Showing papers by "Jerome Tamburini published in 2015"

Pim kinases modulate resistance to FLT3 tyrosine kinase inhibitors in FLT3-ITD acute myeloid leukemia

Abstract: Fms-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) is frequently detected in acute myeloid leukemia (AML) patients and is associated with a dismal long-term prognosis. FLT3 tyrosine kinase inhibitors provide short-term disease control, but relapse invariably occurs within months. Pim protein kinases are oncogenic FLT3-ITD targets expressed in AML cells. We show that increased Pim kinase expression is found in relapse samples from AML patients treated with FLT3 inhibitors. Ectopic Pim-2 expression induces resistance to FLT3 inhibition in both FLT3-ITD–induced myeloproliferative neoplasm and AML models in mice. Strikingly, we found that Pim kinases govern FLT3-ITD signaling and that their pharmacological or genetic inhibition restores cell sensitivity to FLT3 inhibitors. Finally, dual inhibition of FLT3 and Pim kinases eradicates FLT3-ITD+ cells including primary AML cells. Concomitant Pim and FLT3 inhibition represents a promising new avenue for AML therapy.

Antileukemic Activity of 2-Deoxy-d-Glucose through Inhibition of N-Linked Glycosylation in Acute Myeloid Leukemia with FLT3-ITD or c-KIT Mutations

Abstract: We assessed the antileukemic activity of 2-deoxy-d-glucose (2-DG) through the modulation of expression of receptor tyrosine kinases (RTK) commonly mutated in acute myeloid leukemia (AML). We used human leukemic cell lines cells, both in vitro and in vivo, as well as leukemic samples from AML patients to demonstrate the role of 2-DG in tumor cell growth inhibition. 2-DG, through N-linked glycosylation inhibition, affected the cell-surface expression and cellular signaling of both FTL3-ITD and mutated c-KIT and induced apoptotic cell death. Leukemic cells harboring these mutated RTKs (MV4-11, MOLM-14, Kasumi-1, and TF-1 c-KIT D816V) were the most sensitive to 2-DG treatment in vitro as compared with nonmutated cells. 2-DG activity was also demonstrated in leukemic cells harboring FLT3-TKD mutations resistant to the tyrosine kinase inhibitor (TKI) quizartinib. Moreover, the antileukemic activity of 2-DG was particularly marked in c-KIT-mutated cell lines and cell samples from core binding factor-AML patients. In these cells, 2-DG inhibited the cell-surface expression of c-KIT, abrogated STAT3 and MAPK-ERK pathways, and strongly downregulated the expression of the receptor resulting in a strong in vivo effect in NOD/SCID mice xenografted with Kasumi-1 cells. Finally, we showed that 2-DG decreases Mcl-1 protein expression in AML cells and induces sensitization to both the BH3 mimetic inhibitor of Bcl-xL, Bcl-2 and Bcl-w, ABT-737, and cytarabine. In conclusion, 2-DG displays a significant antileukemic activity in AML with FLT3-ITD or KIT mutations, opening a new therapeutic window in a subset of AML with mutated RTKs.

Control of Pim2 kinase stability and expression in transformed human haematopoietic cells

Abstract: The oncogenic Pim2 kinase is overexpressed in several haematological malignancies, such as multiple myeloma and acute myeloid leukaemia (AML), and constitutes a strong therapeutic target candidate. Like other Pim kinases, Pim2 is constitutively active and is believed to be essentially regulated through its accumulation. We show that in leukaemic cells, the three Pim2 isoforms have dramatically short half-lives although the longer isoform is significantly more stable than the shorter isoforms. All isoforms present a cytoplasmic localization and their degradation was neither modified by broad-spectrum kinase or phosphatase inhibitors such as staurosporine or okadaic acid nor by specific inhibition of several intracellular signalling pathways including Erk, Akt and mTORC1. Pim2 degradation was inhibited by proteasome inhibitors but Pim2 ubiquitination was not detected even by blocking both proteasome activity and protein de-ubiquitinases (DUBs). Moreover, Pyr41, an ubiquitin-activating enzyme (E1) inhibitor, did not stabilize Pim2, strongly suggesting that Pim2 was degraded by the proteasome without ubiquitination. In agreement, we observed that purified 20S proteasome particles could degrade Pim2 molecule in vitro. Pim2 mRNA accumulation in UT7 cells was controlled by erythropoietin (Epo) through STAT5 transcription factors. In contrast, the translation of Pim2 mRNA was not regulated by mTORC1. Overall, our results suggest that Pim2 is only controlled by its mRNA accumulation level. Catalytically active Pim2 accumulated in proteasome inhibitor-treated myeloma cells. We show that Pim2 inhibitors and proteasome inhibitors, such as bortezomib, have additive effects to inhibit the growth of myeloma cells, suggesting that Pim2 could be an interesting target for the treatment of multiple myeloma.

