Delivery strategies of RNA therapeutics for ex vivo and in vivo B-cell malignancies

Abstract We conducted a clinical trial to assess adoptive transfer of T cells genetically modified to express an anti-CD19 chimeric Ag receptor (CAR). Our clinical protocol consisted of chemotherapy followed by an infusion of anti–CD19-CAR–transduced T cells and a course of IL-2. Six of the 8 patients treated on our protocol obtained remissions of their advanced, progressive B-cell malignancies. Four of the 8 patients treated on the protocol had long-term depletion of normal polyclonal CD19+ B-lineage cells. Cells containing the anti-CD19 CAR gene were detected in the blood of all patients. Four of the 8 treated patients had prominent elevations in serum levels of the inflammatory cytokines IFNγ and TNF. The severity of acute toxicities experienced by the patients correlated with serum IFNγ and TNF levels. The infused anti–CD19-CAR–transduced T cells were a possible source of these inflammatory cytokines because we demonstrated peripheral blood T cells that produced TNF and IFNγ ex vivo in a CD19-specific manner after anti–CD19-CAR–transduced T-cell infusions. Anti–CD19-CAR–transduced T cells have great promise to improve the treatment of B-cell malignancies because of a potent ability to eradicate CD19+ cells in vivo; however, reversible cytokine-associated toxicities occurred after CAR–transduced T-cell infusions. This trial was registered with ClinicalTrials.gov as NCT00924326.

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IMMU-29. B-CELL-BASED VACCINE PRODUCES GLIOBLASTOMA-REACTIVE ANTIBODIES THAT CONTRIBUTE TO TUMOR CLEARANCE

Neuro-Oncology ◽

10.1093/neuonc/noab196.388 ◽

2021 ◽

Vol 23 (Supplement_6) ◽

pp. vi98-vi98

Author(s):

Brandyn Castro ◽

Mark Dapash ◽

David Hou ◽

Aida Rashidi ◽

Deepak Kanojia ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Humoral Immunity ◽

Ex Vivo ◽

Murine Models ◽

Effector Functions ◽

Tumor Bearing ◽

Tumor Clearance ◽

Cellular And Humoral Immunity

Abstract Glioblastomas (GBM) are characterized by a strong immunosuppressive environment, contributing to their poor prognosis and limited therapeutic response to immunotherapies. B-cells represent a unique opportunity to promote immunotherapy due to their potential to kill tumors by both cellular and humoral immunity. To generate our B-cell-based vaccine (BVax) platform, we activated 41BBL+ B cells from tumor bearing mice or GBM patient blood with BAFF, CD40, and IFNg. We have previously demonstrated that BVax potentiates radiation therapy, temozolomide and checkpoint blockade in murine models of GBM via enhancement of CD8+ T-cell based immunity. The aim of this current study is to evaluate the humoral effector functions of BVax. We examined the antibody (Ab) repertoire in vivo from serum of tumor-bearing B-cell knockout mice treated with BVax or by ex vivo stimulation of patient-derived BVax. Upon systemic administration, BVax infiltrates the tumor where it differentiates into plasmablasts. Murine BVax- and BNaive-derived serum immunoglobulin generated in vivo showed that the majority of murine BVax-derived Ab were IgG isotype, while BNaive mainly produced IgM isotype. Transfer of IgG from BVax treated mice directly into tumors of recipient animals significantly prolonged their survival, demonstrating anti-tumor cytotoxicity directly through humoral immunity. Patient-derived BVax activated ex vivo showed a plasmablast phenotype and the Ab repertoire supports the previous findings seen in our murine model. Our work suggests BVax-derived IgGs role in antibody-dependent cellular cytotoxicity and improved survival in murine models. This function, in addition to its role in cellular immunity against GBM, renders BVax a potentially effective alternative immunotherapeutic option for GBM patients.

