Céline Callens

Targeting iron homeostasis induces cellular differentiation and synergizes with differentiating agents in acute myeloid leukemia

Differentiating agents have been proposed to overcome the impaired cellular differentiation in acute myeloid leukemia (AML). However, only the combinations of all-trans retinoic acid or arsenic trioxide with chemotherapy have been successful, and only in treating acute promyelocytic leukemia (also called AML3). We show that iron homeostasis is an effective target in the treatment of AML. Iron chelating therapy induces the differentiation of leukemia blasts and normal bone marrow precursors into monocytes/macrophages in a manner involving modulation of reactive oxygen species expression and the activation of mitogen-activated protein kinases (MAPKs). 30% of the genes most strongly induced by iron deprivation are also targeted by vitamin D3 (VD), a well known differentiating agent. Iron chelating agents induce expression and phosphorylation of the VD receptor (VDR), and iron deprivation and VD act synergistically. VD magnifies activation of MAPK JNK and the induction of VDR target genes. When used to treat one AML patient refractory to chemotherapy, the combination of iron-chelating agents and VD resulted in reversal of pancytopenia and in blast differentiation. We propose that iron availability modulates myeloid cell commitment and that targeting this cellular differentiation pathway together with conventional differentiating agents provides new therapeutic modalities for AML.

Clinical Impact of NOTCH1 and/or FBXW7 Mutations, FLASH Deletion, and TCR Status in Pediatric T-Cell Lymphoblastic Lymphoma

PURPOSE Pediatric T-cell lymphoblastic lymphomas (T-LBL) are commonly treated on T-cell acute lymphoblastic leukemia (T-ALL) -derived protocols. Therapeutic stratification based on response to the prephase treatment and on minimal residual disease assessment is well established in T-ALL but is not easy to extrapolate to T-LBL. The identification of molecular prognostic markers at diagnosis in T-LBL could provide an alternative for early therapeutic stratification. Our study determines the frequency and prognostic value of NOTCH1/FBXW7 mutations (N/F(mut)), FLASH deletion at chromosome 6q, and TCR rearrangements in a prospective cohort of pediatric T-LBL. PATIENTS AND METHODS Pathologic samples were obtained at diagnosis for 54 patients treated according to the EuroLB02 protocol in France. N/F(mut) were identified by direct sequencing and allelic dosage was used to detect FLASH and TCRγ deletions, which were interpreted in conjunction with TCRγ, TCRβ, and TCRδ rearrangements. RESULTS N/F(mut) were found in 55% of T-LBL patients, in whom they were associated with improved event-free survival (P < .01) and overall survival (P < .01). FLASH monoallelic deletions were observed in 18% of patients; they were predominantly N/F wild-type (six of nine) and tended to be of inferior prognosis (P = .09). Absence of biallelic TCRγ deletion (ABD) was seen in 7%, all of which were N/F(mut) and identified a poor prognosis group (P = .02). On multivariate analysis of N/F(mut), TCRγ ABD, and FLASH deletion, only N/F(mut) was an independent factor for good prognosis. CONCLUSION Mutational status of NOTCH1/FBXW7 represents a promising marker for early therapeutic stratification in pediatric T-LBL.

Enteropathy associated T cell lymphoma in celiac disease: A large retrospective study

Abstract Introduction Prognosis of enteropathy-associated T cell lymphoma is poor but predictors of survival remain ill-defined. How clinical presentation, pathological features and therapies influence outcome was evaluated in 37 thoroughly characterized patients with celiac disease and T-cell lymphoma. Patients and methods Medical files were studied retrospectively. Lymphoma and intestinal mucosa were analysed by histopathology, multiplex PCR and intestinal intraepithelial lymphocytes phenotyping. Survival and prognostic factors were analysed using Kaplan–Meier curves with Logrank test and Cox Model. Results Lymphoma complicated non clonal enteropathy, celiac disease (n =15) and type I refractory celiac disease (n =2) in 17 patients and clonal type II refractory celiac disease in 20 patients. Twenty-five patients underwent surgery with resection of the main tumour mass in 22 cases. In univariate analysis, non clonal celiac disease, serum albumin level>21.6g/L at diagnosis, chemotherapy and surgical resection predicted good survival (p =0.0007, p <0.0001, p <0.0001, p <0.0001, respectively). In multivariate analysis, serum albumin level>21.6g/L, chemotherapy and reductive surgery were all significantly associated with increased survival (p <0.002, p <0.03, p <0.03, respectively). Conclusions Our study underlines the prognostic value of celiac disease type in patients with T-cell lymphoma, and suggests that a combination of nutritional, chemotherapy and reductive surgery may improve survival.

