Targeted immunotherapy against tumors or angiogenesis has shown promise as an alternative approach for the treatment of malignant disease. Whether or not combining these two treatment modalities would enhance the antitumor effect was tested in mouse models of malignant melanoma. C57BL/6 mice bearing established subcutaneous B16 tumors were treated with anti-vascular endothelial growth factor receptor (anti-VEGFR) fetal liver kinase-1 (Flk-1) monoclonal antibody (mAb) DC101 and/or anti-TYRP-1/gp75 (tyrosinase-related protein-1) mAb TA99. The growth of subcutaneous B16 tumors was significantly suppressed by the mAb DC101 (63%, p<0.001) and by mAb TA99 (75%, p<0.001) treatment alone. The combined antibody (TA99+DC101) treatment resulted in a significant enhancement (93%, p<0.001) of tumor growth suppression. In a B16 pulmonary metastasis model, combined therapy with mAb DC101 and mAb TA99 resulted in a significant reduction of lung metastases compared to the control (p<0.001) and the single agent treatment groups (p<0.05). A combined modality approach that provides passive immunity to melanoma differentiation antigens as well as inhibiting tumor neovascularization may be valuable for the treatment of malignant melanoma.
Mutations in the kinase domain of the epidermal growth factor receptor (EGFR) were identified in approximately 15% of all patients with non-small cell lung cancer (NSCLC). These mutations have been established as an indicator of superior response to gefitinib and erlotinib, small molecule inhibitors of the EGFR kinase domain. Whether these mutations would also render patients more susceptible to treatment with cetuximab (Erbitux), an EGFR-neutralizing antibody, is yet to be determined. In this study, we attempted to evaluate the effect of cetuximab on several NSCLC lines harboring some of the more common EGFR mutations (L858R and delL747-T753insS), as well as the recently identified kinase inhibitor-resistant mutation, T790M. We could show that the kinase activity of the abovementioned EGFR mutants was hindered by cetuximab, as detected by both cell-based phosphorylation and proliferation assays. Interestingly, cetuximab also induced enhanced degradation of the EGFR mutants as compared with the wild-type receptor. Most importantly, cetuximab successfully inhibited the growth of NSCLC lines in xenograft models. These results indicate the promising potential of cetuximab as a regimen for patients with NSCLC bearing these mutations.
Supplementary Figure 3 from Therapeutic Implications of a Human Neutralizing Antibody to the Macrophage-Stimulating Protein Receptor Tyrosine Kinase (RON), a c-MET Family Member
Supplementary Figure 7A and 7B from Therapeutic Implications of a Human Neutralizing Antibody to the Macrophage-Stimulating Protein Receptor Tyrosine Kinase (RON), a c-MET Family Member
Supplementary Figure 4 from Therapeutic Implications of a Human Neutralizing Antibody to the Macrophage-Stimulating Protein Receptor Tyrosine Kinase (RON), a c-MET Family Member
The vascular endothelial growth factor (VEGF) receptor fetal liver kinase 1 (flk1; VEGFR-2, KDR) is an endothelial cell–specific receptor tyrosine kinase that mediates physiological and pathological angiogenesis. We hypothesized that an active immunotherapy approach targeting flk1 may inhibit tumor angiogenesis and metastasis. To test this hypothesis, we first evaluated whether immune responses to flk1 could be elicited in mice by immunization with dendritic cells pulsed with a soluble flk1 protein (DC-flk1). This immunization generated flk1-specific neutralizing antibody and CD8+ cytotoxic T cell responses, breaking tolerance to self-flk1 antigen. Tumor-induced angiogenesis was suppressed in immunized mice as measured in an alginate bead assay. Development of pulmonary metastases was strongly inhibited in DC-flk1–immunized mice challenged with B16 melanoma or Lewis lung carcinoma cells. DC-flk1 immunization also significantly prolonged the survival of mice challenged with Lewis lung tumors. Thus, an active immunization strategy that targets an angiogenesis-related antigen on endothelium can inhibit angiogenesis and may be a useful approach for treating angiogenesis-related diseases.
To establish whether cetuximab, a chimeric IgG1 antibody targeting epidermal growth factor receptor, has the potential to restore responsiveness to oxaliplatin in preclinical cancer models, as has been shown with irinotecan in irinotecan refractory metastatic colorectal cancer patients.The effects of cetuximab and oxaliplatin, alone or in combination, were tested in vitro and in vivo using human colorectal cancer cell lines selected for oxaliplatin resistance, as well as parental control cell lines. Evaluations were made of subcutaneous xenograft tumor growth in nu/nu athymic mice, as well as activation of mitogen-activated protein kinase (extracellular signal-regulated kinase 1/2) and AKT, expression of DNA repair genes, density of apurinic/apyrimidinic DNA damage, and accumulation of platinum-DNA adducts in vitro.Oxaliplatin + cetuximab efficacy in murine subcutaneous xenograft models was greater than that of monotherapies and independent of the responsiveness to oxaliplatin monotherapy. In vitro, cetuximab reduced expression of excision repair cross-complementation group 1 and XPF, which are key components of the nucleotide excision repair pathway involved in the excision of platinum-DNA adducts. In addition, cetuximab reduced expression of XRCC1, a component of the base excision repair pathway responsible for the repair of apurinic/apyrimidinic sites. Effects of cetuximab on DNA repair protein levels were downstream to effects on mitogen-activated protein kinase and AKT pathway activation. In line with effects on DNA repair protein expression, cetuximab increased the accumulation of platinum and apurinic/apyrimidinic sites on DNA during oxaliplatin treatment.Cetuximab has the potential to salvage the benefits of oxaliplatin in oxaliplatin-resistant colorectal cancer patients by reducing DNA repair capacity.
