Abstract 3269: Rebalancing systemic and cellular energy dysmetabolism in Chronic Lymphocytic Leukemia through exercise training

STAT3-Driven, Aberrantly Expressed Lipoprotein Lipase Mediates Free Fatty Acid Metabolism in Chronic Lymphocytic Leukemia Cells

Lipids and Their Effects in Chronic Lymphocytic Leukemia

Daratumumab Decreases Treg-Mediated Immunosuppression and Potentiates CD8+ T-Cell-Induced Killing of Chronic Lymphocytic Leukemia (CLL) Cells Ex Vivo

Infiltration of Malignant B Cells Suppresses and Re-Organizes Lymph Node Fibroblasts in Chronic Lymphocytic Leukemia and Mantle Cell Lymphoma

Chronic lymphocytic leukemia (CLL) cells undergo, during their life, iterative cycles of re-activation and subsequent clonal expansion. We previously demonstrated that the antidiabetic drug metformin, known to also inhibit oxidative phosphorylation (OXPHOS), inhibits cell cycle entry of leukemic cells derived ex-vivo from the peripheral blood of CLL patients and stimulated in vitro by cell culture systems that recreate a microenvironment to drive their proliferation (Bruno et al, Oncotarget, 2015). However, overtly proliferating CLL cells were resistant to the cytostatic effects of metformin. Since metformin switched the energetic metabolism of activated, not yet proliferating, CLL cells from OXPHOS to accelerated glycolysis, in the present study we asked whether combining metformin with glycolysis impairment could inhibit also proliferating CLL cells. Still, CLL cells recovered from a transitory block and rescued in vitro proliferation. What kind of energetic reprogramming was involved in the resistance of proliferating CLL cells to glucose utilization? Recent studies highlight on the role of fatty acid utilization of CLL cells. We asked 1) whether inhibitors of lipid metabolism could impair proliferation of in vitro stimulated CLL cells; 2) whether impairing glucose energetic pathways could act synergistically with beta oxidation inhibitors.We found that inhibitors of critical steps of fatty acid metabolisms, such as carnitine-palmitoyl transferase 1A (CPT1A) -rate-limiting enzyme for fatty acid import into mitochondria- or Peroxisome Proliferator-Activated Receptor (PPAR)-alpha -regulator of beta-oxidation- administered at clinically achievable doses, were ineffective on quiescent CLL cells and on CLL cells stimulated by the microenvironment during the first stages of activation. Conversely, remarkable susceptibility to undergo apoptosis was observed at later stages of cell activation and during overt proliferation. Synergism with impairment of other energetic pathways occurred depending on the stage of activation of the in vitro stimulated CLL cells.The results suggest that energetic metabolic pathways could be relevant targets for CLL treatment, provided that the complex metabolic reprogramming network during the transition of leukemic cells from quiescence to proliferation, and back, are clearly elucidated. This work was supported by grants from AIRC IG15426.

Interleukin-15 enhances rituximab-dependent cytotoxicity against chronic lymphocytic leukemia cells and overcomes transforming growth factor beta-mediated immunosuppression

Microenvironmental Stromal Cells Rescue CLL Cells from Apoptosis Via Hypoxia That Can be Targeted Therapeutically

Deep Profiling of Chronic Lymphocytic Leukaemia (CLL) and Healthy Immune Cells By Mass Cytometry Resolves Impacts of Venetoclax Pressure

e14552 Background: Transduction of chronic lymphocytic leukemia (CLL) cells with a replication-defective adenovirus (Ad) encoding recombinant CD154 (Ad-ISF35) induces expression of death receptors and Bid via a P53-independent pathway involving induction of P73. Induction of P73 significantly enhances the sensitivity of P53-defective CLL cells to “P53-dependent” drugs, such as Fludarabine (F-ara-A). Patients with P53-defective CLL who received iv infusions of autologous Ad-ISF35-transduced CLL cells were observed to achieve complete remissions (CR) with subsequent treatment using F-ara-A based treatment regimens, suggesting Ad-ISF35 could sensitize P53-defective CLL to chemotherapy. Methods: We examined patients with drug-resistant and/or P53-defective CLL before and after iv infusions of autologous Ad-ISF35-transduced CLL cells who were enrolled in a phase I study examining whether such treatment could sensitize patients to a truncated fludarabine, cyclophosphamide and rituximab (FCR) regimen. We examined CLL cells for sensitivity to F-ara-A in vitro, expression of CD95, DR5, Bid, and P73 and correlated these with the response to treatment in vivo. Results: P53-defective CLL cells were resistant to F-ara-A induced apoptosis with IC50 > 10μM prior to treatment. CLL cells collected from patients≥24 hours after IV infusion of autologous Ad-ISF35-trasduced CLL cells became sensitive to the cytotoxic effects of F-ara-A, with IC50 0.3–1 μM. Enhanced sensitivity to F-ara-A was associated with induced expression of Bid, DR5, CD95, and P73 by circulating CLL cells, an effect lasting≥2 weeks following iv infusion. Consistent with this, we observed complete resolution in lymphocytosis, lymphadenopathy and splenomegaly following 1 cycle of FCR administered 2 weeks after 3 biweekly infusions of Ad-ISF35- transduced CLL cells. Conclusions: IV infusion of autologous Ad-ISF35-transduced CLL cells can induce de novo, systemic expression of death receptors and Bid on bystander CLL cells, which is associated with enhanced sensitivity of P53-defective CLL to the cytotoxic effects of standard chemotherapy [Table: see text]

The Relative Dependency of Chronic Lymphocytic Leukemia (CLL) Cells on Nurselike Cells for in Vitro Survival Is Associated with Overall Survival in Previously Untreated CLL Patients

Clonal and Single Cell Dynamics of Resistance to Graft-Versus-Leukemia (GvL) in Chronic Lymphocytic Leukemia (CLL)

VSV Oncolysis in Combination With the BCL-2 Inhibitor Obatoclax Overcomes Apoptosis Resistance in Chronic Lymphocytic Leukemia

Tumor Heterogeneity-Based Sscr-Score Predicts Prognosis and Reveals Mechanism of SORL1 in Restraining CLL Progression

Ibrutinib Disrupts the Metabolic Program of CLL Cells in-Vivo

The prolonged life span of chronic lymphocytic leukemia (CLL) cells in vivo is assumed to depend on the surrounding microenvironment since this biologic feature is lost in vitro. We studied here the molecular interactions between CLL cells and their surrounding stroma to identify factors that help CLL cells to resist apoptosis. Sorted CLL cells from 21 patients were cultured in vitro on allogenous, normal bone marrow stromal cells (BMSCs) in the presence/absence of CD40 ligand or in culture medium alone. Surface and mRNA expression of interaction molecules, cytokine production, and apoptosis rate was measured by flow cytometric, real-time PCR and standard immunologic assays. The interaction between CLL cells and BMSCs rescued CLL cells from apoptosis. BMSCs co-cultured with CLL cells showed a strong increase in IL-8 and IL-6 secretion and up-regulated the expression of ICAM-1 and CD40 mRNA. The mRNA expression of CXCL12 and VCAM1 remained unchanged. In turn, CLL cells in interaction with BMSCs significantly up-regulated the expression of CD18 and CD49d that are ligands for the critical adhesion molecules on BMSCs. As a validation of the in vitro data, we found a significant higher expression of CD49d on CLL cells in bone marrow aspirates compared to peripheral blood CLL cells in patient samples. Up-regulation of adhesion molecules and their ligands in CLL-BMSCs interaction along with the increased cytokine production of BMSCs indicate a strong effect of CLL cells on BMSCs in favor of their apoptosis resistance.