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Chimeric CLL-1 Antibody Fusion Proteins Containing Granulocyte-Macrophage Colony-Stimulating Factor or Interleukin-2 With Specificity for B-Cell Malignancies Exhibit Enhanced Effector Functions While Retaining Tumor Targeting Properties

Blood ◽

10.1182/blood.v89.12.4437 ◽

1997 ◽

Vol 89 (12) ◽

pp. 4437-4447 ◽

Cited By ~ 35

Author(s):

Jason L. Hornick ◽

Leslie A. Khawli ◽

Peisheng Hu ◽

Maureen Lynch ◽

Peter M. Anderson ◽

...

Keyword(s):

B Cell ◽

Fusion Proteins ◽

Tumor Targeting ◽

B Cell Malignancies ◽

Gm Csf ◽

Macrophage Colony Stimulating Factor ◽

Macrophage Colony ◽

Stimulating Factor

Abstract Although monoclonal antibody (MoAb) therapy of the human malignant lymphomas has shown success in clinical trials, its full potential for the treatment of hematologic malignancies has yet to be realized. To expand the clinical potential of a promising human-mouse chimeric antihuman B-cell MoAb (chCLL-1) constructed using the variable domains cloned from the murine Lym-2 (muLym-2) hybridoma, fusion proteins containing granulocyte-macrophage colony-stimulating factor (GM-CSF) (chCLL-1/GM–CSF) or interleukin (IL)-2 (chCLL-1/IL–2) were generated and evaluated for in vitro cytotoxicity and in vivo tumor targeting. The glutamine synthetase gene amplification system was employed for high level expression of the recombinant fusion proteins. Antigenic specificity was confirmed by a competition radioimmunoassay against ARH-77 human myeloma cells. The activity of chCLL-1/GM–CSF was established by a colony formation assay, and the bioactivity of chCLL-1/IL–2 was confirmed by supporting the growth of an IL-2–dependent T-cell line. Antibody-dependent cellular cytotoxicity against ARH-77 target cells demonstrated that both fusion proteins mediate enhanced tumor cell lysis by human mononuclear cells. Finally, biodistribution and imaging studies in nude mice bearing ARH-77 xenografts indicated that the fusion proteins specifically target the tumors. These in vitro and in vivo data suggest that chCLL-1/GM–CSF and chCLL-1/IL–2 have potential as immunotherapeutic reagents for the treatment of B-cell malignancies.

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A Non-Internalizing Anti-CD40 Antibody, CHIR-12.12, Blocks CD40L-Induced Cytokine Production and Mediates Greater ADCC Than Rituximab in Primary CLL Cells.

Blood ◽

10.1182/blood.v106.11.2964.2964 ◽

2005 ◽

Vol 106 (11) ◽

pp. 2964-2964

Author(s):

Xia Tong ◽

Sharon Lea Aukerman ◽

Karen Lin ◽

Natasha Aziz ◽

Cheryl Goldbeck ◽

...

Keyword(s):

