Non-Hodgkin lymphomas (NHL) represent the most common hematologic malignancies. Patient-derived xenografts (PDXs) are used for various aspects of translational research including preclinical in vivo validation of experimental treatment approaches. While it was repeatedly demonstrated that PDXs keep majority of somatic mutations with the primary lymphoma samples, from which they were derived, the composition of PDX tumor microenvironment (TME) has not been extensively studied. We carried out a comparative genetic and histopathological study of 15 PDX models derived from patients with various types of NHL including diffuse large B-cell lymphoma (DLBCL; n = 7), Burkitt lymphoma (BL; n = 1), mantle cell lymphoma (MCL; n = 2), and peripheral T-cell lymphomas (PTCL; n = 5). Whole exome sequencing (WES) of the PDXs and primary lymphoma cells was implemented in 13 out of 15 cases with available DNA samples. Standard immunohistochemistry (IHC) was used to analyze the composition of PDX TME. WES data confirmed that PDXs maintained the genetic heterogeneity with the original primary lymphoma cells. In contrast, IHC analysis revealed the following recurrently observed alterations in the composition of PDX tumors: more blastoid lymphoma cell morphology, increased proliferation rate, lack of non-malignant cellular components including T cells and (human or murine) macrophages, and significantly lower intratumoral microvessel density and microvessel area composed of murine vessels. In addition, PDX tumors derived from T-NHL displayed additional differences compared to the primary lymphoma samples including markedly lower desmoplasia (i.e., the extent of both reticular and collagen fibrosis), loss of expression of cytotoxic granules (i.e., perforin, TIA, granzyme B), or loss of expression of T-cell specific antigens (i.e., CD3, CD4, CD8). Our data suggest that despite keeping the same genetic profiles, PDX models of aggressive NHL do not recapitulate the microenvironmental heterogeneity of the original lymphomas. These findings have implications on the relevance of PDX models in the context of preclinical research.

• MeSH
• Lymphoma, Large B-Cell, Diffuse * MeSH
• Adult MeSH
• Heterografts MeSH
• Humans MeSH
• Disease Models, Animal MeSH
• Mice MeSH
• Tumor Microenvironment MeSH
• Antineoplastic Agents * MeSH
• Animals MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Antineoplastic Agents * MeSH

Non-Hodgkin lymphomas (NHL) are lymphoid tumors that arise by a complex process of malignant transformation of mature lymphocytes during various stages of differentiation. The WHO classification of NHL recognizes more than 90 nosological units with peculiar pathophysiology and prognosis. Since the end of the 20th century, our increasing knowledge of the molecular biology of lymphoma subtypes led to the identification of novel druggable targets and subsequent testing and clinical approval of novel anti-lymphoma agents, which translated into significant improvement of patients' outcome. Despite immense progress, our effort to control or even eradicate malignant lymphoma clones has been frequently hampered by the development of drug resistance with ensuing unmet medical need to cope with relapsed or treatment-refractory disease. A better understanding of the molecular mechanisms that underlie inherent or acquired drug resistance might lead to the design of more effective front-line treatment algorithms based on reliable predictive markers or personalized salvage therapy, tailored to overcome resistant clones, by targeting weak spots of lymphoma cells resistant to previous line(s) of therapy. This review focuses on the history and recent advances in our understanding of molecular mechanisms of resistance to genotoxic and targeted agents used in clinical practice for the therapy of NHL.