CDC25A governs proliferation and differentiation of FLT3-ITD acute myeloid leukemia.

Abstract: We investigated cell cycle regulation in acute myeloid leukemia cells expressing the FLT3-ITD mutated tyrosine kinase receptor, an underexplored field in this disease. Upon FLT3 inhibition, CDC25A mRNA and protein were rapidly down-regulated, while levels of other cell cycle proteins remained unchanged. This regulation was dependent on STAT5, arguing for FLT3-ITD-dependent transcriptional regulation of CDC25A. CDC25 inhibitors triggered proliferation arrest and cell death of FLT3-ITD as well as FLT3-ITD/TKD AC-220 resistant cells, but not of FLT3-wt cells. Consistently, RNA interference-mediated knock-down of CDC25A reduced the proliferation of FLT3-ITD cell lines. Finally, the clonogenic capacity of primary FLT3-ITD AML cells was reduced by the CDC25 inhibitor IRC-083864, while FLT3-wt AML and normal CD34+ myeloid cells were unaffected. In good agreement, in a cohort of 100 samples from AML patients with intermediate-risk cytogenetics, high levels of CDC25A mRNA were predictive of higher clonogenic potential in FLT3-ITD+ samples, not in FLT3-wt ones.Importantly, pharmacological inhibition as well as RNA interference-mediated knock-down of CDC25A also induced monocytic differentiation of FLT3-ITD positive cells, as judged by cell surface markers expression, morphological modifications, and C/EBPα phosphorylation. CDC25 inhibition also re-induced monocytic differentiation in primary AML blasts carrying the FLT3-ITD mutation, but not in blasts expressing wild type FLT3. Altogether, these data identify CDC25A as an early cell cycle transducer of FLT3-ITD oncogenic signaling, and as a promising target to inhibit proliferation and re-induce differentiation of FLT3-ITD AML cells.

Rituximab therapy for hairy cell leukemia: a retrospective study of 41 cases

Abstract: The purine analogs (PAs) cladribine and pentostatin have transformed the prognosis of hairy cell leukemia (HCL). However, some patients still relapse after PAs, or fail to reach an optimal response, and new agents are needed to further improve treatment outcome. We retrospectively studied 41 HCL patients from 10 centers in France and Belgium, who received 49 treatment courses with the anti-CD20 monoclonal antibody rituximab. Most of the patients were treated at relapse (84 % of cases) and rituximab was combined to a PA in 41 % of cases. Overall, response rate is 90 % including 71 % complete hematologic responses (CHRs). Frontline treatment, combination therapy, and absolute neutrophil count were associated with response in multivariate analysis. Three-year relapse-free and overall survivals are 68 and 90 %, respectively. When combined to a PA, rituximab yields a 100 % response rate, even beyond frontline therapy. In contrast, response rate is only 82 % (59 % CHR) when rituximab is used alone. In this latter setting, relapse rate is 56 % and median time to relapse is 17.5 months. All eight patients who were treated two times with the antibody responded again to re-treatment. We confirm the high efficacy of the combination rituximab + PA. However, when rituximab is used as monotherapy, response rate is lower and the high relapse rate is a concern. Prospective clinical trials are needed to confirm the superiority of the combination rituximab + PA over PA alone, both as frontline therapy and at relapse.

MB4-2 breakpoint in MMSET combined with del(17p) defines a subset of t(4;14) multiple myeloma with very poor prognosis.

