Acute myeloid leukemia : immunologic and metabolic approaches

Le Dimethyl Ampal Thiolester (DIMATE) est un inhibiteur des aldéhydes déshydrogénases (ALDHs) de type 1 et 3. L’intérêt croissant au cours de ces dernières années pour ces enzymes intra cytoplasmiques que sont les ALDHs, s’explique par leurs utilisations comme marqueurs pour distinguer les cellules souches, saines ou cancéreuses, au sein de différents tissus, comme le tissu hématopoïétique. Le traitement des Leucémies Aiguës Myéloïdes demeure une problématique clinique majeure. En effet, malgré un taux de rémission complète moyen d’environ 70% avec les traitements conventionnels, la survie moyenne des patients porteurs d’une LAM n’excède pas les 50% à 5 ans. A ce titre, le DIMATE, semble être un médicament d’avenir. Le DIMATE présente une toxicité majeure sur plusieurs lignées leucémiques humaines et sur des cellules souches leucémiques issues de patients. De manière remarquable, le DIMATE à ces doses anti-leucémiques présente une innocuité quasi-totale sur les cellules souches hématopoïétiques saines. In vivo, chez la souris, le DIMATE permet d’éradiquer spécifiquement les cellules leucémiques humaines xénogreffées et présente en monothérapie une efficacité similaire à l’association Cytarabine + Daunorubicine qui constitue le standard thérapeutique actuel. Ces résultats encourageants vont servir de support conceptuel à la mise en place prochaine d’essais cliniques.The Dimethyl Ampal Thiolester (DIMATE) is a type 1 and 3 Aldehydes Dehydrogenases (ALDHs) inhibitor as an innovating treatment for AML. Interest in ALDH is due to its activity as a marker for identification of stem cell in different tissues. The different species of ALDHs control the levels of the endogenous apoptogenic aldehydes. Cancer cells protect themselves from the apoptogenic effect of these aldehydes by the ALDHs that oxidize them to their non-apoptogenic carboxylic acids. The vast majority of patients with AML achieve complete remission (CR) after standard induction chemotherapy. However, the majority subsequently relapses and dies of the disease. Therefore, AML remains a clinical challenge and new therapies are urgently needed. For this, DIMATE appears as a promising drug. In vitro, DIMATE is a powerful ALDH inhibitor and has a major cytotoxic activity on human AML cell lines. Moreover, DIMATE is highly active against leukemic population enriched in LSCs, but, unlike conventional chemotherapy, DIMATE is not toxic for healthy hematopoietic stem cells which retained after treatment their self-renewing and multi-lineage differentiation capacity. In immunodeficient mice, xenografted with human leukemic cells, DIMATE eradicates specifically human AML cells and spares healthy mouse hematologic cells. Moreover, DIMATE showed the same efficiency than the association Daunorubicin + Cyrabine, which is considered as the gold standard for AML induction. Results from our work open new therapeutic perspectives in AML and provide a conceptual support for initiation of a phase I-II clinical trials, but also innovating cellular therapy

Characteristics of JAK2 unmutated erythrocytosis: Distinctive traits between polycythemia vera and non-polycythemia vera patients

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Impact of Next-Generation Sequencing in Diagnosis, Prognosis and Therapeutic Management of Acute Myeloid Leukemia/Myelodysplastic Neoplasms

International audienceFor decades, the diagnosis, prognosis and thus, the treatment of acute myeloblastic leukemias and myelodysplastic neoplasms has been mainly based on morphological aspects, as evidenced by the French-American-British classification. The morphological aspects correspond quite well, in a certain number of particular cases, to particular evolutionary properties, such as acute myelomonoblastic leukemias with eosinophils or acute promyelocytic leukemias. Advances in biology, particularly “classical” cytogenetics (karyotype) and molecular cytogenetics (in situ hybridization), have made it possible to associate certain morphological features with particular molecular abnormalities, such as the pericentric inversion of chromosome 16 and translocation t(15;17) in the two preceding examples. Polymerase chain reaction techniques have made it possible to go further in these analyses by associating these karyotype abnormalities with their molecular causes, CBFbeta fusion with MYH11 and PML-RAR fusion in the previous cases. In these two examples, the molecular abnormality allows us to better define the pathophysiology of leukemia, to adapt certain treatments (all-transretinoic acid, for example), and to follow up the residual disease of strong prognostic value beyond the simple threshold of less than 5% of marrow blasts, signaling the complete remission. However, the new sequencing techniques of the next generation open up broader perspectives by being able to analyze several dozens of molecular abnormalities, improving all levels of management, from diagnosis to prognosis and treatment, even if it means that morphological aspects are increasingly relegated to the background

