Dismal outcome of refractory or relapsing patients with myelodysplasia-related acute myeloid leukemia partially alleviated by intensive chemotherapy

BACKGROUND

Acute myeloid leukemia (AML) with myelodysplasia-related characteristics is a heterogeneous subset of AML that has been challenged throughout the history of myeloid malignancies classifications, considered to have similar outcomes as intermediate- or adverse-risk AML depending on the subgroup. However, little is known about the fate of these patients in refractory or relapsed situation (R/R) after first line therapy.

METHODS

A large series of R/R AML patients, recorded in the French DATAML registry, have received either intensive chemotherapy (ICT), azacitidine (AZA) as single agent, or best supportive care (BSC). A cohort of 183 patients (median age 63-year-old) with what was called at the time AML-MRC has been explored, and data are reported here.

RESULTS

Patient status was refractory for 93, while 90 had relapsed. Respectively, 88, 34, and 61 were included in the three treatment arms. The median OS of the whole cohort was 4.2 months (95%CI: 3.1-5.6) with a mean 1-year overall survival of 24% ± 3.2%. There was no significant survival difference between refractory and relapsed patients. The BSC group had overall a significantly worse outcome (p = 0.0001), and this remained true in both refractory (p = 0.01) and relapsed (p = 0.002) patients. Similar survivals were observed in both groups comparing ICT and AZA.

CONCLUSIONS

These data, reporting about an ill-explored population, indicate the poor prognosis of this condition where both ICT and AZA can be proposed. The latter, which was demonstrated here to be a feasible option, should be added to new targeted therapies.

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.

Artificial intelligence-based prediction models for acute myeloid leukemia using real-life data: A DATAML registry study

We designed artificial intelligence-based prediction models (AIPM) using 52 diagnostic variables from 3687 patients included in the DATAML registry treated with intensive chemotherapy (IC, N = 3030) or azacitidine (AZA, N = 657) for an acute myeloid leukemia (AML). A neural network called multilayer perceptron (MLP) achieved a prediction accuracy for overall survival (OS) of 68.5% and 62.1% in the IC and AZA cohorts, respectively. The Boruta algorithm could select the most important variables for prediction without decreasing accuracy. Thirteen features were retained with this algorithm in the IC cohort: age, cytogenetic risk, white blood cells count, LDH, platelet count, albumin, MPO expression, mean corpuscular volume, CD117 expression, NPM1 mutation, AML status (de novo or secondary), multilineage dysplasia and ASXL1 mutation; and 7 variables in the AZA cohort: blood blasts, serum ferritin, CD56, LDH, hemoglobin, CD13 and disseminated intravascular coagulation (DIC). We believe that AIPM could help hematologists to deal with the huge amount of data available at diagnosis, enabling them to have an OS estimation and guide their treatment choice. Our registry-based AIPM could offer a large real-life dataset with original and exhaustive features and select a low number of diagnostic features with an equivalent accuracy of prediction, more appropriate to routine practice.

Principal component analysis yields results comparable to those of an elaborate Boolean strategy: simplifying the assessment of measurable residual disease in chronic lymphocytic leukemia patients

INTRODUCTION

Measurable residual disease (MRD) is becoming increasingly important in the chronic lymphocytic leukemia (CLL) context. It is of independent prognostic significance in terms of favorable progression-free and overall survival. The standardized methods used to assess CLL MRD are based on flow cytometry and real-time quantitative PCR. We here present a nine-color assay for CLL MRD with the ROR-1 marker antigen as recommended by the European Research Initiative (ERIC) on CLL; the sensitivity is at least 10-5.

MATERIALS AND METHODS

We used 54 samples to develop a new principal component analysis (PCA) method based on the Kaluza© "radar" presentation mode. We used a Navios flow cytometer (Beckman Coulter©).

RESULTS

We confirmed the linearity of our method over more than five dilutions. The specificity limit was 1.3×10-6 and the lower limit of detection was 3.6×10-6. Compared to the Boolean method, the sensitivity, specificity, and positive and negative predictive values of our PCA method were 100%. When MRD was detectable, PCA and Boolean assays were in agreement (linear regression, R2 = 0.99).

CONCLUSION

We developed a new PCA-based method for detection of CLL MRD. Our method is comparable to that of the consensus method in terms of sensitivity, and it is also much easier and faster.

