High-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements, mostly known as double-hit lymphoma (DHL), is a rare entity characterized by morphologic and molecular features between Burkitt lymphoma and the clinically manageable diffuse large B-cell lymphoma (DLBCL). DHL patients usually undergo a rapidly progressing clinical course associated with resistance to standard chemo-immunotherapy. As a consequence, the prognosis of this entity is particularly poor with a median overall survival inferior to 1 year. ABT-199 (venetoclax) is a potent and selective small-molecule antagonist of BCL-2 recently approved for the treatment of a specific subtype of lymphoid neoplasm. In this study, we demonstrate that single-agent ABT-199 efficiently displaces BAX from BCL-2 complexes but fails to maintain a significant antitumor activity over time in most MYC+/BCL2+DHL cell lines and primary cultures, as well as in a xenograft mouse model of the disease. We further identify the accumulation of the BCL2-like protein BFL-1 to be a major mechanism involved in acquired resistance to ABT-199. Noteworthy, this phenomenon can be counteracted by the BET bromodomain inhibitor CPI203, since gene expression profiling identifies BCL2A1, the BFL-1 coding gene, as one of the top apoptosis-related gene modulated by this compound. Upon CPI203 treatment, simultaneous downregulation of MYC and BFL-1 further overcomes resistance to ABT-199 both in vitro and in vivo, engaging synergistic caspase-mediated apoptosis in DHL cultures and tumor xenografts. Together, these findings highlight the relevance of BFL-1 in DH lymphoma-associated drug resistance and support the combined use of a BCL-2 antagonist and a BET inhibitor as a promising therapeutic strategy for patients with aggressive DHL.

The tumourigenic capacity of ZEB1 depends on its inhibition of cancer cell senescence through the activation of a herein identified new molecular pathway. These results set ZEB1 as a potential target in therapeutic strategies aimed at inducing senescence.

Mantle cell lymphoma (MCL) is a hematologic neoplasm characterised by the t(11;14)(q13;q32) translocation leading to aberrant cyclin D1 expression. The cell functions of cyclin D1 depend on its partners and/or subcellular distribution, resulting in different oncogenic properties. We observed the accumulation of cyclin D1 in the cytoplasm of a subset of MCL cell lines and primary cells. In primary cells, this cytoplasmic distribution was correlated with a more frequent blastoid phenotype. We performed immunoprecipitation assays and mass spectrometry on enriched cytosolic fractions from two cell lines. The cyclin D1 interactome was found to include several factors involved in adhesion, migration and invasion. We found that the accumulation of cyclin D1 in the cytoplasm was associated with higher levels of migration and invasiveness. We also showed that MCL cells with high cytoplasmic levels of cyclin D1 engrafted more rapidly into the bone marrow, spleen, and brain in immunodeficient mice. Both migration and invasion processes, both in vivo and in vitro, were counteracted by the exportin 1 inhibitor KPT-330, which retains cyclin D1 in the nucleus. Our data reveal a role of cytoplasmic cyclin D1 in the control of MCL cell migration and invasion, and as a true operator of MCL pathogenesis.

Constitutive activation of the chemokine receptor CXCR4 has been associated with tumor progression, invasion, and chemotherapy resistance in different cancer subtypes. Although the CXCR4 pathway has recently been suggested as an adverse prognostic marker in diffuse large B-cell lymphoma, its biological relevance in this disease remains underexplored. In a homogeneous cohort of 52 patient biopsies, an antibody-based cytokine array showed that tissue levels of CXCL12 correlated with high microvessel density and bone marrow involvement at diagnosis, supporting a role for CXCL12-CXCR4 axis in disease progression. We then identified the tetra-amine IQS-01.01RS as a potent inverse agonist of the receptor, preventing CXCL12-mediated chemotaxis and triggering apoptosis in a panel of 18 cell lines and primary cultures, with superior mobilizing properties in vivo than standard agent. IQS-01.01RS activity was associated with downregulation of p-AKT, p-ERK1/2 and destabilization of MYC, allowing to a synergistic interaction with the bromodomain and extra-terminal domain inhibitor, CPI203. In a xenotransplant model of diffuse large B-cell lymphoma, IQS-01.01RS/CPI203 combination decreased tumor burden through MYC and p-AKT downregulation, and enhanced apoptosis induction. Thus, our results point out an emerging role of CXCL12-CXCR4 in the pathogenesis of diffuse large B-cell lymphoma and support the simultaneous targeting of CXCR4 and bromodomain proteins as a promising, rationale-based strategy for this disease.