Cell Surface ◽

B Cell ◽

Cytokine Production ◽

Ex Vivo ◽

Lymphocytic Leukemia ◽

Target Cells ◽

Adcc Activity ◽

Effector Cells ◽

Cells Cultured

Abstract CD40 is expressed on chronic lymphocytic leukemia (CLL) cells, and CD40 activation leads to signaling critical for cell survival and proliferation. We have previously described a novel, fully human IgG1 anti-CD40 antagonistic monoclonal antibody, CHIR-12.12, generated in XenoMouse® mice (Abgenix, Inc.), and have demonstrated that it inhibits normal human B cell proliferation and survival and mediates potent antibody-dependent cellular cytotoxicity (ADCC) against primary CLL and non-Hodgkin’s lymphoma cells. In this study, we examined the ability of CHIR-12.12 to modulate cytokine production by primary CLL cells and compared the ADCC activity of CHIR-12.12 with rituximab against primary CLL cells. Primary CLL cells stimulated with CD40L produced a variety of cytokines, including IL-10, TNF-α , IL-8, GM-CSF, IL-6, MCP-1, and MIP-1β. Addition of CHIR-12.12 to primary CLL cells inhibited CD40L-mediated production of these cytokines. Cytokine production by primary CLL cells cultured with CHIR-12.12 alone in the absence of CD40L did not exceed levels produced by CLL cells cultured in medium. These data suggest that CHIR-12.12 is a potent antagonist for CD40L-mediated cytokine production by primary CLL cells and shows no agonistic activity by itself. We next compared the relative ADCC activity of CHIR-12.12 and rituximab against ex vivo primary CLL cells from 8 patients. CHIR-12.12 exhibited greater ADCC than rituximab against CLL cells from all patients. The average percent of maximum lysis by CHIR-12.12 and rituximab were 49 ± 16% and 31 ± 14%, respectively. CHIR-12.12 was greater than 10-fold more potent than rituximab, as measured by ED50 values (14.1 pM versus 155.5 pM, respectively). Quantitative CD20 and CD40 density on CLL cells and the degree of antibody internalization were investigated as potential reasons for the difference in ADCC activity. The greater ADCC potency and efficacy of CHIR-12.12 was not dependent on a higher density of cell surface CD40 molecules, as there were 1.3 to 14-fold higher numbers of CD20 than CD40 molecules on the cell surface. Antibody internalization studies using primary CLL cells conducted by flow cytometry and confocal microscopy show that upon binding to CD40 at 37°C, CHIR-12.12 remains uniformly distributed on the cell surface, even after 3 hours. In contrast, after binding at 37°C, rituximab is redistributed into caps and internalized. These data suggest that the potent ADCC activity of CHIR-12.12 may be partly related to its ability to remain on the surface of target cells uniformly, allowing optimal interaction with effector cells. Taken together, these results suggest that CHIR-12.12 may be effective at mediating potent ADCC against CLL cells in vivo. CHIR-12.12 is currently in Phase I trials for B-cell malignancies.

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Screening Thousands of Drugs in Leukemia Patient Samples to Identify Novel Uses for Approved Drugs.

Blood ◽

10.1182/blood.v114.22.4414.4414 ◽

2009 ◽

Vol 114 (22) ◽

pp. 4414-4414

Author(s):

Teresa A Bennett ◽

Sandra Sapia ◽

Daniel Primo ◽

Lilia Suarez ◽

Santiago Lago ◽

...

Keyword(s):

