azd-1480 and Brain-Neoplasms

The mTOR signaling is dysregulated prominently in human cancers including glioblastoma, suggesting mTOR as a robust target for therapy. Inhibitors of mTOR have had limited success clinically, however, in part because their mechanism of action is cytostatic rather than cytotoxic. Here, we tested three distinct mTOR kinase inhibitors (TORKi) PP242, KU-0063794, and sapanisertib against glioblastoma cells. All agents similarly decreased proliferation of glioblastoma cells, whereas PP242 uniquely induced apoptosis. Apoptosis induced by PP242 resulted from off-target cooperative inhibition of JAK2 and protein kinase C alpha (PKCα). Induction of apoptosis was also decreased by additional on-target inhibition of mTOR, due to induction of autophagy. As EGFR inhibitors can block PKCα, EGFR inhibitors erlotinib and osimertinib were tested separately in combination with the JAK2 inhibitor AZD1480. Combination therapy induced apoptosis of glioblastoma tumors in both flank and in patient-derived orthotopic xenograft models, providing a preclinical rationale to test analogous combinations in patients. SIGNIFICANCE: These findings identify PKCα and JAK2 as targets that drive apoptosis in glioblastoma, potentially representing a clinically translatable approach for glioblastoma.

Topics: Acrylamides; Aniline Compounds; Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Autophagy; Brain Neoplasms; Cell Line, Tumor; ErbB Receptors; Erlotinib Hydrochloride; Female; Glioblastoma; Humans; Indoles; Janus Kinase 2; Mice; Morpholines; Protein Kinase C-alpha; Protein Kinase Inhibitors; Purines; Pyrazoles; Pyrimidines; Signal Transduction; TOR Serine-Threonine Kinases; Xenograft Model Antitumor Assays

Determining the mechanism of treatment failure of VEGF signaling inhibitors for malignant glioma patients would provide insight into approaches to overcome therapeutic resistance. In this study, we demonstrate that human glioblastoma tumors failing bevacizumab have an increase in the mean percentage of p-STAT3-expressing cells compared to samples taken from patients failing non-antiangiogenic therapy containing regimens. Likewise, in murine xenograft models of glioblastoma, the mean percentage of p-STAT3-expressing cells in the gliomas resistant to antiangiogenic therapy was markedly elevated relative to controls. Administration of the JAK/STAT3 inhibitor AZD1480 alone and in combination with cediranib reduced tumor hypoxia and the infiltration of VEGF inhibitor-induced p-STAT3 macrophages. Thus, the combination of AZD1480 with cediranib markedly reduced tumor volume, and microvascular density, indicating that up regulation of the STAT3 pathway can mediate resistance to antiangiogenic therapy and combinational approaches may delay or overcome resistance.

Topics: Angiogenesis Inhibitors; Animals; Antibodies, Monoclonal, Humanized; Antineoplastic Combined Chemotherapy Protocols; Bevacizumab; Brain Neoplasms; Cell Hypoxia; Cell Line, Tumor; Disease Models, Animal; Drug Interactions; Female; Glioblastoma; Humans; Immunohistochemistry; Intermediate Filament Proteins; Macrophages; Mice; Mice, Inbred C57BL; Mice, Nude; Nerve Tissue Proteins; Nestin; Pyrazoles; Pyrimidines; Quinazolines; Signal Transduction; STAT3 Transcription Factor; Xenograft Model Antitumor Assays

Aberrant activation of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway has been implicated in glioblastoma (GBM) progression. To develop a therapeutic strategy to inhibit STAT-3 signaling, we have evaluated the effects of AZD1480, a pharmacologic inhibitor of JAK1 and JAK2. In this study, the in vitro efficacy of AZD1480 was tested in human and murine glioma cell lines. AZD1480 treatment effectively blocks constitutive and stimulus-induced JAK1, JAK2, and STAT-3 phosphorylation in both human and murine glioma cells, and leads to a decrease in cell proliferation and induction of apoptosis. Furthermore, we used human xenograft GBM samples as models for the study of JAK/STAT-3 signaling in vivo, because human GBM samples propagated as xenografts in nude mice retain both the hallmark genetic alterations and the invasive phenotype seen in vivo. In these xenograft tumors, JAK2 and STAT-3 are constitutively active, but levels vary among tumors, which is consistent with the heterogeneity of GBMs. AZD1480 inhibits constitutive and stimulus-induced phosphorylation of JAK2 and STAT-3 in these GBM xenograft tumors in vitro, downstream gene expression, and inhibits cell proliferation. Furthermore, AZD1480 suppresses STAT-3 activation in the glioma-initiating cell population in GBM tumors. In vivo, AZD1480 inhibits the growth of subcutaneous tumors and increases survival of mice bearing intracranial GBM tumors by inhibiting STAT-3 activity, indicating that pharmacologic inhibition of the JAK/STAT-3 pathway by AZD1480 should be considered for study in the treatment of patients with GBM tumors.

Topics: Animals; Antineoplastic Agents; Brain Neoplasms; Cell Line, Tumor; Enzyme Activation; Female; Glioblastoma; Humans; Janus Kinase 2; Mice; Mice, Inbred C57BL; Mice, Nude; Pyrazoles; Pyrimidines; STAT3 Transcription Factor; Xenograft Model Antitumor Assays