Caroline Bret

Background: Chimeric antigen receptor T-cell (CAR-T) therapy is associated with numerous adverse effects, among which acute kidney injury (AKI) remains poorly characterized. This study aimed to determine the incidence and risk factors of AKI following CAR-T therapy. Methods: This retrospective study was conducted among adult patients who received CAR-T cell therapy at an university hospital between April 2019 and December 2023. The incidence and risk factors for AKI, as well as its impact on overall survival and progression-free survival, were analyzed using univariate and multivariate analyses. Results: A total of 220 patients were included (mean age 63 ± 12 years), mostly treated for B-cell lymphomas. Pre-existing chronic kidney disease (CKD) was present in 26% of patients, and 24% had been admitted to the intensive care unit. The cumulative incidence of AKI was 20.5% (n = 45), occurring early after CAR-T infusion (4 days). Among AKI cases, 22% were KDIGO stage 3, and 15.6% required renal replacement therapy. In multivariate analysis, pre-existing CKD was strongly associated with AKI occurrence (adjusted OR 8.9), as was exposure to ACEI and ARBs with nephrotoxic agents (adjusted OR 2.7). Severity of cytokine release syndrome, and CAR-T–associated encephalopathy were associated with AKI in univariate analysis. Severe AKI was associated with reduced progression-free survival. Conclusions: Acute kidney injury commonly occurs following CAR-T cell therapy, and its occurrence was closely linked to pre-existing renal comorbidities and cumulative exposure to nephrotoxic agents and ACEI and ARBS. The severity of AKI was associated with reduced overall survival and progression-free survival.

Ce travail de thèse a eu pour thème principal le protéoglycane syndecan-1 au cours du myélome multiple, une hémopathie maligne caractérisée par la présence d'un clone de plasmocytes tumoraux au sein de la moelle osseuse. Syndecan-1 est un élément majeur de la physiopathologie du myélome multiple, ce protéoglycane étant au coeur d'un réseau complexe d'interactions moléculaires conditionnant le devenir des cellules plasmocytaires tumorales.Les chaînes de glycosaminoglycanes présentes sur le core protéique de syndecan-1sont responsables d'une grande partie de son activité. Nous avons ainsi caractérisé, par une approche transcriptomique, 100 gènes codant les protéines impliquées dans la synthèse et la modification de ces chaînes. Nous avons de cette manière identifié des cibles moléculairesen vue de moduler, voire d'inhiber leur activité.Dans le but d'identifier les métalloprotéinases des familles ADAM et ADAMTS susceptibles d'interagir avec syndecan-1, nous avons réalisé l'étude du profil d'expression des gènes codant ces reprolysines et leurs inhibiteurs dans les cellules de la différentiation lymphocytaire B, les cellules plasmocytaires normales et tumorales ainsi que dans l'environnement médullaire.Dans une dernière partie, nous avons évalué l'efficacité d'une approche d'inhibitiondes chaînes héparanes sulfates via l'utilisation de l'héparine. Nous observons que certaines lignées myélomateuses sont inhibées par l'héparine et ses dérivés et que ces mêmes lignées sont stimulées par l'antidote de l'héparine, le sulfate de protamine. Les mécanismes mis enjeu sont en relation avec la modulation de la biodisponibilité des facteurs permettant la croissance des cellules.

High‐grade B‐cell lymphomas (HGBCL) represent a heterogeneous group of very rare mature B‐cell lymphomas. The 4th revised edition of the WHO Classification of Tumors of Hematopoietic and Lymphoid Tissues (WHO‐HAEM) previously defined two categories of HGBCL: the so‐called double‐hit (DHL) and triple‐hit (THL) lymphomas, which were related to forms harboring MYC and BCL2 and/or BCL6 rearrangements, and HGBCL, NOS (not otherwise specified), corresponding to entities with intermediate characteristics between diffuse large B‐cell lymphoma (DLBCL) and Burkitt lymphoma (BL), without rearrangement of the MYC and BCL2, and/or BCL6 genes. In the 5th edition of the WHO‐HAEM, DHL with MYC and BCL2 rearrangements or THL were reassigned as DLBCL/HGBCL with MYC and BCL2 rearrangements (DLBCL/HGBL‐MYC/BCL2), whereas the category HGBCL, NOS remains unchanged. Characterized by an aggressive clinical presentation and a poor prognosis, HGBCL is often diagnosed at an advanced, widespread stage, leading to potential disseminated forms with a leukemic presentation, or spreading to the bone marrow (BM) or other biological fluids. Flow cytometric immunophenotypic study of these disseminated cells can provide a rapid method to identify HGBCL. However, due to the scarcity of cases, only limited data about the immunophenotypic features of HGBCL by multiparametric flow cytometry are available. In addition, identification of HGBCL cells by this technique may be challenging due to clinical, pathological, and biological features that can overlap with other distinct lymphoid malignancies, including Burkitt lymphoma (BL), diffuse large B‐cell lymphoma (DLBCL), and even B acute lymphoblastic leukemia (B‐ALL). In this study, we aimed to characterize the detailed immunophenotypic portrait of HGBCL, evaluating by multiparametric flow cytometry (MFC) the expression of 26 markers on biological samples obtained from a cohort of 10 newly‐diagnosed cases and comparing their level of expression with normal peripheral blood (PB) B lymphocytes (n = 10 samples), tumoral cells from patients diagnosed with B‐ALL (n = 30), BL (n = 13), or DLBCL (n = 22). We then proposed a new and simple approach to rapidly distinguish disseminated forms of HGBCL, BL, and DLBCL, using the combination of MFC data for CD38, BCL2, and CD39, the three most discriminative markers explored in this study. We finally confirmed the utility of the scoring system previously proposed by Khanlari to distinguish HGBCL cells from B lymphoblasts of B‐ALL. In conclusion, we described a distinct immunophenotypic portrait of HGBCL cells and proposed a strategy to differentiate these cells from other aggressive B lymphoma entities in biological samples.