• Keywords
• chemotherapy, drug resistance, non-Hodgkin lymphomas, targeted agents,
• MeSH
• Drug Resistance, Neoplasm * MeSH
• Precision Medicine MeSH
• Humans MeSH
• Biomarkers, Tumor metabolism   MeSH
• Lymphoma, Non-Hodgkin * classification   metabolism   pathology   therapy   MeSH
• Antineoplastic Agents adverse effects   therapeutic use   MeSH
• Salvage Therapy MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Biomarkers, Tumor MeSH
• Antineoplastic Agents MeSH

Chronic myeloid leukemia (CML) therapy has markedly improved patient prognosis after introduction of imatinib mesylate for clinical use. However, a subset of patients develops resistance to imatinib and other tyrosine kinase inhibitors (TKIs), mainly due to point mutations in the region encoding the kinase domain of the fused BCR-ABL oncogene. To identify potential therapeutic targets in imatinib‑resistant CML cells, we derived imatinib-resistant CML-T1 human cell line clone (CML-T1/IR) by prolonged exposure to imatinib in growth media. Mutational analysis revealed that the Y235H mutation in BCR-ABL is probably the main cause of CML-T1/IR resistance to imatinib. To identify alternative therapeutic targets for selective elimination of imatinib-resistant cells, we compared the proteome profiles of CML-T1 and CML-T1/IR cells using 2-DE-MS. We identified eight differentially expressed proteins, with strongly upregulated Na+/H+ exchanger regulatory factor 1 (NHERF1) in the resistant cells, suggesting that this protein may influence cytosolic pH, Ca2+ concentration or signaling pathways such as Wnt in CML-T1/IR cells. We tested several compounds including drugs in clinical use that interfere with the aforementioned processes and tested their relative toxicity to CML-T1 and CML-T1/IR cells. Calcium channel blockers, calcium signaling antagonists and modulators of calcium homeostasis, namely thapsigargin, ionomycin, verapamil, carboxyamidotriazole and immunosuppressive drugs cyclosporine A and tacrolimus (FK-506) were selectively toxic to CML-T1/IR cells. The putative cellular targets of these compounds in CML-T1/IR cells are postulated in this study. We propose that Ca2+ homeostasis can be a potential therapeutic target in CML cells resistant to TKIs. We demonstrate that a proteomic approach may be used to characterize a TKI-resistant population of CML cells enabling future individualized treatment options for patients.

• MeSH
• Fusion Proteins, bcr-abl metabolism   MeSH
• Drug Resistance, Neoplasm drug effects   MeSH
• Leukemia, Myelogenous, Chronic, BCR-ABL Positive drug therapy   metabolism   MeSH
• Homeostasis drug effects   MeSH
• Imatinib Mesylate pharmacology   MeSH
• Protein Kinase Inhibitors pharmacology   MeSH
• Humans MeSH
• Mutation drug effects   MeSH
• Cell Line, Tumor MeSH
• Proteome metabolism   MeSH
• Proteomics methods   MeSH
• Signal Transduction drug effects   MeSH
• Calcium metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Fusion Proteins, bcr-abl MeSH
• Imatinib Mesylate MeSH
• Protein Kinase Inhibitors MeSH
• Proteome MeSH
• Calcium MeSH

Tumor immunotherapy based on the use of chimeric antigen receptor modified T cells (CAR T cells) is a promising approach for the treatment of refractory hematological malignancies. However, a robust response mediated by CAR T cells is observed only in a minority of patients and the expansion and persistence of CAR T cells in vivo is mostly unpredictable.Lenalidomide (LEN) is an immunomodulatory drug currently approved for the treatment of multiple myeloma (MM) and mantle cell lymphoma, while it is clinically tested in the therapy of diffuse large B-cell lymphoma of activated B cell immunophenotype. LEN was shown to increase antitumor immune responses at least partially by modulating the activity of E3 ubiquitin ligase Cereblon, which leads to increased ubiquitinylation of Ikaros and Aiolos transcription factors, which in turn results in changed expression of various receptors on the surface of tumor cells. In order to enhance the effectiveness of CAR-based immunotherapy, we assessed the anti-lymphoma efficacy of LEN in combination with CAR19 T cells or CAR20 T cells in vitro and in vivo using various murine models of aggressive B-cell non-Hodgkin lymphomas (B-NHL).Immunodeficient NSG mice were transplanted with various human B-NHL cells followed by treatment with CAR19 or CAR20 T cells with or without LEN. Next, CAR19 T cells were subjected to series of tests in vitro to evaluate their response and signaling capacity following recognition of B cell in the presence or absence of LEN.Our data shows that LEN significantly enhances antitumor functions of CAR19 and CAR20 T cells in vivo. Additionally, it enhances production of interferon gamma by CAR19 T cells and augments cell signaling via CAR19 protein in T cells in vitro. Our data further suggests that LEN works through direct effects on T cells but not on B-NHL cells. The biochemical events underlying this costimulatory effect of LEN are currently being investigated. In summary, our data supports the use of LEN for augmentation of CAR-based immunotherapy in the clinical grounds.

