In Vitro and In Vivo Anti Lymphoma Effect of GX15-070 in Mantle Cell Lymphoma.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 4756-4756 ◽  
Author(s):  
Gwyn Bebb ◽  
Huong Muzik ◽  
Sophia Nguyen ◽  
Don Morris ◽  
Douglas A. Stewart

Abstract Introduction Mantle cell lymphoma (MCL), an incurable B cell lymphoma, consistently over expresses bcl-2 despite not carrying the t(14;18). The attenuation of apoptosis by bcl-2 is thought to contribute to the malignant process and increase resistance to some cytotoxic agents. We recently demonstrated that GX15-070, a small molecular inhibitor of the BH3 binding groove of bcl-2, has activity against MCL cell lines in vitro. We set out to assess the effect of GX15-070 alone and in combination with Vincristine on the viability of MCL cells in vitro and in vivo. Methods 3 previously characterized bcl-2 over expressing MCL cell lines (JVM-2, Hbl-2, granta) were used. Cells were grown in standard media and exposed to a range of concentrations of GX15-070 with and without Vincristine. Dose-response was assessed by measuring viability at 48 hours using the WST-1 assay. In vivo experiments were conducted on immune deficient mice in which 5×106 cells were injected in the flank then treated IV with GX15-070 (q 2days × 5 doses), Vincristine (q4 days × 3 doses) or both starting 5 days later. Tumours were measured three times weekly. Results All three MCL cell lines over-expressed bcl-2 by western blot. Each MCL cell line showed sensitivity to GX15-070 at a range of concentrations. The addition of GX15-070 to low dose Vincristine (10−6) caused significant growth inhibition of each MCL cell line (see table 1). Discussion Our results demonstrate that using GX15-070 to target bcl-2 is an effective anti neoplastic approach against MCL cell lines in vitro. In addition, our results suggest that combining Vincristine and GX15-070 is a promising strategy in treating MCL. In vivo experiments to confirm this additive activity are still ongoing and will be presented in full. Initial impressions suggest that there is a rationale for the addition of GX15-070 to current cytotoxic regimens used to treat MCL in the setting of clinical trials. Table 1: Effect of Vincristine and GX15-070 on in vitro growth of 3 MCL cell lines Growth as % age of Control Cell Line JVM-2 HBL-2 Granta Vincristine alone (10-6 mg/ml) 92% 48% 89% GX15-070 alone (0.08 uM) 75% 76% 60% Vincristine 10-6 mg/ml and GX15-070 0.08 uM 52% 24% 52%

ESMO Open ◽  
2018 ◽  
Vol 3 (6) ◽  
pp. e000387 ◽  
Author(s):  
Chiara Tarantelli ◽  
Elena Bernasconi ◽  
Eugenio Gaudio ◽  
Luciano Cascione ◽  
Valentina Restelli ◽  
...  

BackgroundThe outcome of patients affected by mantle cell lymphoma (MCL) has improved in recent years, but there is still a need for novel treatment strategies for these patients. Human cancers, including MCL, present recurrent alterations in genes that encode transcription machinery proteins and of proteins involved in regulating chromatin structure, providing the rationale to pharmacologically target epigenetic proteins. The Bromodomain and Extra Terminal domain (BET) family proteins act as transcriptional regulators of key signalling pathways including those sustaining cell viability. Birabresib (MK-8628/OTX015) has shown antitumour activity in different preclinical models and has been the first BET inhibitor to successfully undergo early clinical trials.Materials and methodsThe activity of birabresib as a single agent and in combination, as well as its mechanism of action was studied in MCL cell lines.ResultsBirabresib showed in vitro and in vivo activities, which appeared mediated via downregulation of MYC targets, cell cycle and NFKB pathway genes and were independent of direct downregulation of CCND1. Additionally, the combination of birabresib with other targeted agents (especially pomalidomide, or inhibitors of BTK, mTOR and ATR) was beneficial in MCL cell lines.ConclusionOur data provide the rationale to evaluate birabresib in patients affected by MCL.