B Cell ◽

Research Funding ◽

Ex Vivo ◽

Lymphocytic Leukemia ◽

Cytotoxic Drugs ◽

Intravenous Bolus ◽

Malignant Cells ◽

B Cell Malignancies ◽

Technology Platform ◽

Approved Drugs

Abstract Abstract 4414 Introduction Discovery of novel non cytotoxic drugs for cancer focuses on targets selectively expressed in malignant cells, only testing at the end if they are toxic to patients. We have developed a novel approach to discover these drugs starting at the end; we screen 2.000 approved drugs with proven safety, directly on freshly extracted (ex vivo) blood samples of patients with Chronic Lymphocytic Leukemia (CLL). These screens are enabled by a novel technology platform based on automated flow cytometry we call ExviTech for ex vivo technology. Patients and Methods All screening studies were performed directly on either peripheral blood or bone marrow samples from 44 patients diagnosed with various subtypes of B-cell malignancies, after informed consent. Patient samples were diluted and plated with each of the 2.000 drugs individually, retaining the erythrocyte population and serum proteins to enable clinically relevant concentrations. The experimental assay was setup the same or a day after sample extraction. Each sample was diluted to achieve a leukemic cell concentration of approximately 3,000 cells/μl; then 45μl of the suspension is added to each well of 96-well plates that contain the pharmacological agents (final concentration of 30μM). The compound plates were then sequentially incubated for 24 hours at 37°C with 5% CO2 for screening (sterile conditions). After incubation, the erythrocytes were lysed and the leucocytes incubated with Annexin V-FITC, anti-CD45-APC and anti-CD19-PE added to each well. The plates were then transferred to an automated flow cytometry system where the contents of each well were aspirated and analyzed by a CyAn flow cytometer. Candidates from the primary screens were validated in additional samples with dose-responses, combinations with approved drugs, multiple incubation times, etc… Results Analyzing primary screens from 24 CLL patients, three related compounds (Vivia007, Vivia008 and Vivia009) were found to consistently induce apoptosis of nearly all leukemic B-cells from most of the patient samples diagnosed with B-cell chronic lymphocytic leukemia at levels equal to or greater than known CLL active cytotoxic agents. Notably, these candidates are equally effective against samples of p53 mutated patients. These 3 drugs are pharmacologically me-too drugs sharing the same target and mechanism of action, and are non cytotoxic drugs with a known and good safety profile, administered to millions of patients over many years. Validation experiments were done on 20 additional CLL patients and Vivia009 emerged as the most effective agent with an average EC50 of 18.2μM. The mechanism of action is different than the known mechanism of Vivia009 and its class members for their approved indications. Consistent with this observation, only 3 of 15 members of the same pharmacological drug class were efficacious against CLL malignant cells. All 3 Vivia′s candidates were equally efficacious against other B-Cell Malignancies such as B-ALL (pediatric and adult), and Multiple Myeloma. These drugs are not effective in their current oral formulation and require a novel intravenous formulation. Interestingly, kinetics of induction of apoptosis were faster for Vivia009 than for fludarabine, cyclophosphamide and mitoxantrone. Vivia009 requires only 1 hour of incubation with fresh cells to induce maximal apoptosis. This timeline is less than the 3 hours in which Vivia009 was found present at high concentrations in bone marrow of rats using a single intravenous bolus. Thus, Vivia009 seems to fulfill the pharmacokinetic criteria to eliminate all leukemic cells with a single intravenous bolus, which would be a major advantage over current treatments (5-days fludarabine or 3 days FCR). Animal models are ongoing to confirm the non cytotoxic nature of the candidates in the novel IV formulation and the fewer days needed to reach remission, both compared with fludarabine monotherapy. Conclusions In summary, our results demonstrate the potential of the ExviTech technology platform as a successful model for the systematic search of new uses for already existing approved drugs directly on patient samples of hematological malignancies. A new drug candidate with excellent safety profile has been identified with similar efficacy ex vivo as the best approved cytotoxic drugs, which is a non-cytotoxic drug with fast kinetics that might enable significantly safer and shorter treatments. Disclosures: Bennett: Vivia Biotech: Employment. Sapia:Vivia Biotech SL: Employment. Primo:Vivia Biotech SL: Employment. Suarez:Vivia Biotech SL: Employment. Lago:Vivia Biotech SL: Employment. Matoses:Vivia Biotech: Employment. Espinosa:Vivia Biotech: Ana Espinosa, Employment. Tudela:Vivia Biotech SL: Employment. Arroyo:Vivia Biotech SL: Employment. Jackson:Vivia Biotech SL: Employment. Okun:Vivia Biotech SL: Research Funding. Lopez:Vivia Biotech SL: Employment. Gornemann:Vivia Biotech SL: Employment. Diez:Vivia Biotech SL: Employment. González:Vivia Biotech SL: Consultancy. Dominguez-Gil:Vivia Biotech SL: Consultancy. Troconiz:Vivia Biotech SL: Consultancy. Rodriguez de Fonseca:Vivia Biotech SL: Consultancy. Saunders:Vivia Biotech: Consultancy. Montejo:Vivia Biotech SL: Consultancy. Caveda:Vivia Biotech SL: Employment. Orfao:Vivia Biotech SL: Research Funding. Ballesteros:Vivia Biotech SL: Equity Ownership.

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TRU-016, An Anti-CD37 SMIP™ Biologic, In Combination with Other Therapeutic Drugs In Models of Non-Hodgkin's Lymphoma

Blood ◽

10.1182/blood.v116.21.3931.3931 ◽

2010 ◽

Vol 116 (21) ◽

pp. 3931-3931 ◽

Cited By ~ 4

Author(s):

Paul A. Algate ◽

Jennifer Wiens ◽

Christy Nilsson ◽

Mien Sho ◽

Debra T. Chao ◽

...