• Keywords
• Chimeric antigenic receptor, T cells, lenalidomide, lymphoma, tumor immunotherapy,
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Mantle cell lymphoma (MCL) is characterized by an aggressive clinical course and inevitable development of refractory disease, stressing the need to develop alternative therapeutic strategies. To this end, we evaluated pevonedistat (MLN4924), a novel potent and selective NEDD8-activating enzyme inhibitor in a panel of MCL cell lines, primary MCL tumor cells, and 2 distinct murine models of human MCL. Pevonedistat exposure resulted in a dose-, time-, and caspase-dependent cell death in the majority of the MCL cell lines and primary tumor cells tested. Of interest, in the MCL cell lines with lower half-maximal inhibitory concentration (0.1-0.5 μM), pevonedistat induced G1-phase cell cycle arrest, downregulation of Bcl-xL levels, decreased nuclear factor (NF)-κB activity, and apoptosis. In addition, pevonedistat exhibited additive/synergistic effects when combined with cytarabine, bendamustine, or rituximab. In vivo, as a single agent, pevonedistat prolonged the survival of 2 MCL-bearing mouse models when compared with controls. Pevonedistat in combination with rituximab led to improved survival compared with rituximab or pevonedistat monotherapy. Our data suggest that pevonedistat has significant activity in MCL preclinical models, possibly related to effects on NF-κB activity, Bcl-xL downregulation, and G1 cell cycle arrest. Our findings support further investigation of pevonedistat with or without rituximab in the treatment of MCL.

• MeSH
• Apoptosis drug effects   MeSH
• Cyclopentanes pharmacology   therapeutic use   MeSH
• Enzyme Inhibitors pharmacology   therapeutic use   MeSH
• Caspases metabolism   MeSH
• Small Molecule Libraries pharmacology   therapeutic use   MeSH
• Cell Cycle Checkpoints drug effects   MeSH
• Humans MeSH
• Lymphoma, Mantle-Cell drug therapy   genetics   pathology   MeSH
• Mice, SCID MeSH
• Cell Line, Tumor MeSH
• NF-kappa B metabolism   MeSH
• NEDD8 Protein MeSH
• Antineoplastic Agents pharmacology   therapeutic use   MeSH
• Proto-Oncogene Proteins c-bcl-2 metabolism   MeSH
• Pyrimidines pharmacology   therapeutic use   MeSH
• Gene Expression Regulation, Neoplastic drug effects   MeSH
• Rituximab pharmacology   therapeutic use   MeSH
• Cell Separation MeSH
• Gene Expression Profiling MeSH
• Ubiquitins antagonists & inhibitors   metabolism   MeSH
• Cell Survival drug effects   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, N.I.H., Extramural MeSH
• Names of Substances
• Cyclopentanes MeSH
• Enzyme Inhibitors MeSH
• Caspases MeSH
• Small Molecule Libraries MeSH
• NEDD8 protein, human MeSH Browser
• NF-kappa B MeSH
• pevonedistat MeSH Browser
• NEDD8 Protein MeSH
• Antineoplastic Agents MeSH
• Proto-Oncogene Proteins c-bcl-2 MeSH
• Pyrimidines MeSH
• Rituximab MeSH
• Ubiquitins MeSH