The contribution of single-cell analysis of acute leukemia in the therapeutic strategy

International audienceAfter decades during which the treatment of acute myeloblastic leukemia was limited to variations around a skeleton of cytarabine/anthracycline, targeted therapies appeared. These therapies, first based on monoclonal antibodies, also rely on specific inhibitors of various molecular abnormalities. A significant but modest prognosis improvement has been observed thanks to these new treatments that are limited by a high rate of relapse, due to the intrinsic chemo and immune-resistance of leukemia stem cell, together with the acquisition of these resistances by clonal evolution. Relapses are also influenced by the equilibrium between the pro or anti-tumor signals from the bone marrow stromal microenvironment and immune effectors. What should be the place of the targeted therapeutic options in light of the tumor heterogeneity inherent to leukemia and the clonal drift of which this type of tumor is capable? Novel approaches by single cell analysis and next generation sequencing precisely define clonal heterogeneity and evolution, leading to a personalized and time variable adapted treatment. Indeed, the evolution of leukemia, either spontaneous or under therapy selection pressure, is a very complex phenomenon. The model of linear evolution is to be forgotten because single cell analysis of samples at diagnosis and at relapse show that tumor escape to therapy occurs from ancestral as well as terminal clones. The determination by the single cell technique of the trajectories of the different tumor sub-populations allows the identification of clones that accumulate factors of resistance to chemo/immunotherapy ("pan-resistant clones"), making possible to choose the combinatorial agents most likely to eradicate these cells. In addition, the single cell technique identifies the nature of each cell and can analyze, on the same sample, both the tumor cells and their environment. It is thus possible to evaluate the populations of immune effectors (T-lymphocytes, natural killer cells) for the leukemia stressinduced alteration of their functions. Finally, the single cells techniques are an invaluable tool for evaluation of the measurable residual disease since not only able to quantify but also to determine the most appropriate treatment according to the sensitivity profile to immuno-chemotherapy of remaining leukemic cells

Abstract 1150: Pharmacokinetics and pharmacogenetics of liposomal cytarabine in AML patients treated with CPX-351

International audienceAbstract CPX-351 is a liposomal form encapsulating cytarabine and daunorubicin for treating Acute Myeloid Leukemia (AML) patients. Cytidine Deaminase (CDA) catabolizes free cytarabine in the liver, but to what extent it could affect as well the pharmacokinetics of liposomal cytarabine is yet to be investigated. Here we have studied the pharmacokinetics (PK) of released, liposomal and total cytarabine using a population-modeling approach in adult AML patients treated with CPX-351. Impact of CDA status (i.e., Poor Metabolizer (PM) vs. Extensive Metabolizer (EM)) on cytarabine exposure levels (AUC, trough levels, Cmax) and PK parameters were analyzed. All patients showed febrile neutropenia and one toxic-death was observed. Overall response rate was 75%. The ratio free:total cytarabine monitored in our patients was higher than expected (i.e., 47%). Inter-individual variability on pharmacokinetics parameters and subsequent exposure levels was >60%. A trend towards severe toxicities was observed in patients with higher exposure of cytarabine. Results showed that liposomal CPX-351 led to sustained exposure with reduced clearance (Cl = 0.16 L/h) and prolonged half-life (T1/2 = 28 h). Of note, liposomes were observed transiently in bone marrow on D15, with cytarabine levels 2.3-time higher than in plasma. Sequencing CDA gene was not contributive and CDA status was primarily evaluated upon phenotyping patients. PM status was found in 77% of the patients with a marked impact on cytarabine PK parameters, i.e., PM patients had higher exposure than EM patients (AUC: 5536 vs. 1784 ng/mL.h), prolonged half-life (T1/2: 33.9 vs. 13.7 h), and reduced clearance (Cl: 0.12 vs. 0.29 L/h). This pilot study suggests that despite being encapsulated in a liposomal vehicle as CPX-351, cytarabine fate in the body is highly dependent upon CDA activity, suggesting that liver metabolism is only partly skipped by the nanoparticle. Here, CDA status proved to have a major impact on cytarabine PK and possibly safety in AML patients treated with CPX-351. Indeed PM patients displayed higher exposure levels with higher risk for severe non-hematological toxicities. This study suggests that CDA status could be used as a covariate to customize CPX-351 dosing in AML patients. Citation Format: Melanie Donnette, Mourad Hamimed, Joseph Ciccolini, Regis Costello, Laure Delassus, Geoffroy Venton, Raphaelle Fanciullino. Pharmacokinetics and pharmacogenetics of liposomal cytarabine in AML patients treated with CPX-351 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1150