Keyword(s):

Tumor Growth ◽

Follicular Lymphoma ◽

B Cell ◽

Cell Lymphoma ◽

Combination Index ◽

Growth Delay ◽

Tumor Growth Delay ◽

B Cell Malignancies

Abstract Abstract 3931 Background: CD37 is a 50–55 kDa heavily glycosylated member of the tetraspanin superfamily of molecules. This cell surface protein is expressed on normal and transformed B-cells, and has been implicated in diverse processes including cellular activation and proliferation, cell motility, and cell-cell adhesion. TRU-016 is a novel humanized anti-CD37 SMIP™ protein. Pre-clinical studies have demonstrated that anti-CD37 SMIP™ protein mediates caspase-independent direct killing of normal and malignant B-cells, a mechanism of action that appears to be different than CD20 therapies. In addition, TRU-016 results in indirect killing through NK cell mediated SMIP-protein directed cellular cytotoxicity (SDCC). The therapeutic potential of TRU-016 against several subsets of B-cell malignancies is currently being investigated in the clinic. Methods: The ability of TRU-016 to interact and increase cell killing with established therapeutics rituximab (anti-CD20 antibody), bendamustine (bi-functional alkylating agent/nucleoside analog), LY294002 (PI3K inhibitor) and temsirolimus (mTOR inhibitor) was investigated in vitro using the Rec-1 (mantle cell lymphoma) and SU-DHL-6 (diffuse large B cell lymphoma) cell lines. Individual drugs were tested in combination with TRU-016 as well as in a multiple drug cocktail. Combination index analyses were performed for drug combinations over the 20–90% effect levels. To determine whether in vitro synergy could be recapitulated in vivo, DoHH-2 (follicular lymphoma) xenografts were treated with TRU-016, bendamustine, and the combination of TRU-016 and bendamustine with or without rituximab. Furthermore, the effect of the dosing schedule with the combination of TRU-016 and rituximab was explored by comparing the treatment over a short time period to an extended (maintenance) dosing regimen. CD37 expression on the tumor xenografts was evaluated post different treatment by immunohistochemistry. Results: Combination index analyses determined that the killing effects of TRU-016 was synergistic with rituximab, bendamustine and temsirolimus in NHL models. Furthermore, TRU-016 provided additional efficacy when added to the combination of rituximab and bendamustine. In vivo results demonstrated that the in vitro synergy results were applicable to a more complex in vivo disease model. The combination of TRU-016 with bendamustine or rituximab resulted in increased tumor growth delay compared to that attained with the individual drugs. The addition of TRU-016 to the combination of bendamustine and rituximab resulted in increased tumor growth delay compared to the two drugs alone. The observed efficacy of the combination of TRU-016 and rituximab could be extended with repeated (maintenance) dosing with tumor free survival being observed beyond the 35 days of dosing. The combination of TRU-016 with temsirolimus also resulted in a reduction of tumor growth compared to either molecule alone. CD37 target expression was detected in the xenograft tumors post-treatment with all drugs tested. Conclusions: TRU-016 in combination with rituximab, bendamustine or temsirolimus increased cell killing of NHL cells in vitro over that observed for each agent alone. Furthermore, the triple combination of TRU-016 with rituximab, bendamustine or temsirolimus displayed greater anti-tumor activity in vivo than each of the agents alone against a follicular lymphoma tumor model. The addition of TRU-016 to a combination of rituximab and bendamustine resulted in increased killing in vitro and in vivo. The combinatorial activity of TRU-016 and rituximab in vivo was increased when the drugs were administered over a longer period. These results provide preclinical rationale for the potential different combinations of TRU-016 with several established therapeutics for the treatment of NHL and related B-cell malignancies. Disclosures: Algate: Trubion Pharmaceuticals: Employment. Wiens:Trubion Pharmaceuticals: Employment. Nilsson:Trubion Pharmaceuticals: Employment. Sho:Facet/Abbott: Employment. Chao:Facet/Abbott: Employment. Starling:Facet/Abbott: Employment. Gordon:Trubion Pharmaceuticals: Employment.