The presence of a chromosomal abnormality in cytopenia without dysplasia identifies a category of high-risk clonal cytopenia of unknown significance

Myelodysplastic syndromes (MDS) are hematological malignancies classically defined by the presence of cytopenia(s) and dysmorphic myeloid cells. It is now known that MDS can be preceded by a pre-malignant condition called clonal cytopenia of unknown significance (CCUS), which associates a clonality marker with cytopenia in the absence of criteria of dysplasia. However, to date, it is not clear whether chromosomal abnormalities should be considered in the definition of CCUS or if they carry a prognostic impact in CCUS patients. In this study, we analyzed the clinico-biological features and outcomes of 34 patients who presented with one or more cytopenias, an absence of significant dysplasia, and a presence of a chromosomal abnormality (CA). We named this entity chromosomal abnormality with cytopenia of undetermined significance (CACtUS). We show that these patients are slightly older than MDS patients and that they more frequently presented with normocytic anemia. Most CACtUS patients exhibited only one unbalanced CA. The number and type of mutations were comparable between CACtUS patients and MDS patients. Regardless of the cytogenetic abnormality, the clinicobiological characteristics, overall survival, and risk of progression to high-risk (HR) MDS were similar between CACtUS patients and low-risk MDS patients. Thus, we suggest that CACtUS patients can be considered as HR-CCUS and should receive the follow-up regimen recommended for MDS patients.

Prognostic Impact of Unsupervised Early Assessment of Bulk and Leukemic Stem Cell Measurable Residual Disease in Acute Myeloid Leukemia

PURPOSE

Acute myeloid leukemias (AML) are clonal diseases that develop from leukemic stem cells (LSC) that carry an independent prognostic impact on the initial response to induction chemotherapy, demonstrating the clinical relevance of LSC abundance in AML. In 2018, the European LeukemiaNet published recommendations for the detection of measurable residual disease (Bulk MRD) and suggested the exploration of LSC MRD and the use of multiparametric displays.

EXPERIMENTAL DESIGN

We evaluated the performance of unsupervised clustering for the post-induction assessment of bulk and LSC MRD in 155 patients with AML who received intensive conventional chemotherapy treatment.

RESULTS

The median overall survival (OS) for Bulk+ MRD patients was 16.7 months and was not reached for negative patients (HR, 3.82; P < 0.0001). The median OS of LSC+ MRD patients was 25.0 months and not reached for negative patients (HR, 2.84; P = 0.001). Interestingly, 1-year (y) and 3-y OS were 60% and 39% in Bulk+, 91% and 52% in Bulk-LSC+ and 92% and 88% in Bulk-LSC-.

CONCLUSIONS

In this study, we confirm the prognostic impact of post-induction multiparametric flow cytometry Bulk MRD in patients with AML. Focusing on LSCs, we identified a group of patients with negative Bulk MRD but positive LSC MRD (25.8% of our cohort) with an intermediate prognosis, demonstrating the interest of MRD analysis focusing on leukemic chemoresistant subpopulations.

Phenotypically-defined stages of leukemia arrest predict main driver mutations subgroups, and outcome in acute myeloid leukemia

Classifications of acute myeloid leukemia (AML) patients rely on morphologic, cytogenetic, and molecular features. Here we have established a novel flow cytometry-based immunophenotypic stratification showing that AML blasts are blocked at specific stages of differentiation where features of normal myelopoiesis are preserved. Six stages of leukemia differentiation-arrest categories based on CD34, CD117, CD13, CD33, MPO, and HLA-DR expression were identified in two independent cohorts of 2087 and 1209 AML patients. Hematopoietic stem cell/multipotent progenitor-like AMLs display low proliferation rate, inv(3) or RUNX1 mutations, and high leukemic stem cell frequency as well as poor outcome, whereas granulocyte-monocyte progenitor-like AMLs have CEBPA mutations, RUNX1-RUNX1T1 or CBFB-MYH11 translocations, lower leukemic stem cell frequency, higher chemosensitivity, and better outcome. NPM1 mutations correlate with most mature stages of leukemia arrest together with TET2 or IDH mutations in granulocyte progenitors-like AML or with DNMT3A mutations in monocyte progenitors-like AML. Overall, we demonstrate that AML is arrested at specific stages of myeloid differentiation (SLA classification) that significantly correlate with AML genetic lesions, clinical presentation, stem cell properties, chemosensitivity, response to therapy, and outcome.