Abstract: Multiple myeloma (MM) is a clonal plasma cell disorder, which remains incurable. The t(4;14) translocation is present in 15% of patients with symptomatic disease and, despite recent therapeutic improvements such as bortezomib treatment, still indicates a poor prognosis.[1][1],[2][2] However, t(4;14

PET2‐driven de‐escalation therapy in 64 high‐risk Hodgkin Lymphoma patients treated with escalated BEACOPP

Abstract: Dang, C.V. (2012) MYC on the path to cancer. Cell, 149, 22–35. Dawson, M.A., Kouzarides, T. & Huntly, B.J. (2012) Targeting epigenetic readers in cancer. New England Journal of Medicine, 367, 647–657. Delmore, J.E., Issa, G.C., Lemieux, M.E., Rahl, P.B., Shi, J., Jacobs, H.M., Kastritis, E., Gilpatrick, T., Paranal, R.M., Qi, J., Chesi, M., Schinzel, A.C., McKeown, M.R., Heffernan, T.P., Vakoc, C.R., Bergsagel, P.L., Ghobrial, I.M., Richardson, P.G., Young, R.A., Hahn, W.C., Anderson, K.C., Kung, A.L., Bradner, J.E. & Mitsiades, C.S. (2011) BET bromodomain inhibition as a therapeutic strategy to target c-Myc. Cell, 146, 904–917. Faber, A.C., Ebi, H., Costa, C. & Engelman, J.A. (2012) Apoptosis in targeted therapy responses: the role of BIM. Advances in Pharmacology, 65, 519–542. Fruman, D.A. & Rommel, C. (2014) PI3K and cancer: lessons, challenges and opportunities. Nature Reviews Drug Discovery, 13, 140–156. Klempner, S.J., Myers, A.P. & Cantley, L.C. (2013) What a tangled web we weave: emerging resistance mechanisms to inhibition of the phosphoinositide 3-kinase pathway. Cancer Discovery, 3, 1345–1354. Loven, J., Hoke, H.A., Lin, C.Y., Lau, A., Orlando, D.A., Vakoc, C.R., Bradner, J.E., Lee, T.I. & Young, R.A. (2013) Selective inhibition of tumor oncogenes by disruption of super-enhancers. Cell, 153, 320–334. Meja, K., Stengel, C., Sellar, R., Huszar, D., Davies, B.R., Gale, R.E., Linch, D.C. & Khwaja, A. (2014) PIM and AKT kinase inhibitors show synergistic cytotoxicity in acute myeloid leukaemia that is associated with convergence on mTOR and MCL1 pathways. British Journal of Haematology, 167, 69–79. Shepherd, C., Banerjee, L., Cheung, C.W., Mansour, M.R., Jenkinson, S., Gale, R.E. & Khwaja, A. (2013) PI3K/mTOR inhibition upregulates NOTCH-MYC signalling leading to an impaired cytotoxic response. Leukemia, 27, 650–660. Zuber, J., Shi, J., Wang, E., Rappaport, A.R., Herrmann, H., Sison, E.A., Magoon, D., Qi, J., Blatt, K., Wunderlich, M., Taylor, M.J., Johns, C., Chicas, A., Mulloy, J.C., Kogan, S.C., Brown, P., Valent, P., Bradner, J.E., Lowe, S.W. & Vakoc, C.R. (2011) RNAi screen identifies Brd4 as a therapeutic target in acute myeloid leukaemia. Nature, 478, 524–528.

Hemophagocytic Lymphohistiocytosis Due to Acute Myeloid Leukemia Relapse: A Very Unusual Association

Abstract: Hemophagocytic lymphohistiocytosis (HLH) diagnosed in the course of acute myeloid leukemia (AML) is generally triggered by treatment-induced infections. AML-induced HLH is a very rare situation for which no diagnostic or therapeutic guidelines are available. We report the occurrence of HLH in an AML5 post-transplant relapse. In our case, the absence of detectable pathogen and the parallel evolution between HLH and leukemia burden suggested a direct link between AML and HLH. We suggest that the diagnostic of AML-related HLH should be promptly considered in front of unexplained fever, cytopenia, liver dysfunction or neurological symptoms as therapeutic intervention is urgent in this life-threatening situation.