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Targeting Mir-548m-HDAC6 Axis Circumvents Stroma- Mediated Drug Resistance (CAM-DR) and Clonogenicity in Non-Hodgkin B-Cell Lymphomas

Blood ◽

10.1182/blood.v120.21.5094.5094 ◽

2012 ◽

Vol 120 (21) ◽

pp. 5094-5094

Author(s):

Tint Lwin ◽

Xiaohong Zhao ◽

Fengdong Cheng ◽

Xinwei Zhang ◽

Yizhuo Zhang ◽

...

Keyword(s):

Drug Resistance ◽

Lymph Node ◽

B Cell ◽

Conflicts Of Interest ◽

Ex Vivo ◽

Lymphoma Cell ◽

Histone Deacetylase 6 ◽

B Cell Lymphomas ◽

Non Hodgkin Lymphoma

Abstract Abstract 5094 A dynamic interaction occurs between the lymphoma cell and its microenvironment, with each profoundly influencing the behavior of the other. Here, we demonstrate that adhesion of mantle cell lymphoma (MCL) and other non-Hodgkin lymphoma cells to lymph node stromal cells, follicular dendritic cells (FDCs), confers drug resistance, enhances lymphoma cell clonogenicity, and is associated with induction of histone deacetylase 6 (HDAC6). Furthermore, stroma down-regulated miR-548m contributes to HDAC6 up-regulation, and HDAC6 is a key determinant for FDC-mediated lymphoma cell survival and colony formation. We further showed that stroma-mediated drug resistance and clonogenic growth are reversed by enforced expression of miR-548m and inhibition of HDAC6. The HDAC6-selective inhibitor tubastatin significantly enhances cell death, abolishes cell adhesion-mediated drug resistance, and suppresses clonogenicity and lymphoma growth suppression ex vivo and in vivo. Together, these data suggest that the lymphoma–stroma interaction in lymph node microenvironment directly impacts the biology of lymphoma through epigenetic regulation of miRNA and HDAC, with HDAC6 as a potential therapeutic target to overcome drug resistance in MCL and other B-cell lymphomas. Disclosures: No relevant conflicts of interest to declare.

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Overexpression of BCL9, a Wnt/β-Catenin Transcriptional Co-Activator, in Transgenic Mice Promotes Spontaneous Development of B-Cell Malignancies

Blood ◽

10.1182/blood.v128.22.441.441 ◽

2016 ◽

Vol 128 (22) ◽

pp. 441-441

Author(s):

Tomasz Sewastianik ◽

Jianjun Zhao ◽

Meng Jiang ◽

Peter S. Dennis ◽

Myles Brown ◽

...

Keyword(s):

