MRD testing at a quaternary referral hospital in Sydney. FC-MRD results were correlated to corresponding Mol-MRD testing where available and clinical outcomes at three-month intervals over 1 year. B-ALL showed a moderate positive correlation (rs = 0.401, p < 0.001), while there was no correlation between FC-MRD and Mol-MRD for AML (rs = 0.13, p = 0.237). Five FC-MRD patterns were identified which had significant associations with relapse (X2(4) = 31.17(4), p > 0.001) and survival (X2(4) = 13.67, p = 0.008) in AML, but not in B-ALL. The three-month MRD results were also strongly associated with survival in AML, while the association in B-ALL was less evident. There was a moderate correlation between FC-MRD and Mol-MRD in B-ALL but not AML. The association of FC-MRD with relapse and survival was stronger in AML than in B-ALL. Overall, these findings suggest divergent utilities of FC-MRD in AML and B-ALL.

What Influences the Decision to Proceed to Transplant for Patients With AML in First Remission?

Although allogeneic hematopoietic cell transplantation (allo-HCT) remains the backbone of curative treatment for the majority of fit adults diagnosed with AML, there is indeed a subset of patients for whom long-term remission may be achieved without transplantation. Remarkable changes in our knowledge of AML biology in recent years has transformed the landscape of diagnosis, management, and treatment of AML. Specifically, markedly increased understanding of molecular characteristics of AML, the expanded application of minimal/measurable residual diseases testing, and an increased armamentarium of leukemia-directed therapeutic agents have created a new paradigm for the medical care of patients with AML. An attempt is herein made to decipher the decision to proceed to transplant for patients with AML in first complete remission on the basis of the current best available evidence. The focus is on factors affecting the biology and treatment of AML itself, rather than on variables related to allo-HCT, an area characterized by significant advancements that have reduced overall therapy-related complications. This review seeks to focus on areas of particular complexity, while simultaneously providing clarity on how our current knowledge and treatment strategies may, or may not, influence the decision to pursue allo-HCT in patients with AML.

Trends in Outcome of Hematopoietic Stem Cell Transplantation: 5000 Transplantations and 30 Years of Single-Center Experience

In this single-center analysis, we evaluated the trends in 5185 hematopoietic cell transplantations performed between 1990 and 2022. The study group comprised 3237 allogeneic (alloHCT) and 1948 autologous (autoHCT) hematopoietic cell transplantations. In the multivariate analysis, there was an improvement in event-free-survival (EFS) after autoHCT (HR 0.6, 95% CI 0.4-0.7, p < 0.0001) due to reduced cumulative incidence of relapse in the last five years (56% in 2010-2014 vs. 38% in 2015-2022). An improvement in EFS after alloHCT over time was observed (HR 0.33, 95% CI 0.23-0.48, p < 0.0001), which was due to reduced non-relapse mortality. No difference in cumulative relapse incidence was observed over the last decade for allografted patients. Survival after autoHCT improved in Hodgkin's disease (HR 0.1, 95% CI 0.1-0.3), multiple myeloma (HR 0.4, 95% CI 0.2-0.7) and solid tumors (HR 0.2, 95% CI 0.2-0.4), while after alloHCT, improvement was observed in acute myeloid leukemia (HR 0.3, 95% CI 0.1-0.5), acute lymphoblastic leukemia (HR 0.2, 95% CI 0.1-0.5), Hodgkin's disease (HR 0.1, 95% CI 0.0-0.4), non-Hodgkin's lymphomas and chronic lymphocytic leukemia (HR 0.2, 95% CI 0.0-0.6), inborn diseases (HR 0.2, 95% CI 0.2-0.4) and acquired aplastic anemia with matched related donors and matched unrelated donors (HR 0.3, 95% CI 0.2-0.8).