BHLHE41 is a nuclear transcriptional repressor that belongs to the basic helix-loop-helix protein superfamily. BHLHE41 expression tends to be restricted to specific tissues and is regulated by environmental cues and biological events. BHLHE41 homodimerizes or heterodimerizes with various partners, influencing its transcription factor function. BHLHE41 is involved in the regulation of many physiological processes implicated in tissue/organ homeostasis, such as myogenesis, adipogenesis, circadian rhythms and DNA repair. At cellular level, BHLHE41 is involved in the regulation of mesenchymal stem cell properties, tissue-specific macrophage functions and lymphoid lineage physiology. In several cancer types, BHLHE41 modulates the expression of different transcriptional programs influencing cell cycle control, apoptosis, invasiveness, epithelial to mesenchymal transition and hypoxia response in the tumor environment. Depending on the cancer cell type, BHLHE41 can act as a tumor suppressor or an oncogene, and could be a target for innovative therapies. This review summarizes the available knowledge on BHLHE41 structure, biological functions, regulation and potential partners, as well as its role in physiological processes, and its implication in major cancer steps.

Plasma cells (PCs) are highly specialized cells representing the end stage of B-cell differentiation. We have shown that PC differentiation can be reproduced in vitro using elaborate culture systems. The molecular changes occurring during PC differentiation are recapitulated in this in vitro differentiation model. However, a major challenge exists to decipher the spatiotemporal epigenetic and transcriptional programs that drive the early stages of PC differentiation. We combined single cell (sc) RNA sequencing (RNA-seq) and assay for transposase-accessible chromatin with high throughput sequencing (scATAC-seq) to decipher the trajectories involved in PC differentiation. ScRNA-seq experiments revealed a strong heterogeneity of the preplasmablastic and plasmablastic stages. Among genes that were commonly identified using scATAC-seq and scRNA-seq, we identified several transcription factors with significant stage specific potential importance in PC differentiation. Interestingly, differentially accessible peaks characterizing the preplasmablastic stage were enriched in motifs of BATF3, FOS and BATF, belonging to activating protein 1 (AP-1) transcription factor family that may represent key transcriptional nodes involved in PC differentiation. Integration of transcriptomic and epigenetic data at the single cell level revealed that a population of preplasmablasts had already undergone epigenetic remodeling related to PC profile together with unfolded protein response activation and are committed to differentiate in PC. These results and the supporting data generated with our in vitro PC differentiation model provide a unique resource for the identification of molecular circuits that are crucial for early and mature PC maturation and biological functions. These data thus provide critical insights into epigenetic- and transcription–mediated reprogramming events that sustain PC differentiation.

