Active Akt signaling triggers CLL toward Richter transformation via overactivation of Notch1.

Richter's transformation (RT) is an aggressive lymphoma that occurs upon progression from chronic lymphocytic leukemia (CLL). Transformation has been associated with genetic aberrations in the CLL phase involving TP53, CDKN2A, MYC, and NOTCH1; however, a significant proportion of RT cases lack CLL phase-associated events. Here, we report that high levels of AKT phosphorylation occur both in high-risk CLL patients harboring TP53 and NOTCH1 mutations as well as in patients with RT. Genetic overactivation of Akt in the murine Eµ-TCL1 CLL mouse model resulted in CLL transformation to RT with significantly reduced survival and an aggressive lymphoma phenotype. In the absence of recurrent mutations, we identified a profile of genomic aberrations intermediate between CLL and diffuse large B-cell lymphoma. Multiomics assessment by phosphoproteomic/proteomic and single-cell transcriptomic profiles of this Akt-induced murine RT revealed an S100 protein-defined subcluster of highly aggressive lymphoma cells that developed from CLL cells, through activation of Notch via Notch ligand expressed by T cells. Constitutively active Notch1 similarly induced RT of murine CLL. We identify Akt activation as an initiator of CLL transformation toward aggressive lymphoma by inducing Notch signaling between RT cells and microenvironmental T cells.

Meta-Analysis Reveals Significant Sex Differences in Chronic Lymphocytic Leukemia Progression in the Eµ-TCL1 Transgenic Mouse Model.

The Eµ-TCL1 transgenic mouse model represents the most widely and extensively used animal model for chronic lymphocytic leukemia (CLL). In this report, we performed a meta-analysis of leukemia progression in over 300 individual Eµ-TCL1 transgenic mice and discovered a significantly accelerated disease progression in females compared to males. This difference is also reflected in an aggressive CLL mouse model with additional deletion of Tp53 besides the TCL1 transgene. Moreover, after serial adoptive transplantation of murine CLL cells, female recipients also succumbed to CLL earlier than male recipients. This sex-related disparity in the murine models is markedly contradictory to the human CLL condition. Thus, due to our observation we urge both careful consideration in the experimental design and accurate description of the Eµ-TCL1 transgenic cohorts in future studies.

CD74 is dispensable for development of chronic lymphocytic leukemia in Eµ-TCL1 transgenic mice.

CD74 is a surface protein expressed on immune cells, which acts as receptor for the chemokine macrophage migration inhibitory factor (MIF). Signaling via the MIF/CD74-axis has been reported to be important for the pathogenesis of chronic lymphocytic leukemia (CLL). We wanted to clarify the role of CD74 in MIF-induced signaling/leukemic development. In Eµ-TCL1 transgenic mice, occurrence of the leukemic phenotype was associated with increased surface CD74 expression. Eµ-TCL1+/+Cd74-/- mice showed similar kinetics and clinical features of CLL development as Eµ-TCL1+/+ mice. MIF stimulation of leukemic splenocytes led to AKT activation in a CD74-dependent manner. AKT activation was reduced in Cd74-deficient splenocytes in the presence of the oncogenic TCL1-transgene. Tumor cell apoptosis/proliferation were unaffected in Eµ-TCL1+/+Cd74-/- mice. Our data suggest that the need for active CD74 signaling is overcome in the leukemic context of TCL1-driven CLL, and that CD74 may have a dispensable role for CLL pathogenesis in this model.

LYN Kinase in the Tumor Microenvironment Is Essential for the Progression of Chronic Lymphocytic Leukemia.

Survival of chronic lymphocytic leukemia (CLL) cells strictly depends on the support of an appropriate tumor microenvironment. Here, we demonstrate that LYN kinase is essential for CLL progression. Lyn deficiency results in a significantly reduced CLL burden in vivo. Loss of Lyn within leukemic cells reduces B cell receptor (BCR) signaling including BTK phosphorylation, but surprisingly does not affect leukemic cell expansion. Instead, syngeneic CLL transplantation of CLL cells into Lyn- or Btk-deficient recipients results in a strongly delayed leukemic progression and prolonged survival. Moreover, Lyn deficiency in macrophages hinders nursing functions for CLL cells, which is mediated by direct contact rather than secretion of soluble factors. Taken together, LYN and BTK seem essential for the formation of a microenvironment supporting leukemic growth.