NPM1-mutated acute myeloid leukemia: New pathogenetic and therapeutic insights and open questions

The nucleophosmin (NPM1) gene encodes for a multifunctional chaperone protein that is localized in the nucleolus but continuously shuttles between the nucleus and cytoplasm. NPM1 mutations occur in about one-third of AML, are AML-specific, usually involve exon 12 and are frequently associated with FLT3-ITD, DNMT3A, TET2, and IDH1/2 mutations. Because of its unique molecular and clinico-pathological features, NPM1-mutated AML is regarded as a distinct leukemia entity in both the International Consensus Classification (ICC) and the 5th edition of the World Health Organization (WHO) classification of myeloid neoplasms. All NPM1 mutations generate leukemic mutants that are aberrantly exported in the cytoplasm of the leukemic cells and are relevant to the pathogenesis of the disease. Here, we focus on recently identified functions of the NPM1 mutant at chromatin level and its relevance in driving HOX/MEIS gene expression. We also discuss yet controversial issues of the ICC/WHO classifications, including the biological and clinical significance of therapy-related NPM1-mutated AML and the relevance of blasts percentage in defining NPM1-mutated AML. Finally, we address the impact of new targeted therapies in NPM1-mutated AML with focus on CAR T cells directed against NPM1/HLA neoepitopes, as well as XPO1 and menin inhibitors.

LSC17 score complements genetics and measurable residual disease in acute myeloid leukemia: an ALFA study

Whether the LSC17 gene expression can improve risk stratification in the context of next generation sequencing-based risk stratification and measurable residual disease (MRD) in patients with intensively treated AML has not been explored. We analyzed LSC17 in 504 adult patients prospectively treated in the ALFA-0702 trial. RUNX1 or TP53 mutations were associated with higher LSC1 scores while CEBPA and NPM1 mutations were associated with lower scores. Patients with high LSC17 scores had a lower rate of complete response (CR) in a multivariable analysis (odds ratio, 0.41; P = .0007), accounting for European LeukemiaNet 2022 (ELN22), age, and white blood cell count (WBC). LSC17-high status was associated with shorter overall survival (OS) (3-year OS: 70.0% vs 52.7% in patients with LSC17-low status; P < .0001). In a multivariable analysis considering ELN22, age, and WBC, patients with LSC17-high status had shorter disease-free survival (DFS) (hazard ratio [HR], 1.36; P = .048) than those with LSC17-low status. In 123 patients with NPM1-mutated AML in CR, LSC17-high status predicted poorer DFS (HR, 2.34; P = .01), independent of age, WBC, ELN22 risk, and NPM1-MRD. LSC-low status and negative NPM1-MRD identified a subset comprising 48% of patients with mutated NPM1 with a 3-year OS from CR of 93.1% compared with 60.7% in those with LSC17-high status and/or positive NPM1-MRD (P = .0001). Overall, LSC17 assessment refines genetic risk stratification in adult patients with AML treated intensively. Combined with MRD, LSC17 identifies a subset of patients with NPM1-mutated AML with excellent clinical outcome.

Measurable residual disease in patients undergoing allogeneic transplant for acute myeloid leukemia

The most common indication for allogeneic hematopoietic cell transplant (alloHCT) is maintenance of remission after initial treatment for patients with acute myeloid leukemia (AML). Loss of remission, relapse, remains however the most frequent cause of alloHCT failure. There is strong evidence that detectable persistent disease burden ("measurable residual disease", MRD) in patients with AML in remission prior to alloHCT is associated with increased risk of post-transplant relapse. MRD status as a summative assessment of response to pre-transplant therapy may allow superior patient-personalized risk stratification compared with models solely incorporating pre-treatment variables. An optimal methodology for AML MRD detection has not yet been established, but molecular methods such as DNA-sequencing may have additional prognostic utility compared to current approaches. There is growing evidence that intervention on AML MRD positivity may improve post-transplant outcomes. New initiatives will generate actionable data on the clinical utility of AML MRD testing for patients undergoing alloHCT.