B Cells ◽

Transgenic Mice ◽

B Cell ◽

Signaling Pathway ◽

Transcriptional Activity ◽

Hematological Malignancies ◽

B Cell Malignancies ◽

Human Cancers ◽

Stop Cassette

Abstract Dysregulation of the Wnt signaling pathway underlies the pathogenesis of a wide range of human cancers, including hematological malignancies such as multiple myeloma (MM). The terminal effector of this signaling pathway is a transcriptional complex formed by β-catenin and BCL9. This complex is of particular interest because the BCL9 locus resides on the frequently recurring 1q21 chromosomal amplification in MM, which has been linked to poor clinical prognosis and outcome. Our previous studies indicate that BCL9-mediated enhancement of β-catenin activity increases cells proliferation, migration, invasion, and the metastatic potential of MM cells. Therefore, in order to: (I) unequivocally determine the oncogenic role of BCL9, (II) better understand its mechanism of action, and (III) develop mouse preclinical model of cancer with dysregulated Wnt/β-catenin/BCL9 activity, we generated transgenic mouse models. To overcome problems inherently related to embryonic lethality, we generated BCL9fl/- conditional transgenic mice using site-specific transgene integration into the mouse ColA1 gene in embryonic stem cells. To remove the stop cassette and activate BCL9 expression in vivo, we generated AID-Cre+/-; BCL9fl/- and ERT2-Cre+/-; BCL9fl/- compound mice. Recombinase activity driven by AID (activation-induced cytidine deaminase) gene promoter or ER receptor after tamoxifen administration, caused removal of the stop cassette and expression of BCL9 in germinal center (GC) B cells or several tissues, respectively, as confirmed by immunoblot, immunohistochemical (IHC) and PCR analysis. Since BCL9 is a β-catenin co-activator, next we generated cohorts of AID-Cre+/-; BCL9fl/-; TCF/Lef1-lacZ+/- and ERT2-Cre+/-; BCL9fl/-; TCF/Lef1-lacZ+/- triple compound transgenic mice carrying the Wnt reporter system that expresses β-galactosidase (β-gal), to determine whether Wnt/β-catenin transcriptional activity is increased as a consequence of BCL9 overexpression in vivo. β-gal stain was increased in frequency and intensity in cells within GCs but not outside them in AID-Cre+/-; BCL9fl/-; TCF/Lef1-lacZ+/- compared to control mice. In ERT2-Cre+/-; BCL9fl/-; TCF/Lef1-lacZ+/- mice β-gal staining was primarily detected in cells outside the GCs, not within them. Overall, these results indicate that Wnt transcriptional activity is increased in B-cells as a consequence of Cre-induced expression of BCL9 and that AID-Cre+/- and ERT2-Cre+/- target expression of BCL9 to GC and non-GC B cells, respectively. Because BCL9 is involved in the pathogenesis of human cancers, we evaluated whether our transgenic mice develop hematological malignancies. Except for mild splenic enlargement, BCL9-transgenic mice were indistinguishable from control mice between 8 and 30 weeks of age as assessed by weight and posture. However, after 40 weeks of age and at variable times thereafter, 80% (32/40) of AID-Cre+/-; BCL9fl/- and 70% (28/40) of ERT2-Cre+/-; BCL9fl/- mice but none from control cohorts showed signs of disease. Gross pathologic examination of euthanized animals with BCL9 overexpression revealed enlargement of the spleen and LNs. Two distinct patterns of clonal hematological malignancies were identified after detailed histological, IHC and molecular examination. In AID-Cre+/-; BCL9fl/- mice tumors resembled human plasmacytomas (PCs), whereas in ERT2-Cre+/-; BCL9fl/- mice B-cell acute lymphoblastic leukemia (B-ALL). This later result is of particular interest, since BCL9 was first identified by cloning the t(1;14)(q21;q32) translocation from a patient with B-ALL. These findings indicate that BCL9 overexpression at different stages of B-cell development leads to distinct subtypes of B-cell malignancies. Finally, we investigated the BCL9 expression in human extramedullary plasmocytomas (EMP) and B-ALL. 32% of EMP cases analyzed by IHC expressed BCL9 at significant levels. Utilizing gene expression data available in the public domain we also showed that BCL9 is significantly overexpressed in ETV6-RUNX1 and TCF3-PBX1 subtypes of human B-ALL when compared to normal bone marrow counterparts, suggesting that BCL9 may play important roles in the pathogenesis of EMP as well as B-ALL in humans. Since BCL9 is highly expressed in tumors but not in the cells of origin and its interaction with β-catenin is specific, these results imply BCL9 as a promising candidate for targeted therapy. Disclosures No relevant conflicts of interest to declare.