2003 ◽  
Vol 77 (3) ◽  
pp. 2134-2146 ◽  
Author(s):  
Vicky M.-H. Sung ◽  
Shigetaka Shimodaira ◽  
Alison L. Doughty ◽  
Gaston R. Picchio ◽  
Huong Can ◽  
...  

ABSTRACT Hepatitis C virus (HCV) is a major cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. Studies of HCV replication and pathogenesis have so far been hampered by the lack of an efficient tissue culture system for propagating HCV in vitro. Although HCV is primarily a hepatotropic virus, an increasing body of evidence suggests that HCV also replicates in extrahepatic tissues in natural infection. In this study, we established a B-cell line (SB) from an HCV-infected non-Hodgkin's B-cell lymphoma. HCV RNA and proteins were detectable by RNase protection assay and immunoblotting. The cell line continuously produces infectious HCV virions in culture. The virus particles produced from the culture had a buoyant density of 1.13 to 1.15 g/ml in sucrose and could infect primary human hepatocytes, peripheral blood mononuclear cells (PBMCs), and an established B-cell line (Raji cells) in vitro. The virus from SB cells belongs to genotype 2b. Single-stranded conformational polymorphism and sequence analysis of the viral RNA quasispecies indicated that the virus present in SB cells most likely originated from the patient's spleen and had an HCV RNA quasispecies pattern distinct from that in the serum. The virus production from the infected primary hepatocytes showed cyclic variations. In addition, we have succeeded in establishing several Epstein-Barr virus-immortalized B-cell lines from PBMCs of HCV-positive patients. Two of these cell lines are positive for HCV RNA as detected by reverse transcriptase PCR and for the nonstructural protein NS3 by immunofluorescence staining. These observations unequivocally establish that HCV infects B cells in vivo and in vitro. HCV-infected cell lines show significantly enhanced apoptosis. These B-cell lines provide a reproducible cell culture system for studying the complete replication cycle and biology of HCV infections.


Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 886-886 ◽  
Author(s):  
Lapo Alinari ◽  
Erin Hertlein ◽  
David M. Goldenberg ◽  
Rosa Lapalombella ◽  
Fengting Yan ◽  
...  

