Heterogeneous activation of the TGFβ pathway in glioblastomas identified by gene expression-based classification using TGFβ-responsive genes

<p>Abstract</p> <p>Background</p> <p>TGFβ has emerged as an attractive target for the therapeutic intervention of glioblastomas. Aberrant TGFβ overproduction in glioblastoma and other high-grade gliomas has been reported, however, to date, none of these reports has systematically examined the components of TGFβ signaling to gain a comprehensive view of TGFβ activation in large cohorts of human glioma patients.</p> <p>Methods</p> <p>TGFβ activation in mammalian cells leads to a transcriptional program that typically affects 5–10% of the genes in the genome. To systematically examine the status of TGFβ activation in high-grade glial tumors, we compiled a gene set of transcriptional response to TGFβ stimulation from tissue culture and <it>in vivo </it>animal studies. These genes were used to examine the status of TGFβ activation in high-grade gliomas including a large cohort of glioblastomas. Unsupervised and supervised classification analysis was performed in two independent, publicly available glioma microarray datasets.</p> <p>Results</p> <p>Unsupervised and supervised classification using the TGFβ-responsive gene list in two independent glial tumor gene expression data sets revealed various levels of TGFβ activation in these tumors. Among glioblastomas, one of the most devastating human cancers, two subgroups were identified that showed distinct TGFβ activation patterns as measured from transcriptional responses. Approximately 62% of glioblastoma samples analyzed showed strong TGFβ activation, while the rest showed a weak TGFβ transcriptional response.</p> <p>Conclusion</p> <p>Our findings suggest heterogeneous TGFβ activation in glioblastomas, which may cause potential differences in responses to anti-TGFβ therapies in these two distinct subgroups of glioblastomas patients.</p

Inhibition of Transforming Growth Factor ␤ Signaling Reduces Pancreatic Adenocarcinoma Growth and Invasiveness □ S

ABSTRACT Transforming growth factor ␤ (TGF␤) is a pleiotropic factor that regulates cell proliferation, angiogenesis, metastasis, and immune suppression. Dysregulation of the TGF␤ pathway in tumor cells often leads to resistance to the antiproliferative effects of TGF␤ while supporting other cellular processes that promote tumor invasiveness and growth. In the present study, SD-208, a 2,4-disubstituted pteridine, ATP-competitive inhibitor of the TGF␤ receptor I kinase (TGF␤RI), was used to inhibit cellular activities and tumor progression of PANC-1, a human pancreatic tumor line. SD-208 blocked TGF␤-dependent Smad2 phosphorylation and expression of TGF␤-inducible proteins in cell culture. cDNA microarray analysis and functional gene clustering identified groups of TGF␤-regulated genes involved in metastasis, angiogenesis, cell proliferation, survival, and apoptosis. These gene responses were inhibited by SD-208. Using a Boyden chamber motility assay, we demonstrated that SD-208 inhibited TGF␤-stimulated invasion in vitro. An orthotopic xenograft mouse model revealed that SD-208 reduced primary tumor growth and decreased the incidence of metastasis in vivo. Our findings suggest mechanisms through which TGF␤ signaling may promote tumor progression in pancreatic adenocarcinoma. Moreover, they suggest that inhibition of TGF␤RI with a small-molecule inhibitor may be effective as a therapeutic approach to treat human pancreatic cancer

Phase IB Trial of the Anti-Cancer Stem Cell DLL4-Binding Agent Demcizumab with Pemetrexed and Carboplatin as First-Line Treatment of Metastatic Non-Squamous NSCLC

Background: Delta-like ligand 4-Notch (DLL4-Notch) signaling contributes to the maintenance of chemotherapy-resistant cancer stem cells and tumor vasculature. Objective: This phase IB trial of demcizumab, an IgG2 humanized monoclonal antibody directed against DLL4, was undertaken to determine its maximum tolerated dose, safety, immunogenicity, preliminary efficacy, pharmacokinetics, and pharmacodynamics, combined with standard chemotherapy. Patients and Methods: Forty-six treatment-naive patients with metastatic non-squamous non-small cell lung cancer (NSCLC) were enrolled in this open-label, dose-escalation study using a standard 6 + 6 design. Demcizumab (2.5, 5.0, and 7.5 mg/kg) was given once every 3 weeks with standard doses of pemetrexed and carboplatin using a continuous (six cycles followed by demcizumab maintenance) or a truncated demcizumab regimen (four cycles followed by pemetrexed maintenance). Results: Initially, continuous demcizumab was given until progression but two patients developed grade 3 pulmonary hypertension and congestive heart failure after eight or more infusions. Thereafter, 23 patients were treated with a truncated regimen of demcizumab, which was not associated with any grade 3 or greater cardiopulmonary toxicity. Common adverse events were hypertension, raised brain natriuretic peptide, and those expected from carboplatin and pemetrexed alone. Twenty of 40 evaluable patients (50%) had objective tumor responses. In peripheral blood, demcizumab treatment modulated the expression of genes regulating Notch signaling and angiogenesis, and achieved concentrations exceeding those saturating DLL4 binding. Conclusions: This study has identified a truncated dosing regimen and recommended phase II dose of demcizumab (5 mg/kg q3-weekly ×4) for subsequent clinical evaluation in combination with standard carboplatin and pemetrexed chemotherapy. NCT01189968.[Figure not available: see fulltext.