A pilot study on the usefulness of peripheral blood flow cytometry for the diagnosis of lower risk myelodysplastic syndromes: the "MDS thermometer"

Flow cytometric analysis of peripheral blood neutrophil myeloperoxidase expression in myelodysplastic neoplasms (MPO-MDS-Valid): protocol for a multicentre diagnostic accuracy study

INTRODUCTION

Many patients referred for suspicion of myelodysplastic neoplasm (MDS) are subjected to unnecessary discomfort from bone marrow aspiration, due to the low disease prevalence in this population. Flow cytometric analysis of peripheral blood neutrophil myeloperoxidase expression could rule out MDS with sensitivity and negative predictive value estimates close to 100%, ultimately obviating the need for bone marrow aspiration in up to 35% of patients. However, the generalisability of these findings is uncertain due to the limited sample size, the enrolment of patients at a single study site, and the reliability issues associated with laboratory-developed tests and varying levels of operator experience. This study aims to validate the accuracy attributes of peripheral blood neutrophil myeloperoxidase expression quantified by flow cytometric analysis in an independent multicentre sample.

METHODS AND ANALYSIS

The MPO-MDS-Valid project is a cross-sectional diagnostic accuracy study comparing an index test to a reference standard. Consecutive adult patients referred for suspicion of MDS are being recruited at seven university hospitals and one cancer centre in France. At each site, flow cytometric analysis of peripheral blood samples is performed by operators who are blinded to the reference diagnosis. A central adjudication committee whose members are unaware of the index test results will determine the reference diagnosis of MDS, based on cytomorphological evaluation of bone marrow performed in duplicate by experienced hematopathologists. The target sample size is 400 patients and the anticipated study recruitment completion date is 31 December 2025.

ETHICS AND DISSEMINATION

An institutional review board (Comité de Protection des Personnes Nord-Ouest III, Caen, France) approved the protocol, prior to the start of the study. Participants are recruited using an opt-out approach. Efforts will be made to publish the primary results within 6 months after study completion.

TRIAL REGISTRATION NUMBER

NCT05175469.

Flow cytometric analysis of myelodysplasia: Pre-analytical and technical issues-Recommendations from the European LeukemiaNet

BACKGROUND

Flow cytometry (FCM) aids the diagnosis and prognostic stratification of patients with suspected or confirmed myelodysplastic syndrome (MDS). Over the past few years, significant progress has been made in the FCM field concerning technical issues (including software and hardware) and pre-analytical procedures.

METHODS

Recommendations are made based on the data and expert discussions generated from 13 yearly meetings of the European LeukemiaNet international MDS Flow working group.

RESULTS

We report here on the experiences and recommendations concerning (1) the optimal methods of sample processing and handling, (2) antibody panels and fluorochromes, and (3) current hardware technologies.

CONCLUSIONS

These recommendations will support and facilitate the appropriate application of FCM assays in the diagnostic workup of MDS patients. Further standardization and harmonization will be required to integrate FCM in MDS diagnostic evaluations in daily practice.

Personalized Risk Schemes and Machine Learning to Empower Genomic Prognostication Models in Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) are characterized by variable clinical manifestations and outcomes. Several prognostic systems relying on clinical factors and cytogenetic abnormalities have been developed to help stratify MDS patients into different risk categories of distinct prognoses and therapeutic implications. The current abundance of molecular information poses the challenges of precisely defining patients' molecular profiles and their incorporation in clinically established diagnostic and prognostic schemes. Perhaps the prognostic power of the current systems can be boosted by incorporating molecular features. Machine learning (ML) algorithms can be helpful in developing more precise prognostication models that integrate complex genomic interactions at a higher dimensional level. These techniques can potentially generate automated diagnostic and prognostic models and assist in advancing personalized therapies. This review highlights the current prognostication models used in MDS while shedding light on the latest achievements in ML-based research.