BACKGROUND: Mantle cell lymphoma (MCL) is an aggressive type of B-cell non-Hodgkin lymphoma associated with poor prognosis. Implementation of high-dose cytarabine (araC) into induction therapy became standard-of-care for all newly diagnosed younger MCL patients. However, many patients relapse even after araC-based regimen. Molecular mechanisms responsible for araC resistance in MCL are unknown and optimal treatment strategy for relapsed/refractory MCL patients remains elusive. METHODS: Five araC-resistant (R) clones were derived by long-term culture of five MCL cell lines (CTRL) with increasing doses of araC up to 50 microM. Illumina BeadChip and 2-DE proteomic analysis were used to identify gene and protein expression changes associated with araC resistance in MCL. In vitro cytotoxicity assays and experimental therapy of MCL xenografts in immunodeficient mice were used to analyze their relative responsiveness to a set of clinically used anti-MCL drugs. Primary MCL samples were obtained from patients at diagnosis and after failure of araC-based therapies. RESULTS: Marked downregulation of deoxycytidine-kinase (DCK) mRNA and protein expression was identified as the single most important molecular event associated with araC-resistance in all tested MCL cell lines and in 50% primary MCL samples. All R clones were highly (20-1000x) cross-resistant to all tested nucleoside analogs including gemcitabine, fludarabine and cladribine. In vitro sensitivity of R clones to other classes of clinically used anti-MCL agents including genotoxic drugs (cisplatin, doxorubicin, bendamustine) and targeted agents (bortezomib, temsirolimus, rituximab) remained unaffected, or was even increased (ibrutinib). Experimental therapy of immunodeficient mice confirmed the anticipated loss of anti-tumor activity (as determined by overall survival) of the nucleoside analogs gemcitabine and fludarabine in mice transplanted with R clone compared to mice transplanted with CTRL cells, while the anti-tumor activity of cisplatin, temsirolimus, bortezomib, bendamustine, cyclophosphamide and rituximab remained comparable between the two cohorts. CONCLUSIONS: Acquired resistance of MCL cells to araC is associated with downregulation of DCK, enzyme of the nucleotide salvage pathway responsible for the first phosphorylation (=activation) of most nucleoside analogs used in anti-cancer therapy. The data suggest that nucleoside analogs should not be used in the therapy of MCL patients, who relapse after failure of araC-based therapies.

• MeSH
• Electrophoresis, Gel, Two-Dimensional MeSH
• Clone Cells MeSH
• Drug Resistance, Neoplasm drug effects   MeSH
• Cytarabine pharmacology   MeSH
• Deoxycytidine analogs & derivatives   pharmacology   MeSH
• Deoxycytidine Kinase metabolism   MeSH
• Down-Regulation drug effects   MeSH
• Gemcitabine MeSH
• Mass Spectrometry MeSH
• Cladribine pharmacology   MeSH
• Humans MeSH
• Lymphoma, Mantle-Cell drug therapy   enzymology   genetics   MeSH
• Antibodies, Monoclonal, Murine-Derived pharmacology   therapeutic use   MeSH
• Mice MeSH
• Cell Line, Tumor MeSH
• Proteomics MeSH
• Antineoplastic Agents pharmacology   therapeutic use   MeSH
• Gene Expression Regulation, Neoplastic drug effects   MeSH
• Rituximab MeSH
• Gene Expression Profiling MeSH
• Vidarabine analogs & derivatives   pharmacology   MeSH
• Blotting, Western MeSH
• Xenograft Model Antitumor Assays MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Cytarabine MeSH
• Deoxycytidine MeSH
• Deoxycytidine Kinase MeSH
• fludarabine MeSH Browser
• Gemcitabine MeSH
• Cladribine MeSH
• Antibodies, Monoclonal, Murine-Derived MeSH
• Antineoplastic Agents MeSH
• Rituximab MeSH
• Vidarabine MeSH