Post-chemotherapy cognitive impairment in patients with B-cell non-Hodgkin lymphoma: a first comprehensive approach to determine cognitive impairments after treatment with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone or rituximab and bendamustine.

To assess the effects of chemoimmunotherapy on post-chemotherapy cognitive impairments (PCCI) in patients with B-cell non-Hodgkin lymphoma (NHL), we used objective and subjective measures of cognitive functions in combination with serum parameters and neuroelectric recordings. Self-perceived status of cognition, fatigue and emotional functioning were reduced in patients (n=30) compared to healthy controls (n=10). Cognitive performance was impaired in patients with NHL compared to controls and a norm sample (n=1179). PCCI was more severe in patients treated with rituximab and bendamustine (BR) than in patients who received R in combination with CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) polychemotherapy (R-CHOP). Individual alpha peak frequency and serum brain-derived neurotrophic factor (BDNF) levels in patients with NHL correlated with accuracy in the objective cognition test. Higher serum interleukin-6 (IL-6) concentrations were associated with higher fatigue levels. Patients with NHL and especially those who were treated with BR were affected by PCCI. BDNF and IL-6 might be involved in the pathogenesis of PCCI and fatigue.

Impact of exercise on pro inflammatory cytokine levels and epigenetic modulations of tumor-competitive lymphocytes in Non-Hodgkin-Lymphoma patients-randomized controlled trial.

INTRODUCTION: Physical activity is associated with decreased cancer (recurrence) risk and a reduction in treatment-specific side effects. Exercise modulates cytokine expression and shows beneficial effects on cancer patients' immune system. We investigated the following: (i) whether Non-Hodgkin-Lymphoma patients have increased serum macrophage migration inhibiting factor (MIF) and Interleukin-6 (IL-6) levels after immunochemotherapy; (ii) whether physical activity influences cytokine serum levels; and (iii) whether serum cytokine levels are associated with histone modifications in tumor-competitive immune cells. METHODS: Thirty patients and 10 healthy controls were randomised into an intervention and a control group. Participants of the intervention group exercised once for 30 min at moderate intensity on a bicycle ergometer. Blood samples were collected twice, before and after the intervention. MIF and IL-6 serum concentrations were detected by ELISA. Natural killer cells and CD8(+) T-lymphocytes were isolated by magnetic labeled cell sorting. Isolated cells were stained and analyzed for global histone acetylation at histone 4, lysine 5 and histone three, lysine 9. RESULTS: Patients showed higher serum MIF and IL-6 baseline levels, and reduced NK-cell histone acetylation, indicating a reduced transcriptional activity of tumor-competitive lymphocytes. Changes in MIF correlated with altered NK-cell histone acetylation, leading to the hypothesis that MIF impacts NK-cells via epigenetic modifications. Further, the exercise intervention was associated with an increase in IL-6 and CD8(+) T-lymphocyte histone acetylation. CONCLUSIONS: We conclude that exercise induces changes in cytokine levels, thereby possibly affecting epigenetic patterns and activity of tumor-competitive lymphocytes.

Sequential chemoimmunotherapy of fludarabine, mitoxantrone, and cyclophosphamide induction followed by alemtuzumab consolidation is effective in T-cell prolymphocytic leukemia.