Abstract Mantle cell lymphoma (MCL) is an incurable B-cell malignancy and patients with this disease have limited therapeutic options. Despite the success of Rituximab in treatment of B-cell malignancies, its use as a single agent or in combination with chemotherapy in MCL has demonstrated modest activity; thus, novel strategies are needed. CD74 is an integral membrane protein expressed on malignant B cells and implicated in promoting survival and growth, making it an attractive therapeutic target. The humanized anti-CD74 monoclonal antibody (mAb), Milatuzumab, (Immunomedics) has shown promising preclinical activity against several human B-cell lymphoma cell lines, but has not been studied in MCL. Since Rituximab and Milatuzumab target distinct antigens lacking known association, we explored a combination strategy with these mAbs in MCL cell lines, patient samples, and in a preclinical model of MCL. Flow cytometric analysis shows that the MCL cell lines Mino and JeKo, and MCL patient tumor cells, express abundant surface CD74 compared to the CD74-negative cell line, Jurkat. Incubation of Mino and JeKo cells with immobilized (goat anti-human IgG) Milatuzumab (5 μg/ml) resulted in mitochondrial depolarization and significant induction of apoptosis determined by Annexin V/PI and flow cytometry (apoptosis at 8hr=38.3±0.85% and 25.4±2.6%; 24hr=73.6±3.47% and 36±3.57%; 48hr=84.9±3.91% and 50.4±4.17%, respectively, compared to Trastuzumab (control). Expression of surviving cells from anti-CD74-treated MCL cells consistently demonstrated marked induction of surface CD74 (MFI 762) compared to control (MFI 6.1). Incubation with immobilized Rituximab (10 μg/ml) resulted in 39.5±2.5% and 37.1±8.35% apoptotic events at 8hr, 58.8±3.14%, 41.2±8.27% at 24hr, and 40.1±1.3% and 45.6±3.25% at 48hr, respectively. Combination treatment of Mino and JeKo cells with Milatuzumab and Rituximab led to significant enhancement in cell death, with 77.6±3.95% and 79.6±2.62% apoptosis at 8hr in Jeko and Mino cells (P=0.0008 and P=0.00004 vs. Milatuzumab alone; P=0.00015 and P=0.001 vs. Rituximab alone); 90.4±3.53% and 76.6±4.3% at 24hr, respectively (P=0.0042 and P=0.0002 vs. Milatuzumab, P=0.0003 and P=0.0027 vs. Rituximab alone); 92.8±0.77% and 85.6±2.62% at 48hr, respectively (P= 0.026 and P=0.0002 vs. Milatuzumab alone, P=0.0000005 and P=0.00008 compared to Rituximab alone, respectively). To examine the in vivo activity of Rituximab and Milatuzumab, a preclinical model of human MCL using the SCID (cb17 scid/scid) mouse depleted of NK cells with TMβ1 mAb (anti-murine IL2Rb) was used. In this model, intravenous injection of 40×106 JeKo cells results in disseminated MCL 3–4 weeks after engraftment. The primary end-point was survival, defined as the time to develop cachexia/wasting syndrome or hind limb paralysis. Mice were treated starting at day 17 postengraftment with intraperitoneal Trastuzumab mAb control (300 μg qod), Milatuzumab (300 μg qod), Rituximab (300 μg qod), or a combination of Milatuzumab and Rituximab. The mean survival for the combination-treated group was 55 days (95%CI:41, upper limit not reached as study was terminated at day 70), compared to 33 days for Trastuzumab-treated mice (95% CI:31,34), 35.5 days for the Milatuzumab-treated mice (95% CI:33,37), and 45 days for the Rituximab-treated mice (95%CI:30,46). The combination treatment prolonged survival of this group compared to Trastuzumab control (P=0.001), Milatuzumab (P=0.0006) and Rituximab (P=0.098). No overt toxicity from Milatuzumab or the combination regimen was noted. A confirmatory study with a larger group of mice and detailed mechanistic studies are now underway. These preliminary results provide justification for further evaluation of Milatuzumab and Rituximab in combination in MCL.


Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3729-3729
Author(s):  
Heather Gilbert ◽  
John Cumming ◽  
Josef T. Prchal ◽  
Michelle Kinsey ◽  
Paul Shami

Abstract Abstract 3729 Poster Board III-665 Mantle cell lymphoma (MCL) is a well defined B-cell non-Hodgkin lymphoma characterized by a translocation that juxtaposes the BCL1 gene on chromosome 11q13, which encodes cyclin D1 (CD1), next to the immunoglobulin heavy chain gene promoter on chromosome 14. The resulting constitutive overexpression of CD1 leads to a deregulated cell cycle and activation of cell survival mechanisms. In addition, the gene which encodes GST-n, an enzyme that has been implicated in the development of cancer resistance to chemotherapy, is also located on chromosome 11q13 and is often coamplified along with the BCL1 gene in MCL (1). These two unique biological features of MCL - the overproduction of cyclin D1 and GST-n – may be involved in the carcinogenesis, tumor growth and poor response of this disease to treatment, and they offer potential mechanisms for targeted anti-cancer therapy. Nitric oxide (NO) is a biologic effector molecule that contributes to a host's immune defense against microbial and tumor cell growth. Indeed, NO is potently cytotoxic to tumor cells in vitro (2–4). However, NO is also a potent vasodilator and induces hypotension, making the in vivo administration of NO very difficult. To use NO in vivo requires agents that selectively deliver NO to the targeted malignant cells. A new compound has recently been developed that releases NO upon interaction with glutathione in a reaction catalyzed by GST-n. JS-K seeks to exploit known GST-n upregulation in malignant cells by generating NO directly in cancer cells, and it has been shown to decrease the growth and increase apoptosis in vitro in AML cell lines, AML cells freshly isolated from patients, multiple myeloma cell lines, hepatoma cells and prostate cancer cell lines (3, 5–7). JS-K also decreases tumor burden in NOD/SCID mice xenografted with AML and multiple myeloma cells (5, 7). Importantly, JS-K has been used in cytotoxic doses in the mouse model without significant hypotension. To evaluate whether JS-K treatment has anti-tumor activity in MCL, the human MCL cell lines Jeko1, Mino, Granta and Hb-12 were grown with media only, with JS-K at varying concentrations and with DMSO as an appropriate vehicle control. For detection of apoptotic cells, cell-surface staining was performed with FITC-labeled anti–Annexin V and PI. Cell growth was evaluated using the Promega MTS cytotoxicity assay. Results show that JS-K (at concentrations up to 10 μM) inhibits the growth of MCL lines compared to untreated controls, with an average IC50 of 1 μM. At 48 hours of incubation, all cell lines showed a significantly greater rate of apoptosis than untreated controls. A human MCL xenograft model was then created by subcutaneously injecting two NOD/SCID IL2Rnnull mice with luciferase-transfected Hb12 cells. Seven days post-injection, one of the mice was treated with JS-K at a dose of 4 μmol/kg (expected to give peak blood levels of around 17 mM in a 20 g mouse). Injections of JS-K were given intravenously through the lateral tail vein 3 times a week. The control mouse was injected with an equivalent volume of micellar formulation (vehicle) without active drug. The Xenogen bioluminescence imaging clearly showed a difference in tumor viability, with a significantly decreased signal in the JS-K treated mouse. Our studies demonstrate that JS-K markedly decreases cell proliferation and increases apoptosis in a concentration- and time-dependent manner in mantle cells in vitro. In a xenograft model of mantle cell lymphoma, treatment with JS-K results in decreased tumor viability. Proposed future research includes further defining the molecular basis of these treatment effects; using this therapy in combination with other cancer treatments both in vitro and in vivo; and studying JS-K treatment in MCL patients. Disclosures: Shami: JSK Therapeutics: Founder, Chief Medical Officer, Stockholder.


