Prognostic significance of flow cytometric minimal residual disease assessment after the first induction course in Chinese childhood acute myeloid leukemia

Association of hematologic response and assay sensitivity on the prognostic impact of measurable residual disease in acute myeloid leukemia: a systematic review and meta-analysis

Measurable residual disease (MRD) is associated with relapse and survival in acute myeloid leukemia (AML). We aimed to quantify the impact of MRD on outcomes across clinical contexts, including its association with hematologic response and MRD assay sensitivity. We performed systematic literature review and meta-analysis of 48 studies that reported the association between MRD and overall survival (OS) or disease-free survival (DFS) in AML and provided information on the MRD threshold used and the hematologic response of the study population. Among studies limited to patients in complete remission (CR), the estimated 5-year OS for the MRD-negative and MRD-positive groups was 67% (95% Bayesian credible interval [CrI], 53-77%) and 31% (95% CrI, 18-44%), respectively. Achievement of an MRD-negative response was associated with superior DFS and OS, regardless of MRD threshold or analytic sensitivity. Among patients in CR, the benefit of MRD negativity was highest in studies using an MRD cutoff less than 0.1%. The beneficial impact of MRD negativity was observed across MRD assays and timing of MRD assessment. In patients with AML in morphological remission, achievement of MRD negativity is associated with superior DFS and OS, irrespective of hematologic response or the MRD threshold used.

Predictive impact of residual disease detected using multiparametric flow cytometry on risk stratification of paediatric acute myeloid leukaemia with normal karyotype

INTRODUCTION

Residual disease (RD) detected using multiparametric flow cytometry (MFC) is an independent predictive variable of relapse in acute myeloid leukaemia (AML). However, RD thresholds and optimal assessment time points remain to be validated.

MATERIAL AND METHODS

We investigated the significance of RD after induction therapy in paediatric AML with normal karyotype between June 2008 and June 2018. Bone marrow samples from 73 patients were collected at the end of the first (BMA-1) and second (BMA-2) induction courses to monitor RD using MFC.

RESULTS

Presence of RD after BMA-1 and/or BMA-2 correlated with poor relapse-free (RFS) and overall survival at 0.1% RD cutoff level. Receiver operating characteristic curve showed that RD cutoff levels of 1.3% and 0.5% after BMA-1 and BMA-2, respectively, predicted events with the highest sensitivity and specificity. In multivariable analysis, RD after BMA-2 was the strongest independent risk predictor for poor RFS (hazard ratio 2.934; 95% confidence interval: 1.106-7.782; P = .031).

CONCLUSIONS

Our study therefore suggests that an RD level ≥0.5% after BMA-2 has a significant predictive impact on the prognosis of AML patients having normal karyotype and thus guide the stratification of treatment strategies.

Association of Measurable Residual Disease With Survival Outcomes in Patients With Acute Myeloid Leukemia: A Systematic Review and Meta-analysis

IMPORTANCE

Measurable residual disease (MRD) refers to neoplastic cells that cannot be detected by standard cytomorphologic analysis. In patients with acute myeloid leukemia (AML), determining the association of MRD with survival may improve prognostication and inform selection of efficient clinical trial end points.

OBJECTIVE

To examine the association between MRD status and disease-free survival (DFS) and overall survival (OS) in patients with AML using scientific literature.

DATA SOURCES

Clinical studies on AML published between January 1, 2000, and October 1, 2018, were identified via searches of PubMed, Embase, and MEDLINE.

STUDY SELECTION

Literature search and study screening were performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Studies that assessed DFS or OS by MRD status in patients with AML were included. Reviews, non-English-language articles, and studies reporting only outcomes after hematopoietic cell transplantation or those with insufficient description of MRD information were excluded.

DATA EXTRACTION AND SYNTHESIS

Study sample size, median patient age, median follow-up time, MRD detection method, MRD assessment time points, AML subtype, specimen source, and survival outcomes were extracted. Meta-analyses were performed separately for DFS and OS using bayesian hierarchical modeling.

MAIN OUTCOMES AND MEASURES

Meta-analyses of survival probabilities and hazard ratios (HRs) were conducted for OS and DFS according to MRD status.

RESULTS

Eighty-one publications reporting on 11 151 patients were included. The average HR for achieving MRD negativity was 0.36 (95% bayesian credible interval [CrI], 0.33-0.39) for OS and 0.37 (95% CrI, 0.34-0.40) for DFS. The estimated 5-year DFS was 64% for patients without MRD and 25% for those with MRD, and the estimated OS was 68% for patients without MRD and 34% for those with MRD. The association of MRD negativity with DFS and OS was significant for all subgroups, with the exception of MRD assessed by cytogenetics or fluorescent in situ hybridization.

CONCLUSIONS AND RELEVANCE

The findings of this meta-analysis suggest that achievement of MRD negativity is associated with superior DFS and OS in patients with AML. The value of MRD negativity appears to be consistent across age groups, AML subtypes, time of MRD assessment, specimen source, and MRD detection methods. These results support MRD status as an end point that may allow for accelerated evaluation of novel therapies in AML.

Automated analysis of acute myeloid leukemia minimal residual disease using a support vector machine

We investigated the ability of support vector machines (SVM) to analyze minimal residual disease (MRD) in flow cytometry data from patients with acute myeloid leukemia (AML) automatically, objectively and standardly. The initial disease data and MRD review data in the form of 159 flow cytometry standard 3.0 files from 36 CD7-positive AML patients in whom MRD was detected more than once were exported. SVM was used for training with setting the initial disease data to 1 as the flag and setting 15 healthy persons to set 0 as the flag. Based on the two training groups, parameters were optimized, and a predictive model was built to analyze MRD data from each patient. The automated analysis results from the SVM model were compared to those obtained through conventional analysis to determine reliability. Automated analysis results based on the model did not differ from and were correlated with results obtained through conventional analysis (correlation coefficient c = 0.986, P > 0.05). Thus the SVM model could potentially be used to analyze flow cytometry-based AML MRD data automatically, objectively, and in a standardized manner.

A critical review of which children with acute myeloid leukaemia need stem cell procedures

The last decades have seen parallel improvements in chemotherapy-based and haematopoietic stem cell transplantation (HSCT) regimens for acute myeloid leukaemia (AML) in children. There has been no consensus on indication for HSCT. Reserving HSCT for high-risk and relapsed patients spare many patients from the long-term toxicity of this treatment. The results of matched unrelated donor HSCT equal family donor transplantation and the presence of a matched sibling should no longer be a transplant indication. Minimal residual disease measured by flow cytometry may identify poor responders benefitting from HSCT in first complete remission (CR1) and those with a favourable response to induction therapy who do not need HSCT even with adverse cytogenetic aberrations. FLT3-internal tandem duplication without NPM1 mutation has a very high relapse rate despite favourable response and HSCT is indicated in CR1 in these cases. Finding the optimal indications for HSCT is a delicate balance between risk of relapse and late effects.