<div>Abstract<p><b>Purpose:</b> Transforming growth factor β (TGFβ) is a pleiotropic cytokine that affects tumor growth, metastasis, stroma, and immune response. We investigated the therapeutic efficacy of anti–TGFβ receptor II (TGFβ RII) antibody in controlling metastasis and tumor growth as well as enhancing antitumor immunity in preclinical tumor models.</p><p><b>Experimental Design:</b> We generated neutralizing antibodies to TGFβ RII and assessed the antibody effects on cancer, stroma, and immune cells <i>in vitro</i>. The efficacy and mechanism of action of the antibody as monotherapy and in combination with chemotherapy in suppression of primary tumor growth and metastasis were evaluated in several tumor models.</p><p><b>Results:</b> Anti–TGFβ RII antibody blocked TGFβ RII binding to TGFβ 1, 2, and 3, and attenuated the TGFβ-mediated activation of downstream Smad2 kinase, invasion of cancer cells, motility of endothelial and fibroblast cells, and induction of immunosuppressive cells. Treatment with the antibody significantly suppressed primary tumor growth and metastasis and enhanced natural killer and CTL activity in tumor-bearing mice. Immunohistochemistry analysis showed cancer cell apoptosis and massive necrosis, and increased tumor-infiltrating T effector cells and decreased tumor-infiltrating Gr-1+ myeloid cells in the antibody-treated tumors. Fluorescence-activated cell sorting analysis indicated the significant reduction of peripheral Gr-1+/CD11b+ myeloid cells in treated animals. Concomitant treatment with the cytotoxic agent cyclophosphamide resulted in a significantly increased antitumor efficacy against primary tumor growth and metastasis.</p><p><b>Conclusions:</b> These preclinical data provide a foundation to support using anti–TGFβ RII antibody as a therapeutic agent for TGFβ RII–dependent cancer with metastatic capacity. Clin Cancer Res; 16(4); 1191–205</p></div>
652 The epidermal growth factor receptor (EGFR) and insulin-like growth factor 1 receptor (IGF-1R) pathways play an important role in growth and survival of pancreatic tumor cells. We have previously demonstrated the efficacy of the fully human IgG1 anti-EGFR mAb cetuximab in combination with gemcitabine in preclinical models of pancreatic carcinoma. In this study, we studied the antitumor activity of the human IgG1 anti-IGF-1R mAb IMC-A12 when combined with cetuximab + gemcitabine in human pancreatic tumor xenograft models. Mice bearing established BxPC-3, L3.7pL, or MiaPaCa-2 pancreatic xenografts were treated with 1) IMC-A12 (40mg/kg, i.p., 3x/week), 2) cetuximab (40mg/kg, i.p., 3x/week), 3) gemcitabine (150mg/kg, i.p., q7d), 4) cetuximab + gemcitabine, or 5) IMC-A12 + cetuximab + gemcitabine. IMC-A12 had significant efficacy in BxPC-3 and MiaPaCa-2 (T/C% = 41% and 37%, respectively) but minimal efficacy in the L3.7pL model (T/C% = 91%). Cetuximab + gemcitabine therapy had significant efficacy in all three models (T/C% = 17%, 23%, and 46% for BxPC-3, L3.7pL, and MiaPaCa-2, respectively). Adding IMC-A12 to cetuximab + gemcitabine therapy significantly increased the anti-tumor effects (P
Transforming growth factor beta (TGF \#946;) is a pleiotropic cytokine that profoundly regulates the pathogenesis of cancer and metastasis. TGF \#946; stimulates activation of TGF \#946; receptor I kinase and downstream signaling cascades that initiate broad cellular and non cellular processes i.e. survival, proliferation and differentiation, migration and motility, and deposition of the extracellular matrix and induction of cytokines contributing to tumorigenesis, metastasis, angiogenesis, and inflammation during tumor progression. Myeloid cells have been reported to be an important mediator in promoting metastasis and angiogenesis, suppressing immunity against tumor and inducing anti-VEGF resistant tumors. Therefore, targeting this multifunctional cell population will be beneficial for enhancement of antitumor therapeutic efficacy. The binding of TGF \#946; ligands to TGF \#946; receptor II (TGF \#946; RII) is one crucial step to initiate the activation of TGF \#946; signaling pathways. Here, we report that we have developed high affinity monoclonal antibodies with specific blocking activity to TGF \#946; R II binding to TGF \#946; ligands. By using the antibodies, we investigated the mechanism of actions of TGF \#946; mediated activity in promoting cancer cell invasiveness, angiogenesis and the role of Gr-1/CD11b+ myeloid cells in tumor progression and evaluated the therapeutic efficacy of anti-TGF \#946; R II antibodies in suppression of tumor growth and metastasis. Data on cell-based assays displayed the capacity of anti-TGF \#946; R II antibodies in inhibiting TGF \#946; receptor mediated signaling cascades and cellular biological functions in vitro. In vivo studies demonstrated that treatment of tumor bearing mice with the anti-TGF \#946; R II antibodies resulted in suppression of primary tumor growth and metastasis in conjunction with the blockade of cancer cell invasion and VEGF-A secretion, the inhibition of myeloid cell function and the depletion of Gr-1/CD11b/TGF \#946; R II+ myeloid cells. Most importantly, we have for first time revealed that a subset of TGF \#946; R II+ myeloid cells has a major role in promoting tumor growth and metastasis through inducing tumor cell migration and inhibiting cellular immune response. Thus, this study has provided a foundation supporting that anti-TGF \#946; R II antibody mediated abrogation of TGF \#946; R II+ myeloid cells would be an effective approach to controlling the deleterious activity of myeloid cell in cancer, and anti-TGF \#946; RII antibody-based therapeutics may represent a novel strategy for treatment of cancer, particularly for metastatic tumors. Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 844.