2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Mingkai Zhang ◽  
Yang Gao ◽  
Jialiang Wang ◽  
Zhanbo Liu ◽  
Zaishun Jin ◽  
...  

In order to determine a particular tumor cell via nanomaterials, we introduce the preparation of CD20 and CD5 coupled nanoprobes (denoted as CD20 and CD5 nanoprobes for convenience) and an application in identification of mantle cell lymphoma (MCL) from B-cell lymphoma. In this work, CD20 and CD5 nanoprobes were prepared by selectively oxidizing the carbon-carbon double bonds of oleate ligands on the surfaces of NaYF4:Yb3+,Tm3+ and NaYF4:Yb3+,Er3+ nanoparticles and, respectively, coupling carboxyl groups on the particles’ surfaces with CD20 and CD5 monoclonal antibodies through EDC/NHS crosslinking agents. After in situ hybridized Jeko-1 cells and Raji cells as a reference with CD20 and CD5 nanoprobes, in vitro double-color upconversion fluorescence imaging of Jeko-1 cells was demonstrated through visualization of blue and green fluorescence under a 980 nm laser excitation. Moreover, in vivo upconversion fluorescence imaging of the transplanted cancer model was also measured. These experimental results indicate that Jeko-1 cells have been specifically labeled by CD20 and CD5 nanoprobes. It is therefore concluded that CD20 and CD5 nanoprobes could be used to specially differentiate mantle cell lymphoma (MCL) from B-cell lymphoma.


Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3016-3016 ◽  
Author(s):  
Jack Wang ◽  
Victoria Zhang ◽  
Taylor Bell ◽  
Yang Liu ◽  
Hui Guo ◽  
...  