Using Measurable Residual Disease to Optimize Management of AML, ALL, and Chronic Myeloid Leukemia

In this review, we discuss the use of measurable residual disease (MRD) in AML, ALL, and chronic myeloid leukemia (CML). Our aims were to review the different methodologies for MRD assessment; describe the clinical relevance and medical decision making on the basis of MRD; compare and contrast the usage of MRD across AML, ALL, and CML; and discuss what patients need to know about MRD as it relates to their disease status and treatment. Finally, we discuss ongoing challenges and future directions with the goal of optimizing MRD usage in leukemia management.

Acute Myeloid Leukemia Stem Cells in Minimal/Measurable Residual Disease Detection

Acute myeloid leukemia (AML) is a hematological malignancy characterized by an abundance of incompletely matured or immature clonally derived hematopoietic precursors called leukemic blasts. Rare leukemia stem cells (LSCs) that can self-renew as well as give rise to leukemic progenitors comprising the bulk of leukemic blasts are considered the cellular reservoir of disease initiation and maintenance. LSCs are widely thought to be relatively resistant as well as adaptive to chemotherapy and can cause disease relapse. Therefore, it is imperative to understand the molecular bases of LSC forms and functions during different stages of disease progression, so we can more accurately identify these cells and design therapies to target them. Irrespective of the morphological, cytogenetic, and cellular heterogeneity of AML, the uniform, singularly important and independently significant prognosticator of disease response to therapy and patient outcome is measurable or minimal residual disease (MRD) detection, defined by residual disease detection below the morphology-based 5% blast threshold. The importance of LSC identification and frequency estimation during MRD detection, in order to make MRD more effective in predicting disease relapse and modifying therapeutic regimen is becoming increasingly apparent. This review focuses on summarizing functional and cellular composition-based LSC identification and linking those studies to current techniques of MRD detection to suggest LSC-inclusive MRD detection as well as outline outstanding questions that need to be addressed to improve the future of AML clinical management and treatment outcomes.

Impact of gemtuzumab ozogamicin consolidation on hematopoietic stem cells (HSCs) mobilization in AML: analysis of 20 patients

Gemtuzumab ozogamicin (GO), is an anti-CD33 monoclonal antibody, approved for AML CD33 + , those patients with low and intermediate-risk who obtain a complete response may also be candidated for consolidation with autologous stem cell transplantation (ASCT). However, there are scant data on the mobilization of hemopoietic stem cells (HSC) after fractionated GO. We retrospectively studied data from five Italian centers and identified 20 patients (median age 54 years, range 29-69, 15 female, 15 NPM1^mutated) that attempted HSC mobilization after fractionated doses of GO + "7 + 3" regimen and 1-2 cycles of consolidation (GO + HDAC + daunorubicin). After chemotherapy and standard G-CSF, 11/20 patients (55%) reached the threshold of 20 CD34 + /µL, and HSC were successfully harvested, while 9 patients (45%) failed. The median day of apheresis was Day + 26 from the start of chemotherapy (range 22-39 days). In good mobilizer patients, the median circulating CD34 + cells were 35.9 cells/µL and the median CD34 + harvested were 4.65 × 10⁶/kg of patients' body weight. With a median follow-up of 12.7 months, at 24 months from the first diagnosis, 93.3% of all 20 patients were alive and the median overall survival was 25 months. The 2-year RFS rate from the timepoint of the first CR was 72.6%, while the median RFS was not reached. However, only five patients underwent ASCT and achieved full engraftment.In conclusion, in our cohort of patients, the addition of GO reduced HSC mobilization and harvesting, which was reached in about 55% of patients. Nevertheless, further studies are warranted to evaluate the effects of fractionated doses of GO on HSC mobilization and ASCT outcomes.

