Welcome to the MDS 2023 Congress Calendar

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Mutations in RNA splicing factors are the single most common class of genomic alterations in patients with myelodysplastic syndromes (MDS) and also occur in the setting of clonal hematopoiesis which predates MDS for many patients. Splicing factor mutations serve as attractive therapeutic targets as they frequently occur as early initiating events, are present in dominant clones, and are found in cancers with few effective treatment options. Spliceosomal mutations in SF3B1, SRSF2 and U2AF1 typically harbor mutually-exclusive heterozygous mutations and co-expression of these mutations is intolerable to cells. Furthermore, several studies have shown that splicing mutant cells are preferentially dependent on wild-type spliceosome function with deletion of the wild-type allele in splicing factor mutant cancer cells leading to cell death across different cancer subtypes with mutations in SF3B1, SRSF2, or U2AF1. These data highlight the potential vulnerability of splicing factor mutant cells to global perturbations in splicing catalysis and provide a therapeutic rationale for targeting splicing to trigger cell death.

This presentation will discuss several means to therapeutically target splicing factor mutant MDS. These include small molecules which bind to the SF3b component of the spliceosome, RBM39 degrading compounds, small molecule inhibitors targeting U2AF splicing interactions, and a number of enzymes which place post-translational modifications on RNA splicing factors. For this latter category we will specifically discuss enzymatic inhibitors of CLK and DYRK kinases as well as PRMT inhibitors.

Beyond chemicals, this presentation will also discuss a suite of synthetic RNA species which are specifically recognized by mutant splicing factors to drive selective gene expression. We have harnessed this approach to selectively eliminate splicing factor mutant cells but also to identify drugs and proteins required by the mutant spliceosome.

Finally, research from our laboratories has identified that the most common spliceosomal mutations alter RNA recognition in a sequence-specific manner to cause widespread mis-splicing. This widespread production of mis-spliced mRNAs, many of which encode novel peptides, could result in high levels of neoantigen production. Indeed, our preliminary studies have identified such putative neoantigens that are generated via mis-splicing arising from oncogenic spliceosomal mutations, presented by MHC class I, and capable of stimulating a cytotoxic T cell response. This work will also be discussed.

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Health Literacy is defined as “people’s knowledge, motivation and competences to access, understand, appraise, and apply health information in order to make judgments and take decisions in everyday life concerning healthcare, disease prevention and health promotion to maintain or improve quality of life during the life course” (Sørensen et al. BMC Public Health 2012). Authors like Nutbeam (Health Promot Int 2000) distinguish three skills:

- functional literacy, which includes basic skills in reading and writing necessary to understand health information;

- communicative literacy, which corresponds to the necessary advanced skills to communicate or interact with the healthcare system;

- and critical literacy to analyse the information obtained to act at best.

Many studies demonstrated that health literacy is limited in a considerable proportion of the general population, with a social gradient. Socioeconomically disadvantaged groups present with the weakest health literacy levels, suggesting that differences in health literacy levels contribute to health disparities.

Regarding patients more specifically, a systematic review (Berkman et al. Ann Intern Med 2011) concluded that low health literacy is associated with poorer health outcomes and poorer use of health care services. Indeed, after a first review highlighting that low health literacy was associated with poorer health related knowledge and comprehension, the 2011 update showed that low health literacy was also associated with:

- differential use of certain health care services (including increased hospitalizations and emergency care),

- a poorer ability to demonstrate taking medications properly,

- and among elderly persons with poorer overall health status and higher mortality.

A more recent review focusing on cancer patients (Holden et al. PLoS ONE 2021) also showed that lower health literacy is associated with greater difficulties understanding and processing cancer related information, poorer quality of life and poorer experience of care.

Despite health literacy is multidimensional, most research focused on of functional HL. A first challenge is therefore to help people better understand their disease.

In the context of a highly complex potentially lethal disease such as MDS, it is of utmost importance to optimize the information conveyed to patients. However, MDS can be poorly understood by patients (and even physicians) as they involves several levels of complexity because of various systems of classification, heterogeneous prognosis, and variable treatment. Moreover as MDS patients are frequently older they are more likely to have a lower level of functional health literacy. Consistently the few data available on MDS patients show how difficult it is to understand MDS, its prognosis and the reasons for prescribing or not some treatments.

Therefore, lower health literacy or insufficient information might result in an insufficient access and adherence to MDS treatments that could translate in poorer health outcomes. It might help to explain the poorer survival among elderly MDS patients with lower education or living in socioeconomically disadvantaged neighbourhoods (Larfors et al. Eur J Haematol. 2021).