Abstract Background: Mantle cell lymphoma (MCL) is an incurable subtype of B-cell lymphoma. Ibrutinib, a first-in-class, once-daily, oral covalent inhibitor of Bruton's tyrosine kinase (BTK) was approved by the FDA for the treatment of MCL in patients previously treated. In our prior multicenter Phase 2 clinical trial, the overall response rate in relapsed/refractory MCL was 68%, with a median progression-free survival (PFS) of 13.9 months. However, the majority of MCL patients treated with ibrutinib relapsed; in these relapsed patients, the one-year survival rate was only 22%. Therefore, there exists an urgent need for additional novel targeted therapies to improve the mortality rate in these patients. In this study, we assessed the in vitro and in vivo effects of duvelisib, a PI3K-δ,-γ inhibitor, in MCL. Methods: The PI3K/AKT/mTOR and other cell survival signaling pathways were investigated by RNASeq and reverse phase protein array (RPPA) in ibrutinib-sensitive and -resistant MCL samples. The expression of PI3K isoforms, α, β, γ, and δ was tested in 11 MCL cell lines, patient and patient-derived xenograft (PDX) MCL cells by western blot analysis. We then investigated the growth inhibition and apoptosis of duvelisib (IPI-145, Infinity Pharmaceuticals, Inc.) in MCL cells by CellTiter-Glo® Luminescent Cell Viability Assay (Promega) and Annexin V-binding assay (BD Biosciences). We established a primary MCL-bearing PDX model and passaged the primary MCL tumor to next generations. Mice were administrated with 50 mg/kg duvelisib daily by oral gavage. Tumor burden and survival time were investigated in the MCL-PDX model. Results: We found that the PI3K/AKT/mTOR signaling pathway was activated in both primary and acquired ibrutinib-resistant MCL cell lines and PDX MCL cells. We immunoblotted PI3K isoforms, α, β, γ, and δ in 11 MCL cell lines and the result demonstrated that both ibrutinib-sensitive and ibrutinib-resistant MCL cells dominantly expressed PI3K-δ and -γ. Next, we tested the effects of duvelisib on these MCL cells. Duvelisib had effects on the growth inhibition and apoptosis in both ibrutinib-sensitive and ibrutinib-resistant MCL cells as good as the PI3K-δ inhibitor, idelalisib (Cal-101, GS-1101). The PI3K-δ isoform could play a very important role in PI3K-mediated signals in MCL. We then investigated the effects of duvelisib in vivo through our established MCL-bearing PDX mouse models. These models are created by inoculating the primary tumor cells from MCL patients into a human fetal bone chip implanted into NSG mice to provide a microenvironment that reconstitutes the human environment. MCL tumor mass was then passaged to next generations for therapeutic investigation of duvelisib. Mice were treated with 50 mg/kg duvelisib daily by oral gavage. Our data demonstrated that duvelisib significantly inhibited tumor growth and prolonged survival of MCL-PDX mice. Conclusion: Duvelisib, an oral dual inhibitor of PI3K-δ,-γ, inhibits MCL growth both in vitro and in PDX mice. These preclinical results suggests duvelisib may be effective in the treatment of patients with relapsed/refractory MCL. Disclosures No relevant conflicts of interest to declare.


Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4997-4997
Author(s):  
Andrea Rinaldi ◽  
Emilia Ceresa ◽  
Davide Rossi ◽  
Gianluca Gaidano ◽  
Shanta Bantia ◽  
...  

Abstract Mantle cell lymphoma (MCL) represents a subtype of B-cell lymphoma associated with a very unfavourable clinical outcome. Currently no therapy can be considered as standard, and new therapeutic approaches are needed. Forodesine is a potent inhibitor of purine nucleoside phosphorylase (PNP), whose major role is to catalyze the cleavage of inosine, deoxyinosine guanosine, and deoxyguanosine (dGuo) to their corresponding base and sugar 1-phosphate by phosphorolysis. In the presence of deoxycytidine kinase, PNP inhibition leads to an increase in the concentration of dGuo triphosphate (dGTP), followed by inhibition of DNA synthesis and cell death by apoptosis. When combined with dGuo, forodesine has been shown to have in vitro cytotoxic activity on T-cell (T-ALL, T-PLL) and on B-cell malignancies (CLL, B-ALL), and Phase I/II trials are on going in CLL and CTCL patients. Here, we report the first data on in vitro activity of forodesine in MCL. Primary MCL cells, derived from six patients, were exposed to forodesine (0, 2, 20 μM) in combination with dGuo (0, 10, 20 μM), for 48 hrs. Cells were cultured in X-VIVO 10 medium (Cambrex) with 10% FBS. Cell viability was assessed by flow cytometry with the Annexin V - propidium iodide assay. Four patient samples (67%) showed an increase in the number of Annexin V positive cells ranging from 1.9 to 5.3 times compared to untreated cells. The effect was larger for 20 μM forodesine compared with 2 μM. There was no effect of dGuo alone and only a minimal effect of increasing dGuo concentration from 10 μM to 20 μM. Cell lines did not appear to be ideal models to evaluate the efficacy of forodesine in vitro. Three established MCL cell lines (Granta-519, Rec, JeKo1) were treated with escalating doses of forodesine, but the results were not reproducible, while the same cells showed expected IC50 values between 25–30 μM when exposed to bendamustine for 72 hrs. In conclusion, the in vitro data reported here with 4/6 MCL patients primary samples sensitive to forodesine and the results from various groups on other T- and B-cell malignancies suggest that clinical trials of forodesine in MCL may be warranted.


Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3918-3918
Author(s):  
Arnau Montraveta ◽  
Mercè de Frías ◽  
Clara Campàs ◽  
Elias Campo ◽  
Gael Roue ◽  
...  

Abstract Abstract 3918 Mantle cell lymphoma (MCL) is a mature B-cell neoplasm characterized by the t(11;14)(q13:q32) that involves cyclin D1 overexpression and consequent cell cycle deregulation at the G1 phase. This entity is generally characterized by an aggressive course and a bad prognosis. Recently, a specific subtype of MCL has been described, showing best outcomes and that might be managed more conservatively than conventional MCL. These cases are characterized by non-nodal presentation, predominantly hypermutated IgVH, lack of genomic complexity, and absence of SOX11 expression. Acadesine is a nucleoside analogue initially developed as a cardioprotective agent, and which has shown a wide range of metabolic effects, including the activation of AMP-activated protein kinase (AMPK). Acadesine was shown to induce apoptosis in primary cells from several B lymphoid neoplasms and has been entered in a phase I/II clinical trial with relapsed/refractory chronic lymphocytic leukemia (CLL) patients. This clinical study has shown that acadesine plasmatic levels in the micro molar range are achievable and safe when CLL patients are treated with the drug. To evaluate the antitumoral properties of acadesine in MCL, we exposed a set of 11 MCL primary cultures and 9 MCL cell lines for up to 48h with increasing doses of the drug. Cytotoxicity and cytostatic effects were then assessed by flow cytometry detection of annexinV/propidium iodide labeling and MTT proliferation assay, respectively. In both MCL cell lines and MCL primary cultures, we observed a heterogeneous response to the drug, with no correlation to common genetic alterations such as deletion/mutation of P53, ATM or P16 genes. JVM2, Jeko-1, Rec-1 and UPN-1 were the more sensitive cell lines, with a mean lethal dose 50 (LD50) of 1.57 mM at 24 h and 0.95 mM at 48h, while 2 cell lines (HBL-2 and Granta-519) showed a primary resistance to the compound (LD50 > 50 mM). Among MCL primary cultures, acadesine showed selective cytotoxic activity against malignant B cells while sparing accompanying T cells. Of note, those cases corresponding to the indolent MCL group showed increased sensitivity to the drug at 24h of treatment, when compared to conventional MCL cases (p=0.03). We observed that acadesine efficiently activates the intrinsic apoptotic pathway in MCL cells by modulating Bcl-2 family protein levels, leading to conformational activation of Bax and Bak, mitochondrial depolarization, generation of reactive oxygen species and caspases processing. In drug combination assays, acadesine showed a synergistic effect when combined with Rituximab, being the Rituximab-acadesine combination more potent than other Rituximab-based polychemotherapies such as R-bendamustine and R-CHOP. Finally, a daily administration of 400mg/kg acadesine in mice previously inoculated with a MCL xenotransplant significantly reduced tumor burden when compared to control animals, as soon as 7 days of treatment. In summary, these results suggest that acadesine exerts significant antitumoral activity in both in vitro and in vivo model of MCL, and may represent an attractive model for the design of a new therapeutic approach for this entity, especially in patients presenting with the indolent form. Disclosures: de Frías: Advancell therapeutics: Employment. Campàs:Advancell therapeutics: Employment.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2734-2734
Author(s):  
Kejie Zhang ◽  
Lan V Pham ◽  
Liang Zhang ◽  
Archito T. Tamayo ◽  
Zhishuo Ou ◽  
...  