Polymeric IgA1 controls erythroblast proliferation and accelerates erythropoiesis recovery in anemia

Anemia because of insufficient production of and/or response to erythropoietin (Epo) is a major complication of chronic kidney disease and cancer. The mechanisms modulating the sensitivity of erythroblasts to Epo remain poorly understood. We show that, when cultured with Epo at suboptimal concentrations, the growth and clonogenic potential of erythroblasts was rescued by transferrin receptor 1 (TfR1)-bound polymeric IgA1 (pIgA1). Under homeostatic conditions, erythroblast numbers were increased in mice expressing human IgA1 compared to control mice. Hypoxic stress of these mice led to increased amounts of pIgA1 and erythroblast expansion. Expression of human IgA1 or treatment of wild-type mice with the TfR1 ligands pIgA1 or iron-loaded transferrin (Fe-Tf) accelerated recovery from acute anemia. TfR1 engagement by either pIgA1 or Fe-Tf increased cell sensitivity to Epo by inducing activation of mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) signaling pathways. These cellular responses were mediated through the TfR1-internalization motif, YXXΦ. Our results show that pIgA1 and TfR1 are positive regulators of erythropoiesis in both physiological and pathological situations. Targeting this pathway may provide alternate approaches to the treatment of ineffective erythropoiesis and anemia.

Recent advances in adult T-cell leukemia therapy: focus on a new anti-transferrin receptor monoclonal antibody.

HTLV-I is an endemic retrovirus responsible for the adult T-cell leukemia/lymphoma (ATLL). This aggressive lymphoid proliferation is associated with a bad prognosis due to the resistance of HTLV-I-infected cells to most classical chemotherapeutic agents. Here we review recent advances in ATLL immunotherapy. We particularly focus on promising data from our group, characterizing a new mouse monoclonal antibody (mAb A24) against the human transferrin receptor (TfR-1). Monoclonal antibodies to target cell differentiation markers on ATLL cells have already been proposed as therapeutic agents. However, in clinical trials acute forms of ATLL were resistant to these immunotherapies. A24 binds TfR-1 (Kd 2.7 nM) and competes with transferrin for receptor binding. It blocks the proliferation of malignant cells (TfR-1high), such as HTLV-I-infected T cells but not of resting cells. A24 induces TfR-1 endocytosis in lysosomal compartments where the receptor is degraded leading to intracellular iron deprivation. In HTLV-I-infected cells, A24 targets and induces apoptosis of both chronic and acute ATLL forms, independent of antibody aggregation, antibody-dependent cellular cytotoxicity and/or complement addition. The antibody efficacy was confirmed in animal models. We are currently developing strategies to use A24 in clinical trials.

The prognosis of CALM-AF10-positive adult T-cell acute lymphoblastic leukemias depends on the stage of maturation arrest

CALM-AF10 (also known as PICALM-MLLT10) is the commonest fusion protein in T-cell acute lymphoblastic leukemia, but its prognostic impact remains unclear. Molecular screening at diagnosis identified CALM-AF10 in 30/431 (7%) patients with T-cell acute lymphoblastic leukemia aged 16 years and over and in 15/234 (6%) of those aged up to 15 years. Adult CALM-AF10-positive patients were predominantly (72%) negative for surface (s)CD3/T-cell receptor, whereas children were predominantly (67%) positive for T-cell receptor. Among 22 adult CALM-AF10-positive patients treated according to the LALA94/GRAALL03-05 protocols, the poor prognosis for event-free survival (P=0.0017) and overall survival (P=0.0014) was restricted to the 15 T-cell receptor-negative cases. Among CALM-AF10-positive, T-cell receptor-negative patients, 82% had an early T-cell precursor phenotype, reported to be of poor prognosis in pediatric T-cell acute lymphoblastic leukemia. Early T-cell precursor acute lymphoblastic leukemia corresponded to 22% of adult LALA94/GRAALL03-05 T-cell acute lymphoblastic leukemias, but had no prognostic impact per se. CALM-AF10 fusion within early T-cell precursor acute lymphoblastic leukemia (21%) did, however, identify a group with a poor prognosis with regards to event-free survival (P=0.04). CALM-AF10 therefore identifies a poor prognostic group within sCD3/T-cell receptor negative adult T-cell acute lymphoblastic leukemias and is over-represented within early T-cell precursor acute lymphoblastic leukemias, in which it identifies patients in whom treatment is likely to fail. Its prognosis and overlap with early T-cell precursor acute lymphoblastic leukemia in pediatric T-cell acute lymphoblastic leukemia merits analysis. The clinical trial GRAALL was registered at Clinical Trials.gov number NCT00327678.