To our knowledge, very few studies addressed health literacy in MDS patients. A study (Ousseine et al. Leuk Research 2018) showed that inadequate functional health literacy was frequent (37%) and that it was associated with MDS related distress. “You and MDS - An Animated Patient’s Guide to Myelodysplastic Syndromes” was developed using visual formats of learning to address patient barriers to health literacy. Its retrospective evaluation demonstrates wide reach, highlighting the needs for such accessible, easy to follow, evidence-based resources (Sallman et al. Leuk Res Rep 2022).

In conclusion, more studies are needed to confirm the negative role of lower health literacy in MDS patients and to develop interventions able to improve MDS patients’ outcomes.

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Flow cytometry analysis of the abnormal partition of peripheral blood monocyte subsets supports chronic myelomonocytic leukemia (CMML) diagnosis and entered WHO criteria in 2022. An increased fraction of classical monocytes (CD14⁺/CD16^-) over 94% of total monocytes (at the detriment of non-classical monocytes (CD14^-/CD16⁺)) is a characteristic feature of CMML. This abnormal monocyte subset repartition is rarely observed in other diseases and reactive monocytosis. When this parameter is blurred by systemic inflammation promoting the generation of intermediate monocytes (CD14⁺/CD16⁺), a decrease in the fraction of Slan+ non-classical monocytes (CD14⁺/CD16^-/SLan⁺) below 1.7% of total monocytes substitutes to classical monocyte fraction increase and support CMML diagnosis. Importantly, this abnormal partition of monocytes is one of the rare unifying features of an otherwise highly heterogeneous disease. We have shown that classical monocyte accumulation is due to a block in their conversion to non-classical subset as a consequence of abnormal DNA methylation, particularly on the promoter of miR150, a microRNA involved in monocyte conversion. Besides, in patients who respond to demethylating agents, a normal partition of monocyte subsets is restored despite the limited impact of the treatment on mutant allele burden. Thus, flow cytometry analysis of monocyte subset repartition, whose diagnostic interest has increased with the decrease in the absolute monocyte count defining monocytosis, is also useful to monitor therapeutic response to epidrugs.

Flow cytometry analysis of PB cells can be used to stratify CMML patients at diagnosis. Cytological detection of immature myeloid cells in the PB is not part of commonly used CMML prognostic scores. Flow analysis of PB cells detects and quantifies immature granulocytes (IGran) as CD45^low, CD33⁺, CD11b⁺, HLA-DR^-, CD14^-, CD15⁺, CD24⁺, CD66b⁺ low density cells. Whole exome sequencing of sorted IGran and monocytes showed that IGran accumulation does not indicate subclonal evolution. IGran behave as myeloid-derived suppressive cells (G-MDSC). Bulk and single cell RNA sequencing of IGran revealed an increase production of inflammatory cytokines, including CXCL8. We observed that CXCL-8 could inhibit the proliferation of wild-type HSPC while having no impact on clonal HSPCs in which CXCL8 receptors are epigenetically down-regulated. The accumulation of IGran among myeloid cells correlates with WBC count, decreased hemoglobin level and lymphocyte fraction, and ASXL1 and SRSF2 gene mutants. An IGran fraction >14% of circulating myeloid cells or an IGran absolute number >0.4x10⁹/L correlates with decreased event-free survival or overall survival and multivariate analysis indicates that IGran quantification is independent of other prognostic factors.

Flow cytometry analysis of bone marrow cells is a less convenient assay. Nevertheless, it was shown to efficiently detect plasmacytoid dendritic cells whose accumulation in ~20% of CMML patients correlates with regulatory T cell fraction and an increase risk of acute leukemia transformation.

Together, these results argue for the routine use of flow quantification of PB cell populations at CMML diagnosis as a contribution to CMML diagnosis and prognostication. New techniques such as spectral flow and mass cytometry will allow generating a detailed atlas of PB myeloid cells in CMML patients and potentially identify additional diagnostic and prognostic features in this disease.

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Malignant myeloid disorders outside of acute leukemias are rare in childhood and defy simple nosology and definition. Evidently, MDS and MPN categories that have been developed and adapted for adult disease cannot be readily applied to pediatric patients. After decades in which differential diagnosis was mainly the domain of microscopy and cytogenetics, the field has undergone dynamic development in recent years, not least through the application of modern molecular techniques such as next-generation sequencing. These findings have also made it clear that a significant proportion of cases are associated with an underlying genetic predisposition.

MDS in children are characterized by diverse clinical manifestation, challenging bone marrow morphology, and variable disease course. They exhibit a distinct mutational landscape differing significantly from that in adults, resulting in a different and specific set of parameters for prognostication and risk assessment. For a steadily increasing proportion of cases, a constitutional genetic abnormality can be determined. The phenotype of hypoplastic myelodysplastic syndromes of childhood overlaps broadly with that of the classical congenital bone marrow failure disorders, which poses diagnostic and therapeutic problems. Fortunately, it is becoming increasingly possible to delineate these diseases at the genetic level. This in turn yields interesting insight into the pathogenesis, expected clonal evolution, and options for treatment.