BackgroundPharmacological inhibition of B cell receptor (BCR) signaling has recently emerged as an effective approach in a wide range of B lymphoid neoplasms. However, despite promising clinical activity of the first Bruton’s kinase (Btk) and spleen tyrosine kinase (Syk) inhibitors, a small fraction of patients tend to develop progressive disease after initial response to these agents.MethodsWe evaluated the antitumor activity of IQS019, a new BCR kinase inhibitor with increased affinity for Btk, Syk, and Lck/Yes novel tyrosine kinase (Lyn), in a set of 34 B lymphoid cell lines and primary cultures, including samples with acquired resistance to the first-in-class Btk inhibitor ibrutinib. Safety and efficacy of the compound were then evaluated in two xenograft mouse models of B cell lymphoma.ResultsIQS019 simultaneously engaged a rapid and dose-dependent de-phosphorylation of both constitutive and IgM-activated Syk, Lyn, and Btk, leading to impaired cell proliferation, reduced CXCL12-dependent cell migration, and induction of caspase-dependent apoptosis. Accordingly, B cell lymphoma-bearing mice receiving IQS019 presented a reduced tumor outgrowth characterized by a decreased mitotic index and a lower infiltration of malignant cells in the spleen, in tight correlation with downregulation of phospho-Syk, phospho-Lyn, and phospho-Btk. More interestingly, IQS019 showed improved efficacy in vitro and in vivo when compared to the first-in-class Btk inhibitor ibrutinib, and was active in cells with acquired resistance to this latest.ConclusionsThese results define IQS019 as a potential drug candidate for a variety of B lymphoid neoplasms, including cases with acquired resistance to current BCR-targeting therapies.Electronic supplementary materialThe online version of this article (doi:10.1186/s13045-017-0447-6) contains supplementary material, which is available to authorized users.

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Imbalances in the composition of BCL2 family proteins contribute to tumourigenesis and therapy resistance of mantle cell lymphoma (MCL), making these proteins attractive therapy targets. We studied the efficiency of dual targeting the NOXA/MCL1 axis by combining fatty acid synthase inhibitors (NOXA stabilization) with the CDK inhibitor Dinaciclib (MCL1 reduction). This combination synergistically induced apoptosis in cell lines and primary MCL cells and led to almost complete inhibition of tumour progression in a mouse model. Apoptosis was NOXA-dependent and correlated with the NOXA/MCL1 ratio, highlighting the importance of the NOXA/MCL1 balance for effective cell death induction in MCL.

Double-hit lymphoma (DHL) is a rare subtype of B-cell lymphoma characterized by MYC and either BCL2 or BCL6 chromosomal rearrangements. DHL cases may have different morphology and are included in the updated 2016 WHO classification as a new category of high grade B-cell lymphoma with rearrangements. DHL patients usually undergo a rapidly progressing clinical course and are poorly responsive to standard chemo-immunotherapy. As a consequence, the prognosis of this entity is particularly poor with a median overall survival of approximately one year. ABT-199 (venetoclax) is a potent and selective small-molecule antagonist of BCL-2 recently approved for the treatment of some lymphoid malignancies. In this study, we demonstrate that single-agent ABT-199 efficiently displaces pro-apoptotic BAX from BCL-2 complexes but fails to maintain a significant antitumor activity over time in most MYC+/BCL2+ DHL cell lines and primary cultures, as well as in a xenograft mouse model of DHL. We further identify the accumulation of the BCL2-like protein, BFL-1, to be a major mechanism involved in acquired resistance to ABT-199. We show this phenomenon to be manageable by the BET bromodomain inhibitor CPI203, since gene expression profiling identifies BCL2A1 as one of the top apoptosis-related gene modulated by the compound. Upon CPI203 treatment, simultaneous downregulation of MYC and BFL-1 at both mRNA and protein levels further overcomes resistance to ABT-199 both in vitro and in vivo, allowing DHL cultures and tumor xenografts to undergo synergistic caspase-mediated apoptosis. Together, these findings highlight the relevance of BFL-1 in DHL-associated drug resistance and support the combined use of BCL-2 antagonist and BET inhibitor as a promising therapeutic strategy in patients with aggressive DHL. Citation Format: Anna Esteve-Arenys, Juan Garcia-Valero, David Gonzalez, Aránzazu Chamorro-Jorganes, Vanina Rodriguez, Ivan Dlouhy, Itziar Salaverria, Elias Campo, Dolors Colomer, Antonio Martinez, Grzegorz Rymkiewicz, Patricia Pérez-Galán, Armando Lopez-Guillermo, Gaël Roué. Pharmacological downregulation of BFL-1 by the BET bromodomain inhibitor CPI203 overcomes ABT-199 resistance in MYC+/BCL2+ double hit lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2161. doi:10.1158/1538-7445.AM2017-2161