BACKGROUND: Scarce systematic trial data have prevented uniform therapeutic guidelines for T-cell prolymphocytic leukemia (T-PLL). A central need in this historically refractory tumor is the controlled evaluation of multiagent chemotherapy and its combination with the currently most active single agent, alemtuzumab. METHODS: This prospective multicenter phase 2 trial assessed response, survival, and toxicity of a novel regimen in previously treated (n = 9) and treatment-naive (n = 16) patients with T-PLL. Induction by fludarabine, mitoxantrone, and cyclophosphamide (FMC), for up to 4 cycles, was followed by alemtuzumab (A) consolidation, up to 12 weeks. RESULTS: Of the 25 patients treated with FMC, 21 subsequently received alemtuzumab. Overall response rate to FMC was 68%, comprising 6 complete remissions (all bone-marrow confirmed) and 11 partial remissions. Alemtuzumab consolidation increased the intent-to-treat overall response rate to 92% (12 complete remissions; 11 partial remissions). Median overall survival after FMC-A was 17.1 months and median progression-free survival was 11.9 months. Progression-free survival tended to be shorter for patients with high-level T-cell leukemia 1 oncoprotein expression. Hematologic toxicities were the most frequent grade 3/4 side effects under FMC-A. Exclusively in the 21 alemtuzumab-consolidated patients, 13 cytomegalovirus reactivations were observed; 9 of these 13 represented a clinically relevant infection. CONCLUSIONS: FMC-A is a safe and efficient protocol in T-PLL, which compares favorably to published data.

Delayed development of chronic lymphocytic leukemia in the absence of macrophage migration inhibitory factor.

UNLABELLED: Survival of chronic lymphocytic leukemia (CLL) cells depends on stimuli provided by a suitable microenvironment. The factors and mechanisms providing this growth support for CLL cells are not fully understood. We found that plasma levels of macrophage migration inhibitory factor (MIF), a proinflammatory and immunoregulatory chemokine, were elevated in CLL patients. Therefore, we characterized the functional role of MIF in a CLL mouse model. For this purpose, we crossed Eµ-TCL1 mice with MIF knockout (MIF-/-) mice. The resulting TCL1+/wtMIF/ mice showed a delayed onset of leukemia, reduced splenomegaly and hepatomegaly, and a longer survival than TCL1+/wtMIFwt/wt controls. Immunohistochemical examination of the lymphoid organs showed that the numbers of macrophages were significantly reduced in the spleen and bone marrow of TCL1+/wtMIF/ mice compared with TCL1+/wtMIFwt/wt controls. Mechanistic studies in vitro revealed that the absence of MIF rendered CLL cells more susceptible to apoptosis. Accordingly, incubation with an anti-MIF antibody reduced the survival of CLL cells on a macrophage feeder layer. In addition, the migratory activity of TCL1+/wtMIF/ macrophages was decreased compared with TCL1+/wtMIFwt/wt macrophages. Taken together, our results provide evidence that MIF supports the development of CLL by enhancing the interaction of CLL cells with macrophages. KEY POINTS: Targeted deletion of the gene for macrophage migration inhibitory factor (MIF) delays development of chronic lymphocytic leukemia and prolongs survival in mice. MIF recruits leukemia-associated macrophages to spleen or liver.

A tautomerase-null macrophage migration-inhibitory factor (MIF) gene knock-in mouse model reveals that protein interactions and not enzymatic activity mediate MIF-dependent growth regulation.

Macrophage migration-inhibitory factor (MIF) is an upstream regulator of innate immunity and a potential molecular link between inflammation and cancer. The unusual structural homology between MIF and certain tautomerases, which includes both a conserved substrate-binding pocket and a catalytic N-terminal proline (Pro1), has fueled speculation that an enzymatic reaction underlies MIF's biologic function. To address the functional role of the MIF tautomerase activity in vivo, we created a knock-in mouse in which the endogenous mif gene was replaced by one encoding a tautomerase-null, Pro1-->Gly1 MIF protein (P1G-MIF). While P1G-MIF is completely inactive catalytically, it maintains significant, albeit reduced, binding to its cell surface receptor (CD74) and to the intracellular binding protein JAB1/CSN5. P1G-MIF knock-in mice (mif(P1G/P1G)) and cells derived from these mice show a phenotype in assays of growth control and tumor induction that is intermediate between those of the wild type (mif(+/+)) and complete MIF deficiency (mif(-)(/)(-)). These data provide genetic evidence that MIF's intrinsic tautomerase activity is dispensable for this cytokine's growth-regulatory properties and support a role for the N-terminal region in protein-protein interactions.