JMML is a malignant stem cell disease that occurs in early childhood and has both myelodysplastic and myeloproliferative features. Although it can be highly diverse in clinical and hematologic presentation, its pathogenesis can be traced to one fundamental common denominator, the deregulation of the Ras-MAPK signaling cascade. However, within this unifying principle, disease varieties with surprisingly different course and prognosis can be defined depending on the nature of the driver mutation, calling for specific therapeutic approaches. Since JMML is largely unresponsive to conventional chemotherapy, it has long been a domain of allogeneic stem cell transplantation. Genomic studies and especially epigenetic discoveries have recently been instrumental in refining and individualizing the traditional "one HSCT fits all" approach. Because of its clearly defined molecular pathogenesis, JMML is an obvious field for the development of targeted therapy. In addition, clinical observations and experimental findings suggest an important role of tumor immunity in the successful eradication of JMML, shifting current research interests towards the therapeutic exploitation of antileukemic immune mechanisms.

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Allogeneic hematopoietic cell transplantation (allo-HCT) is the only option for patients with Myelodysplastic syndrome (MDS) that offers the potential for long-term disease-free survival in 30–70% of recipients. Results from HLA-identical sibling and completely matched (8/8 or 10/10) unrelated donors (MUD) are comparable albeit the non-relapse mortality is slightly higher after MUD transplantation

In patients without an HLA-matched sibling donor or matched unrelated donor , cord blood or a family haploidentical donor are alternative options. Since the introduction of posttransplant cyclophosphamide (PTCy) the numbers of hapo-identical stem cell transplantation is rapidly increasing for patients with leukemia and also for MDS.

The European Group for Blood and Marrow Transplantation (EBMT) studied in 2017 the effect of PTCy as GvHD prophylaxis for haploidentical transplantation in MDS patients. A total of 228 patients transplanted from a mismatched HLA-related donor between 2007 and 2014 were studied. One hundred ninety-four patients received a T-cell replete transplant and 102 patients received PTCy as graft-versus-host disease (GVHD) prophylaxis. The cumulative incidences of acute and chronic GVHD in PTCy vs other patients were 25% vs 37% and 37% vs 24%, respectively. The cumulative incidence of nonrelapse mortality was 55% in patients who did not receive PTCy and 41% in patients who did receive PT-CY. Three-year overall survival was 28% in no PT-CY patients and 38% in PT-CY patients, suggesting PTCy is the favorable GvHD prophylaxis in haplo-identical stem cell transplantation in MDS.

A further comparison of haplo-identical allo-HCT with PTCy and mismatched unrelated/cord blood (MMUD/CB) donors showed lower non-relapse mortality, acute GVHD, and better overall survival for HD when compared to both MMUD and Cord blood transplantation.

To compare Haplo-allo HCT with HLA identical sibling transplantation the EBMT investigated the outcome of 1414 matched sibling (MSD) with 415 haplo-identical donors (HD) transplanted with post-transplant cyclophosphamide (PTCy) as GVHD prophylaxis between 2014 and 2017. Two-year overall (OS) and Progression (PFS) survival with MSD were significantly better at 58% compared with 50%, p ≤ 0.001, and 51% vs 47%, p = 0.029, after Haplo-alloHCT. Relapse at 2 years was lower aftre Haplo-Hallo-HCT than with MSD 23% vs 29% (p = 0.016). Non relapse mortality (NRM) was also higher after Haplo HCT. Transplants with haploidentical donors result in reasonable long-term outcome if PTCy is used as GvHD prophylaxis and justifying it’s use when no HLA identical sibling or MUD is available.

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The successful remissions in hematological diseases after treatment with autologous CAR T cells is attracting growing interest for the treatment of various malignancies including MDS. With increasing numbers of patients, the reproducible manufacture of high-quality clinical-grade CAR T cells is becoming an ever-greater challenge. New processing techniques, quality-control mechanisms, and logistic developments are required to meet both medical needs and regulatory restrictions. Still, personalized manufacturing is time consuming and expensive. Results with automated manufacturing gives rise for improvement in both centralized and decentralized manufacturing units. However, a modular, open and transferable system with AI-mediated robotics and digital control as well as the respective automated documentation of all in process parameters is still missing in order to address 100 fold more patients. In addition, there are no harmonized rules for patient selection regarding the leukapheresis starting material and surrogate marker are nearly missing to predict production failure. In several cases, failure in manufacturing appears because the patients are heavily pre-treated and this can influence the fitness of the cells substantially. Allogeneic CAR effector cells, such as CAR NK cells play an increasing role to overcome the limitations in autologous CAR T cell manufacturing. Next, the switch from lentiviral to AAV or non viral gene transfer has opened a platform for improved safety and decreased manufacturing costs, respectively. This will be discussed in the context of current knowledge with a special view to the treatment of patients suffering from MDS, respectively.