Measurable residual disease in adult acute myeloid leukaemia: evaluation of a multidimensional 'radar' flow cytometric plot analysis method

Measurable residual disease (MRD) monitoring in acute myeloid leukaemia (AML) is becoming increasingly important and is predominantly performed by multiparameter flow cytometry (MFC) or quantitative polymerase chain reactions (RT-qPCR). We investigated the use of multidimensional plots (MD-MFC) for AML MRD monitoring in an adult cohort. AML MRD was determined using a novel MD-MFC method for 115 MRD samples. Results were correlated with traditional two-dimensional MFC (2D-MFC) and molecular methods. Using the standard cut-off of 0.1% CD45+ cells, concordance was 99/115 (p=0.332). Eighty-four of 115 were concordant using a very low reporting limit of 0.01% (p=0.216). MRD <0.1% by either method was present in 40 of 115 samples. Fifteen of 40 were MD-MFC positive and 2D-MFC negative. Of these two of 15 had a molecular MRD marker and both were positive. Molecular MRD markers were available in 36 of 115 cases. Twenty-one of 36 (58%) were concordant with MD-MFC. Eight of 36 had detectable molecular MRD only and eight of 36 had positive MD-MFC only. There was no correlation between either the MFC method and the molecular results. In summary, there is good correlation between MD- and 2D-MFC-MRD and no correlation between the MFC and molecular methods.

Prognostic Value of Measurable Residual Disease in Patients with AML Undergoing HSCT: A Multicenter Study

Allogeneic hematopoietic stem cell transplantation (HSCT) represents the best therapeutic option for many patients with acute myeloid leukemia (AML). However, relapse remains the main cause of mortality after transplantation. The detection of measurable residual disease (MRD) by multiparameter flow cytometry (MFC) in AML, before and after HSCT, has been described as a powerful predictor of outcome. Nevertheless, multicenter and standardized studies are lacking. A retrospective analysis was performed, including 295 AML patients undergoing HSCT in 4 centers that worked according to recommendations from the Euroflow consortium. Among patients in complete remission (CR), MRD levels prior to transplantation significantly influenced outcomes, with overall (OS) and leukemia free survival (LFS) at 2 years of 76.7% and 67.6% for MRD-negative patients, 68.5% and 49.7% for MRD-low patients (MRD < 0.1), and 50.5% and 36.6% for MRD-high patients (MRD ≥ 0.1) (p < 0.001), respectively. MRD level did influence the outcome, irrespective of the conditioning regimen. In our patient cohort, positive MRD on day +100 after transplantation was associated with an extremely poor prognosis, with a cumulative incidence of relapse of 93.3%. In conclusion, our multicenter study confirms the prognostic value of MRD performed in accordance with standardized recommendations.

Idarubicin plus BuCy versus BuCy conditioning regimens for intermediate-risk acute myeloid leukemia in first complete remission undergoing auto-HSCT: An open-label, multicenter, randomized phase 3 trial

We report a randomized prospective phase 3 study, designed to evaluate the efficacy and tolerability of idarubicin plus busulfan and cyclophosphamide (IDA-BuCy) versus BuCy in autologous hematopoietic stem-cell transplantation (auto-HSCT) for intermediate-risk acute myeloid leukemia (IR-AML) patients in first complete remission (CR1). One hundred and fifty-four patients were enrolled and randomized to receive IDA-BuCy (IDA 15 mg/m2/day on days -12 to -10, Bu 3.2 mg/kg/day on days -7 to -4, and Cy 60 mg/kg/day on days -3 to -2) or BuCy. The 2-year incidence of relapse was 15.6% and 19.5% in IDA-BuCy and BuCy groups (p = 0.482), respectively. There was no significant overall survival (OS) and disease-free survival (DFS) benefit for IR-AML patients receiving IDA-BuCy (2-year OS 81.8% in IDA-BuCy vs. 83.1% in BuCy, p = 0.798; 2-year DFS 76.6% in IDA-BuCy vs. 79.2% in BuCy, p = 0.693). Grade 3 or worse regimen-related toxicity (RRT) was reported for 22 (28.9%) of 76 and 9 (12.0%) of 75 patients in two groups (p = 0.015), respectively. AEs within 100 days with an outcome of death were reported for 4 (5.3%) and 0 patients in two groups. In conclusion, IDA-BuCy has higher RRT and similar anti-leukemic activity compared with BuCy in IR-AML patients in CR1 undergoing auto-HSCT. Thus, caution should be taken when choosing IDA-BuCy for IR-AML patients in CR1 with auto-HSCT. This trial is registered with ClinicalTrials.gov, NCT02671708, and is complete.