Extensive molecular mapping of TCRα/δ- and TCRβ-involved chromosomal translocations reveals distinct mechanisms of oncogene activation in T-ALL

Chromosomal translocations involving the TCR loci represent one of the most recurrent oncogenic hallmarks of T-cell acute lymphoblastic leukemia (T-ALL) and are generally believed to result from illegitimate V(D)J recombination events. However, molecular characterization and evaluation of the extent of recombinase involvement at the TCR-oncogene junction has not been fully evaluated. In the present study, screening for TCRβ and TCRα/δ translocations by FISH and ligation-mediated PCR in 280 T-ALLs allowed the identification of 4 previously unreported TCR-translocated oncogene partners: GNAG, LEF1, NKX2-4, and IL2RB. Molecular mapping of genomic junctions from TCR translocations showed that the majority of oncogenic partner breakpoints are not recombinase mediated and that the regulatory elements predominantly used to drive oncogene expression differ markedly in TCRβ (which are exclusively enhancer driven) and TCRα/δ (which use an enhancer-independent cryptic internal promoter) translocations. Our data also imply that oncogene activation takes place at a very immature stage of thymic development, when Dδ2-Dδ3/Dδ3-Jδ1 and Dβ-Jβ rearrangements occur, whereas the bulk leukemic maturation arrest occurs at a much later (cortical) stage. These observations have implications for T-ALL therapy, because the preleukemic early thymic clonogenic population needs to be eradicated and its disappearance monitored.

Enteropathy-Associated T-Cell Lymphoma Complicating an Autoimmune Enteropathy

Enteropathy-associated T-cell lymphoma (EATL) is a rare non-Hodgkin lymphoma frequently associated with celiac disease. We report a case of EATL complicating adult autoimmune enteropathy (AIE). Analysis of phenotype, rearrangements in T-cell receptor genes, and chromosome alterations by high-resolution comparative genomic hybridization identified features distinct from those described for types I and II EATL. Furthermore, EATL arose from a single T-cell clone that had been present for several years in AIE-associated, oligoclonal, intestinal T-cell infiltrate. Emerging T-cell clones should be monitored in patients with AIE who receive long-term immunosuppressive therapy.

Deferasirox and Vitamin D Improves Overall Survival in Elderly Patients with Acute Myeloid Leukemia after Demethylating Agents Failure

The prognosis of acute myeloid leukemia (AML) in elderly (≥65 years) patients is poor and treatment remains non-consensual especially for those who are not eligible for intensive therapies. Our group has shown that in vitro the iron chelator deferasirox (DFX) synergizes with vitamin D (VD) to promote monocyte differentiation in primary AML cells. Herein, we present results from a retrospective case-control study in which the association of DFX (1–2 g/d) and 25-hydroxycholecalciferol (100,000 IU/week) (DFX/VD) was proposed to patients following demethylating agents failure. Median survival of patients treated with DFX/VD combination (n = 17) was significantly increased in comparison with matched patients receiving best supportive care (BSC) alone (n = 13) (10.4 versus 4 months respectively). In addition, the only factor associated to an increased overall survival in DFX/VD-treated patients was serum VD levels. We conclude that DFX/VD treatment correlated with increased overall survival of AML patients in this retrospective cohort of elderly patients.

Peripheral blood 8 colour flow cytometry monitoring of hairy cell leukaemia allows detection of high-risk patients.

Although purine analogues have significantly improved the outcome of hairy cell leukaemia (HCL) patients, 30–40% relapse, illustrating the need for minimal residual disease (MRD) markers that can aid personalized therapeutic management. Diagnostic samples from 34 HCL patients were used to design an 8‐colour flow cytometry (8‐FC) tube for blood MRD (B/RD) analysis (188 samples) which was compared to quantitative IGH polymerase chain reaction (Q‐PCR) on 83 samples and to qualitative consensus IGH PCR clonality analysis on 165 samples. Despite heterogeneous HCL phenotypes at diagnosis, discrimination from normal B lymphocytes was possible in all cases using a single 8‐FC tube, with a robust sensitivity of detection of 10−4, comparable to Q‐PCR at this level, but preferable in terms of informativeness, simplicity and cost. B/RD assessment of 15 patients achieving haematological complete remission after purine analogues was predictive of a clinically significant relapse risk: with a median follow‐up of 95 months; only one of the nine patients with reproducible 8‐FC B/RD levels below 10−4 (B/RDneg) relapsed, compared to 5/6 in the B/RDpos group (P = 0·003). These data demonstrate the clinical interest of a robust 8‐FC HCL B/RD strategy that could become a surrogate biomarker for therapeutic stratification and new drug assessment, which should be evaluated prospectively.