Abstract Abstract 2734 Chromosomal Region Maintenance 1 (CRM1) overexpression has been associated with cancer progression and mortality in several human cancers, suggesting that activation of nuclear export may play a role in human neoplasia and may serve as a novel target for the treatment of cancers. This overexpression of CRM1 may be related to the export of most tumor suppressor and growth regulatory proteins out of the nucleus, thereby functionally inactivating them. Mantle cell lymphoma (MCL) is an aggressive histotype of B-cell non-Hodgkin lymphoma that is not yet curable. The objective of our study was to investigate the status of CRM1 in MCL, both in MCL cell lines and primary MCL cells, in comparison to normal B cells, and to evaluate the therapeutic efficiency of CRM1 inhibition in MCL in vitro and in vivo, and to elucidate the mechanism of CRM1 inhibitor-mediated MCL cell apoptosis. We used 8 established MCL cell lines and primary cells from 4 patients with relapsed/refractory MCL. KPT185 and KPT276 are novel, highly selective, drug-like small molecular CRM1 inhibitors. Western Blot analysis showed that CRM1 was expressed in both the cytoplasm and nuclei of 8 MCL cell lines. CRM1 was mainly detected in nuclei of normal resting B cells; In contrast, CRM1 was primarily detected in the cytoplasm of freshly isolated primary MCL cells from patients with relapsed/refractory MCL. In 3H-thymidine incorporation assays, inhibition of CRM1 by KPT185 resulted in a significant dose-dependent growth inhibition of 8 MCL cells, with IC50 values range between 10 nM to 120 nM. The blastoid-variant MCL cell lines (Z-138 and Rec-1) were significantly more sensitive to KPT185 than the non-blastoid variant MCL cell lines. Flow cytometry analysis with fluorescence-labeled Annexin V and propidium iodide showed that KPT185 induced MCL cells apoptosis in both time- and dose-dependent manners, but had no effect on cell cycle arrest. MCL cells treated with KPT185 for 12 hours showed caspase 3 activation and PARP cleavage. As shown in Western blot and confocal microscopy, blocking CRM1 activity by KPT185 in MCL cells up-regulated the protein expression of p53, a known CRM1-mediated export protein, and also induced CRM1 translocation to the nucleus and decreased CRM1 expression. In severe combined immunodeficient (SCID) mice bearing palpable Z-138 tumors, treatment with KPT-276 (similar structure to KPT-185 but improved animal pharmacokinetics), 50mg/kg or 150 mg/kg PO QDx5 each week, or cyclophosphamide 100 mg/kg on days 1–3, was initiated. Tumor growth was significantly inhibited (>75%) in all of treatment groups compared with vehicle control. Neutropenia and other cytotoxic-agent specific effects have not been observed in treated animals. In conclusion, CRM1 inhibitors inhibited growth of MCL cells in vitro and in vivo, and induced apoptosis of MCL cells via inhibition of CRM1 expression and blockage of its translocation with functional nuclear proteins. Our data suggest that novel CRM1 inhibitors provide a potential therapy for patients with relapsed/refractory MCL. Disclosures: No relevant conflicts of interest to declare.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2276-2276
Author(s):  
Andrea Aroldi ◽  
Mario Mauri ◽  
Matteo Parma ◽  
Elisabetta Terruzzi ◽  
Marilena Fedele ◽  
...  