Flow cytometric analysis of peripheral blood neutrophil myeloperoxidase expression for ruling out myelodysplastic syndromes: a prospective validation study

Suspicion of myelodysplastic syndromes (MDS) is the most common reason for bone marrow aspirate in elderly patients. This study aimed to prospectively validate the accuracy for flow cytometric analysis of peripheral blood neutrophil myeloperoxidase expression in ruling out MDS. We enrolled 62 consecutive patients who were referred for suspected MDS, based on medical history and peripheral blood cytopenia. The accuracy of intra-individual robust coefficient of variation (RCV) for peripheral blood neutrophil myeloperoxidase expression was assessed with a prespecified 30% threshold. Cytomorphological evaluation of bone marrow aspirate performed by experienced hematopathologists confirmed MDS in 23 patients (prevalence, 37%), unconfirmed MDS in 32 patients (52%, including 3 patients with idiopathic cytopenia of undetermined significance (ICUS)), and was uninterpretable in 7 patients (11%). The median intra-individual RCV values for neutrophil myeloperoxidase expression in peripheral blood were 37.4% (range, 30.7-54.1), 29.2% (range, 28.1-32.1), and 29.1% (range, 24.7-37.8) for patients with confirmed suspicion of MDS, ICUS, and unconfirmed suspicion of MDS, respectively (P<0.001). The area under the ROC curve was 0.92 (95% confidence interval, 0.86-0.99). An intra-individual RCV value lower than 30% ruled out MDS for 35% (i.e., 19/55) patients referred for suspected disease, with 100% sensitivity (95% CI, 85-100%) and 100% negative predictive value (95% CI, 82-100%) estimates. This study shows that flow cytometric analysis of peripheral blood neutrophil myeloperoxidase expression might obviate the need for bone marrow aspirate for 35% of patients with suspected MDS. Trial registration: ClinicalTrials.gov identifier: NCT03363399 (first posted on December 6, 2017).

Increased proportion and altered properties of intermediate monocytes in the peripheral blood of patients with lower risk Myelodysplastic Syndrome

Immune deregulation has a critical role in the pathogenesis of lower risk myelodysplastic syndromes (MDS). The cells of the macrophage/monocyte lineage have been reported to contribute to the inflammatory process in MDS through impaired phagocytosis of the apoptotic hemopoietic cells and abnormal production of cytokines. In the present study we assessed the number of peripheral blood (PB) monocyte subsets, namely the classical CD14^bright/CD16^-, intermediate CD14^bright/CD16⁺ and non-classical CD14^dim/CD16⁺ cells, in patients with lower risk (low/intermediate-I) MDS (n = 32). We also assessed the production of tumor necrosis factor (TNF)α by patient PB monocytes in response to immune stimulus as well as their transcriptome profile. Compared to age- and sex-matched healthy individuals (n = 19), MDS patients had significantly lower number of classical and increased number of intermediate monocytes. Patient intermediate monocytes displayed increased production of TNFα following stimulation with lipopolysaccharide, compared to healthy individuals. Transcriptional profiling comparison of CD16⁺ monocytes from patients and controls revealed 43 differentially expressed genes mostly associated with biological pathways/processes relevant to hemopoiesis, immune signaling and cell adhesion. These data provide evidence for the first-time that distinct monocyte subsets display abnormal quantitative and functional characteristics in lower risk MDS substantiating their role in the immune deregulation associated with the disease.

Inhibiting the NLRP3 Inflammasome With Methylene Blue as Treatment Adjunct in Myelodysplasia

Myelodysplasia refers to a group of clonal hematopoietic neoplasms characterized by genetic heterogeneity, different clinical behaviors and prognoses. Some of this group of bone marrow failure conditions have known external causes, some are of unknown origin. Within marrow, intracellular, and extracellular elements of the innate immune system are activated and contribute to creation of multiple cytogenetic abnormalities and are central to the mode of hematopoietic cell failure. Basiorka et al. showed that NLRP3 inflammasome activity is essential to the innate immune system's destruction of marrow hematopoietic cells commonly in myelodysplasia. In April 2018 Hao et al. reported that methylene blue inhibits rat NLRP3 inflammasome function. Methylene blue has been in continuous use in humans for over a century. It is associated with an eminently benign side effect profile in human use. If as in rodents, methylene blue also inhibits NLRP3 inflammasome function in human myelodysplasia a trial of adjunctive methylene blue treatment in transfusion dependent, low risk myelodysplasia where marrow inflammation and apoptosis predominates, would be worth trying.

HIGHLIGHTS

- Cytogenetic abnormalities and innate immune activation are seen in myelodysplasia

- The NLRP3 inflammasome is a core element generating marrow failure of myelodysplasia

- In April 2018 methylene blue was reported to potently inhibit NLRP3 inflammasome function

- Methylene blue has benign side effects and has been in human use for a century

- Study of methylene blue treatment of myelodysplasia would be a low-risk intervention