Unsupervised Flow Cytometry Analysis Allows for an Accurate Identification of Minimal Residual Disease Assessment in Acute Myeloid Leukemia

The assessment of minimal residual disease (MRD) is increasingly considered to monitor response to therapy in hematological malignancies. In acute myeloblastic leukemia (AML), molecular MRD (mMRD) is possible for about half the patients while multiparameter flow cytometry (MFC) is more broadly available. However, MFC analysis strategies are highly operator-dependent. Recently, new tools have been designed for unsupervised MFC analysis, segregating cell-clusters with the same immunophenotypic characteristics. Here, the Flow-Self-Organizing-Maps (FlowSOM) tool was applied to assess MFC-MRD in 96 bone marrow (BM) follow-up (FU) time-points from 40 AML patients with available mMRD. A reference FlowSOM display was built from 19 healthy/normal BM samples (NBM), then simultaneously compared to the patient's diagnosis and FU samples at each time-point. MRD clusters were characterized individually in terms of cell numbers and immunophenotype. This strategy disclosed subclones with varying immunophenotype within single diagnosis and FU samples including populations absent from NBM. Detectable MRD was as low as 0.09% in MFC and 0.051% for mMRD. The concordance between mMRD and MFC-MRD was 80.2%. MFC yielded 85% specificity and 69% sensitivity compared to mMRD. Unsupervised MFC is shown here to allow for an easy and robust assessment of MRD, applicable also to AML patients without molecular markers.

Real-World Outcomes of Patients with Refractory or Relapsed FLT3-ITD Acute Myeloid Leukemia: A Toulouse-Bordeaux DATAML Registry Study

Two recent phase 3 trials showed that outcomes for relapsed/refractory (R/R) FLT3-mutated acute myeloid leukemia (AML) patients may be improved by a single-agent tyrosine kinase inhibitor (TKI) (i.e., quizartinib or gilteritinib). In the current study, we retrospectively investigated the characteristics and real-world outcomes of R/R FLT3-internal tandem duplication (ITD) acute myeloid leukemia (AML) patients in the Toulouse-Bordeaux DATAML registry. In the study, we included 316 patients with FLT3-ITD AML that received intensive chemotherapy as a first-line treatment. The rate of complete remission (CR) or CR without hematological recovery (CRi) was 75.2%, and 160 patients were R/R after a first-line TKI-free treatment (n = 294). Within the subgroup of R/R patients that fulfilled the main criteria of the QUANTUM-R study, 48.9% received an intensive salvage regimen; none received hypomethylating agents or low-dose cytarabine. Among the R/R FLT3-ITD AML patients with CR1 durations < 6 months who received intensive TKI-free treatment, the rate of CR or CRi after salvage chemotherapy was 52.8%, and these results allowed a bridge to be transplanted in 39.6% of cases. Finally, in this QUANTUM-R standard arm-matched cohort, the median overall survival (OS) was 7.0 months and 1-, 3- and 5-year OS were 30.2%, 23.7% and 21.4%, respectively. To conclude, these real-world data show that the intensity of the second-line treatment likely affects response and transplantation rates. Furthermore, the results indicate that including patients with low-intensity regimens, such as low-dose cytarabine or hypomethylating agents, in the control arm of a phase 3 trial may be counterproductive and could compromise the results of the study.

An R-Derived FlowSOM Process to Analyze Unsupervised Clustering of Normal and Malignant Human Bone Marrow Classical Flow Cytometry Data

Multiparameter flow cytometry (MFC) is a powerful and versatile tool to accurately analyze cell subsets, notably to explore normal and pathological hematopoiesis. Yet, mostly supervised subjective strategies are used to identify cell subsets in this complex tissue. In the past few years, the implementation of mass cytometry and the big data generated have led to a blossoming of new software solutions. Their application to classical MFC in hematology is however still seldom reported. Here, we show how one of these new tools, the FlowSOM R solution, can be applied, together with the Kaluza® software, to a new delineation of hematopoietic subsets in normal human bone marrow (BM). We thus combined the unsupervised discrimination of cell subsets provided by FlowSOM and their expert-driven node-by-node assignment to known or new hematopoietic subsets. We also show how this new tool could modify the MFC exploration of hematological malignancies both at diagnosis (Dg) and follow-up (FU). This can be achieved by direct comparison of merged listmodes of reference normal BM, Dg, and FU samples of a representative acute myeloblastic case tested with the same immunophenotyping panel. This provides an immediate unsupervised evaluation of minimal residual disease. © 2019 International Society for Advancement of Cytometry.

Reference Values for WBC Differential by Hematoflow Analysis

Objectives

WBC differentials performed using flow cytometry with monoclonal antibodies have been developed in the last decade and are nowadays integrated into the routine workflow of some laboratories. Definition of reference values for each population is required in order to achieve an automatic validation of the results by laboratory software.

Methods

We analyzed 584 samples from three hospitals using the Hematoflow solution to define the reference values.

Results

Reference values are presented for five groups according to age (0-5, 6-11, 12-19, 20-69, and >69 years).

Conclusions

These normal values will be helpful in the definition of relevant threshold for the automatic validation of samples analyzed by flow cytometry and the flagging of pathologic samples.