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Depletion of Normal and Malignant B cells with a CD37-specific SMIP molecule

Journal of Clinical Oncology ◽

10.1200/jco.2007.25.18_suppl.3063 ◽

2007 ◽

Vol 25 (18_suppl) ◽

pp. 3063-3063

Author(s):

C. Cerveny ◽

L. Grosmaire ◽

E. Espling ◽

R. Bader ◽

C. Nilsson ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Target Cell ◽

Growth Arrest ◽

Xenograft Model ◽

B Cell Malignancies ◽

B Lymphoma ◽

Anti Tumor Activity

3063 Background: CD37 is a member of the tetraspanin family expressed at high levels by normal mature B cells and by most B cell malignancies. Previously, an antibody to CD37 has been labeled with 131I and tested in clinical trials for therapy of NHL. Treatment with 131I-MB-1, resulted in durable tumor remissions in patients lasting from 4 to 11 months (Press OW, Eary JF, Badger CC, et al. Treatment of refractory non-Hodgkin’s lymphoma with radiolabeled MB-1 (anti-CD37) antibody. J Clin Oncol. 1989;7:1027–1038). Here we assess the functional properties and therapeutic potential of a small modular immunopharmaceutical (SMIP) targeting CD37. Methods: Growth arrest and apoptosis of B lymphoma cell lines was assessed. ADCC activity was evaluated using BJAB targets and human peripheral blood mononuclear cells (PBMC) effectors. Drug-drug interactions were assessed by the Combination Index method. In vivo studies were performed utilizing established human B cell tumor xenografts in nude mice. Results: A CD37-directed SMIP drug candidate mediated growth arrest, apoptosis and ADCC, but not CDC, towards B lymphoma cell lines. The protein showed significant anti-tumor activity in a mouse xenograft model, and selectively depleted normal human B cells in short term cultures of PBMC. When combined with rituximab, the molecule increased apoptosis, C1q binding, and C’ dependent target cell death in vitro, and increased anti-tumor activity in vivo in a xenograft model. Conclusions: In vitro and in vivo characterization of the CD37-targeted SMIP drug suggest a potent capacity to eliminate target cells through combined effects of direct target cell signaling and effector cell recruitment. CD37-mediated growth was synergistic with standard chemotherapies in vitro and showed additive in vivo activity with CD20-targeted therapy. On the basis of these data CD37-directed SMIP therapy is being developed for clinical evaluation against B cell malignancies. No significant financial relationships to disclose.

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KLF4 suppresses transformation of pre-B cells by ABL oncogenes

Blood ◽

10.1182/blood-2006-03-011106 ◽

2006 ◽

Vol 109 (2) ◽

pp. 747-755 ◽

Cited By ~ 49

Author(s):

Michael G. Kharas ◽

Isharat Yusuf ◽

Vanessa M. Scarfone ◽

Vincent W. Yang ◽

Julia A. Segre ◽

...

Keyword(s):

Cell Cycle ◽

B Cells ◽

Tumor Suppressor ◽

B Cell ◽

Cell Activation ◽

Cell Transformation ◽

Cell Lineage ◽

Cell Types ◽

B Cell Malignancies

Abstract Genes that are strongly repressed after B-cell activation are candidates for being inactivated, mutated, or repressed in B-cell malignancies. Krüppel-like factor 4 (Klf4), a gene down-regulated in activated murine B cells, is expressed at low levels in several types of human B-cell lineage lymphomas and leukemias. The human KLF4 gene has been identified as a tumor suppressor gene in colon and gastric cancer; in concordance with this, overexpression of KLF4 can suppress proliferation in several epithelial cell types. Here we investigate the effects of KLF4 on pro/pre–B-cell transformation by v-Abl and BCR-ABL, oncogenes that cause leukemia in mice and humans. We show that overexpression of KLF4 induces arrest and apoptosis in the G1 phase of the cell cycle. KLF4-mediated death, but not cell-cycle arrest, can be rescued by Bcl-XL overexpression. Transformed pro/pre-B cells expressing KLF4 display increased expression of p21CIP and decreased expression of c-Myc and cyclin D2. Tetracycline-inducible expression of KLF4 in B-cell progenitors of transgenic mice blocks transformation by BCR-ABL and depletes leukemic pre-B cells in vivo. Collectively, our work identifies KLF4 as a putative tumor suppressor in B-cell malignancies.

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