Background: Multiparametric flow cytometry (MFC) is an essential diagnostic tool in B acute lymphoblastic leukemia (B ALL) to determine the B‐lineage affiliation of the blast population and to define their complete immunophenotypic profile. Most MFC strategies used in routine laboratories include leukemia‐associated phenotype (LAP) markers, whose expression profiles can be difficult to interpret. The aim of our study was to reach a better understanding of 7 LAP markers' landscape in B ALL: CD9, CD21, CD66c, CD58, CD81, CD123, and NG2.Methods: Using a 10‐color MFC approach, we evaluated the level of expression of 7 LAP markers including CD9, CD21, CD66c, CD58, CD81, CD123, and NG2, at the surface of normal peripheral blood leukocytes (n = 10 healthy donors), of normal precursor B regenerative cells (n = 40 uninvolved bone marrow samples) and of lymphoblasts (n = 100 peripheral blood samples or bone marrow samples from B ALL patients at diagnosis). The expression profile of B lymphoblasts was analyzed according the presence or absence of recurrent cytogenetic aberrations. The prognostic value of the 7 LAP markers was examined using Maxstat R algorithm.Results: In order to help the interpretation of the MFC data in routine laboratories, we first determined internal positive and negative populations among normal leukocytes for each of the seven evaluated LAP markers. Second, their profile of expression was evaluated in normal B cell differentiation in comparison with B lymphoblasts to establish a synopsis of their expression in normal hematogones. We then evaluated the frequency of expression of these LAP markers at the surface of B lymphoblasts at diagnosis of B ALL. CD9 was expressed in 60% of the cases, CD21 in only 3% of the cases, CD58 in 96% of the cases, CD66c in 45% of the cases, CD81 in 97% of the cases, CD123 in 72% of the cases, and NG2 in only 2% of the cases. We confirmed the interest of the CD81/CD58 MFI expression ratio as a way to discriminate hematogones from lymphoblasts. We observed a significant lower expression of CD9 and of CD81 at the surface of B lymphoblasts with a t(9;22)(BCR‐ABL) in comparison with B lymphoblasts without any recurrent cytogenetic alteration (p = 0.0317 and p = 0.0011, respectively) and with B lymphoblasts harboring other cytogenetic recurrent abnormalities (p = 0.0032 and p < 0.0001, respectively). B lymphoblasts with t(1;19) at diagnosis significantly overexpressed CD81 when compared with B lymphoblasts with other recurrent cytogenetic abnormalities or without any recurrent alteration (p = 0.0001). An overexpression of CD58 was also observed in the cases harboring this abnormal cytogenetic event, when compared with B lymphoblasts with other recurrent cytogenetic abnormalities (p = 0.030), or without any recurrent alteration (p = 0.0002). In addition, a high expression of CD123, of CD58 and of CD81 was associated with a favorable prognosis in our cohort of pediatric and young adult B ALL patients. We finally built a risk score based on the expression of these 3 LAP markers, this scoring approach being able to split these patients into a high‐risk group (17%) and a better outcome group (83%, p < 0.0001).Conclusion: The complexity of the phenotypic signature of lymphoblasts at diagnosis of B ALL is illustrated by the variability in the expression of LAP antigens. Knowledge of the expression levels of these markers in normal leukocytes and during normal B differentiation is crucial for an optimal interpretation of diagnostic cytometry results and serves as a basis for the biological follow‐up of B ALL.

Diffuse large B-cell lymphoma (DLBCL) is the most common hematological malignancy. Although more than half of patients with DLBCL achieve long-term remission, the majority of remaining patients succumb to the disease. As abnormal iron homeostasis is implicated in carcinogenesis and the progression of many tumors, we searched for alterations in iron metabolism in DLBCL that could be exploited to develop novel therapeutic strategies. Analysis of the iron metabolism gene expression profile of large cohorts of patients with DLBCL established the iron score (IS), a gene expression–based risk score enabling identification of patients with DLBCL with a poor outcome who might benefit from a suitable targeted therapy. In a panel of 16 DLBCL cell lines, ironomycin, a promising lysosomal iron-targeting small molecule, inhibited DLBCL cell proliferation at nanomolar concentrations compared with typical iron chelators. Ironomycin also induced significant cell growth inhibition, ferroptosis, and autophagy. Ironomycin treatment resulted in accumulation of DNA double-strand breaks, delayed progression of replication forks, and increased RPA2 phosphorylation, a marker of replication stress. Ironomycin significantly reduced the median number of viable primary DLBCL cells of patients without major toxicity for nontumor cells from the microenvironment and presented low toxicity in hematopoietic progenitors compared with conventional treatments. Significant synergistic effects were also observed by combining ironomycin with doxorubicin, BH3 mimetics, BTK inhibitors, or Syk inhibitors. Altogether, these data demonstrate that a subgroup of high-risk patients with DLBCL can be identified with the IS that can potentially benefit from targeting iron homeostasis.Significance:Iron homeostasis represents a potential therapeutic target for high-risk patients with DLBCL that can be targeted with ironomycin to induce cell death and to sensitize tumor cells to conventional treatments.

Leukocyte-associated immunoglobulin (Ig)-like receptor 1 (LAIR1, CD305) belongs to the family of immune-inhibitory receptors and is widely expressed on hematopoietic mature cells, particularly on immune cells. Four different types of ligands of LAIR1 have been described, including collagens, suggesting a potential immune-regulatory function on the extracellular matrix. By modulating cytokine secretion and cellular functions, LAIR1 displays distinct patterns of expression among NK cell and T/B lymphocyte subsets during their differentiation and cellular activation and plays a major negative immunoregulatory role. Beyond its implications in physiology, the activity of LAIR1 can be inappropriately involved in various autoimmune or inflammatory disorders and has been implicated in cancer physiopathology, including hematological neoplasms. Its action as an inhibitory receptor can result in the dysregulation of immune cellular responses and in immune escape within the tumor microenvironment. Furthermore, when expressed by tumor cells, LAIR1 can modulate their proliferation or invasion properties, with contradictory pro- or anti-tumoral effects depending on tumor type. In this review, we will focus on its role in normal physiological conditions, as well as during pathological situations, including hematological malignancies. We will also discuss potential therapeutic strategies targeting LAIR1 for the treatment of various autoimmune diseases and cancer settings.