Is it the time to integrate novel sequencing technologies into clinical practice?

PURPOSE OF REVIEW

The aim of this study was to provide insight into how novel next-generation sequencing (NGS) techniques are set to revolutionize clinical practice.

RECENT FINDINGS

Advances in sequencing technologies have focused on improved capture of mutations and reads and cellular resolution. Both short and long read DNA sequencing technology are being refined and combined in novel ways with other multiomic approaches to gain unprecedented biological insight into disease. Single-cell (sc)DNA-seq and integrated scDNA-seq with immunophenotyping provide granular information on disease composition such as clonal hierarchy, co-mutation status, zygosity, clonal diversity and genotype phenotype correlations. These and other techniques can identify rare cell populations providing the opportunity for increased sensitivity in measurable residual disease monitoring and precise characterization of residual clones permitting distinction of leukemic from pre/nonmalignant clones.

SUMMARY

Increasing genetics-based mechanistic insights and classification of myeloid diseases along with a decrease in the cost of high-throughput NGS mean novel sequencing technologies are closer to being a reality in standard clinical practice. These technologies are poised to improve diagnostics, our ability to monitor treatment response and minimal residual disease and allow the study of premalignant conditions such as clonal haematopoiesis.

Prediction of Nonrelapse Mortality in Patients With Acute Myeloid Leukemia and Acute Lymphoblastic Leukemia Receiving Allogeneic Stem Cell Transplantation With Posttransplantation Cyclophosphamide-based Graft Versus Host Disease Prophylaxis

Graft versus host disease (GVHD) prophylaxis with posttransplantation cyclophosphamide (PTCY) has been established to reduce severe GVHD, and thereby potentially reducing nonrelapse mortality (NRM) after allogeneic stem cell transplantation (alloSCT). We evaluated the predictive capacity of established NRM-risk scores in patients receiving PTCY-based GVHD prophylaxis, and subsequently developed and validated a novel PTCY-specific NRM-risk model. Adult patients (n = 1861) with AML or ALL in first complete remission who received alloSCT with PTCY-based GVHD prophylaxis were included. The PTCY-risk score was developed using multivariable Fine and Gray regression, selecting parameters from the hematopoietic cell transplantation-comorbidity index (HCT-CI) and European Group for Blood and Marrow Transplantation (EBMT) score with a subdistribution hazard ratio (SHR) of ≥1.2 for 2-year NRM in the training set (70% split), which was validated in the test set (30%). The performance of the EBMT score, HCT-CI, and integrated EBMT score was relatively poor for discriminating 2-year NRM (c-statistic 51.7%, 56.6%, and 59.2%, respectively). The PTCY-risk score included 10 variables which were collapsed in 3 risk groups estimating 2-year NRM of 11% ± 2%, 19% ± 2%, and 36% ± 3% (training set, c-statistic 64%), and 11% ± 2%, 18% ± 3%, and 31% ± 5% (test set, c-statistic 63%), which also translated into different overall survival. Collectively, we developed an NRM-risk score for acute leukemia patients receiving PTCY that better predicted 2-year NRM compared with existing models, which might be applicable to the specific toxicities of high-dose cyclophosphamide.

Measurable Residual Disease (MRD) as a Surrogate Efficacy-Response Biomarker in AML

In acute myeloid leukemia (AML) many patients experience relapse, despite the achievement of morphological complete remission; therefore, conventional morphologic criteria are currently considered inadequate for assessing the quality of the response after treatment. Quantification of measurable residual disease (MRD) has been established as a strong prognostic marker in AML and patients that test MRD negative have lower relapse rates and better survival than those who test positive. Different techniques, varying in their sensitivity and applicability to patients, are available for the measurement of MRD and their use as a guide for selecting the most optimal post-remission therapy is an area of active investigation. Although still controversial, MRD prognostic value promises to support drug development serving as a surrogate biomarker, potentially useful for accelerating the regulatory approval of new agents. In this review, we will critically examine the methods used to detect MRD and its potential role as a study endpoint.