Abstract Introduction Mantle-cell lymphoma (MCL) is a B-cell non-Hodgkin Lymphoma (NHL) characterized by heterogenous behavior, ranging from indolent phenotype to highly aggressive and drug resistant one with dismal prognosis. Drug resistance may be generated by Tumor Microenvironment (TME), owing that Tumor-Associated Macrophages (TAM) are pathologically functional in providing survival signals to MCL cells (Pham, Front Oncol. 2018). Recently, "Don't Eat Me" signal (DEMs) blockade with anti-CD47 monoclonal Antibody (moAb) showed promising activity in pretreated NHL, through increase of phagocytosis by TAM (Advani, NEJM. 2019). CD24 was also demonstrated to be involved in DEMs and, in a preclinical model of solid cancer, blocking the CD24/Siglec-10 interaction provided an improvement of M2-like TAM-mediated phagocytosis in vitro and an increase of survival in vivo (Barkal, Nature. 2019). CD24 can be expressed in some phases of B-cell differentiation and MCL derives from a B-cell precursor with upregulated CD24. To date, there are no functional studies showing an improvement of phagocytosis through CD24/Siglec-10 pathway inhibition in hematologic malignancies and MCL. Here, we present our in vitro results of CD24/Siglec-10 DEMs blockade in MCL subset. Methods A panel of MCL cell lines (Jeko-1, Granta-519, Mino) has been analyzed for CD24 surface expression by flow cytometry (FC) (clone SN3). Consequently, we performed co-culture experiments with MCL cell lines and macrophages from healthy donors. Briefly, Peripheral Blood Mononucleated Cells (PBMC) were collected from healthy volunteers through density gradient centrifugation technique. CD14+ monocytes were isolated through CD14 Microbeads isolation kit and cultured in plates with 50 ng/ml human GM-CSF for 7-9 days. In order to create M2-like Siglec-10+ TAM, 50 ng/ml human IL-10 and 50 ng/ml human TGF-β 1 were added on days 3-4 of differentiation until use on days 7-9. Siglec-10 expression on TAM was checked by FC (clone 5G6). M2-like macrophages were then collected and co-cultured with CFSE-labelled MCL target cells for 1-2 hours in a serum-free medium. Anti-CD24 moAb (clone SN3) or the appropriate IgG 1 isotype control were added at a concentration of 10 μg/ml. Phagocytosis was then stopped on ice and CD11b-PE staining (anti-CD11b moAb, clone REA713) was performed to identify human macrophages by FC. Phagocytosis was measured as the number of CD11b+/CFSE+ macrophages, quantified as a percentage of the total CD11b+ macrophages. Each phagocytosis reaction was performed in technical triplicate and phagocytosis was normalized to the highest technical replicate per donor in order to consider raw phagocytic level among donor-derived macrophages. Results MCL cell lines express surface CD24 by FC, with higher levels in Mino cell line (Figure 1A). Differentiated M2-like macrophages showed an upregulation of Siglec-10 expression after immunosuppressive stimuli, which is fundamental owing that Siglec-10 is the ligand of CD24 (Figure 1B). As pertains to the phagocytic assay, we documented an improvement of phagocytosis when M2-like macrophages and MCL cell lines were co-cultured together with anti-CD24 moAb (Figure 2 and Figure 3A). Furthermore, it is worth mentioning that phagocytosis seemed to be much higher in MCL cell lines with higher surface levels of CD24 (e.g., Mino), presenting increased number of CD11b+/CFSE+ M2-like TAM by FC (Figure 3B). Conclusions MCL was found to be sensitive to CD24/Siglec-10 DEMs blockade when co-cultured with M2-like macrophages in vitro. We can argue that most of the observed increase of phagocytosis after the addition of anti-CD24 moAb may be secondary to loss of CD24 signalling rather than Fc-mediated opsonization, as already documented in previous analysis about solid cancer (Barkal, Nature. 2019). We can therefore hypothesize that the blockade of this DEMs pathway can improve phagocytosis in a non-opsonization manner in NHL as well. Furthermore, CD24 surface density seemed to be positively correlated to the intensity of phagocytic activity, suggesting that MCL subtypes expressing higher CD24 levels are much more dependent on this DEMs pathway than others with low CD24 density. Overall, CD24 turned out to be a potential immunotherapeutic target in MCL, aiming at improving innate immune system through DEMs blockade. In vivo studies are needed to confirm the activity we documented in vitro in this NHL subset. Figure 1 Figure 1. Disclosures Gambacorti-Passerini: Bristol-Myers Squibb: Consultancy; Pfizer: Honoraria, Research Funding.


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