Successful treatment with adapted high dose methotrexate in a hemodialysis patient with primary central nervous system lymphoma: 100 mg/m2 seems sufficient

International audienceHigh dose methotrexate (HD-MTX) based chemoimmunotherapy is a central part of the standard approach to treatment of primary central nervous system lymphoma (PCNSL). Renal dysfunction leads to delayed MTX complete elimination and critical MTX concentration. Despite the recommendations, hemodialysis status should not exclude HD-MTX. We report the case of a 64 years old woman on chronic hemodialysis with PCNSL successfully treated with HD-MTX-based chemoimmunotherapy with an adjusted dose of 100mg/m2, instead of the usual dose of 3500mg/m2, and daily hemodialysis started 24h later. The patient had no significant toxicity and was in complete remission at 1 year after the end of the treatment. We argue that ESRD is not an absolute pitfall to the use of HD-MTX for hematological malignancies. Experts should consider the use of adjusted dose at 100mg/m2 as a viable therapeutic modality in ESRD patients

The Contribution of Multiplexing Single Cell RNA Sequencing in Acute Myeloid Leukemia

Decades ago, the treatment for acute myeloid leukemia relied on cytarabine and anthracycline. However, advancements in medical research have introduced targeted therapies, initially employing monoclonal antibodies such as ant-CD52 and anti-CD123, and subsequently utilizing specific inhibitors that target molecular mutations like anti-IDH1, IDH2, or FLT3. The challenge lies in determining the role of these therapeutic options, considering the inherent tumor heterogeneity associated with leukemia diagnosis and the clonal drift that this type of tumor can undergo. Targeted drugs necessitate an examination of various therapeutic targets at the individual cell level rather than assessing the entire population. It is crucial to differentiate between the prognostic value and therapeutic potential of a specific molecular target, depending on whether it is found in a terminally differentiated cell with limited proliferative potential or a stem cell with robust capabilities for both proliferation and self-renewal. However, this cell-by-cell analysis is accompanied by several challenges. Firstly, the scientific aspect poses difficulties in comparing different single cell analysis experiments despite efforts to standardize the results through various techniques. Secondly, there are practical obstacles as each individual cell experiment incurs significant financial costs and consumes a substantial amount of time. A viable solution lies in the ability to process multiple samples simultaneously, which is a distinctive feature of the cell hashing technique. In this study, we demonstrate the applicability of the cell hashing technique for analyzing acute myeloid leukemia cells. By comparing it to standard single cell analysis, we establish a strong correlation in various parameters such as quality control, gene expression, and the analysis of leukemic blast markers in patients. Consequently, this technique holds the potential to become an integral part of the biological assessment of acute myeloid leukemia, contributing to the personalized and optimized management of the disease, particularly in the context of employing targeted therapies

Successful treatment with adapted high dose methotrexate in a hemodialysis patient with primary central nervous system lymphoma: 100 mg/m2 seems sufficient

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