azd-6244 and binimetinib

New treatments for metastatic melanoma work through distinct mechanisms: enhancing the immune response and blocking cellular proliferation. Agents that enhance the immune response include ipilimumab, pembrolizumb, and nivolumab; agents that block cellular proliferation include vemurafenib, dabrafenib, trametinib, cobimetinib, binimetinib, and selumetinib. The translational impact of laboratory discoveries has revolutionized management of metastatic melanoma and enhanced the prognosis of affected patients.

Topics: Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Azetidines; Benzimidazoles; Humans; Imidazoles; Immunologic Factors; Indoles; Ipilimumab; Melanoma; Molecular Targeted Therapy; Nivolumab; Oximes; Piperidines; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Skin Neoplasms; Sulfonamides; Vemurafenib

Topics: Benzimidazoles; Cachexia; Cell Line, Tumor; Enzyme Activation; Humans; Mitogen-Activated Protein Kinases; Neoplasms; Protein Kinase Inhibitors

Pathway inhibition of the RAS-driven MAPK pathway using small-molecule kinase inhibitors has been a key focus for treating cancers driven by oncogenic RAS, yet significant clinical responses are lacking. Feedback reactivation of ERK driven by drug-induced RAF activity has been suggested as one of the major drug resistance mechanisms, especially in the context of oncogenic RAS. To determine whether additional adaptive resistance mechanisms may coexist, we characterized global phosphoproteomic changes after MEK inhibitor selumetinib (AZD6244) treatment in KRAS-mutant A427 and A549 lung adenocarcinoma cell lines employing mass spectrometry-based phosphoproteomics. We identified 9,075 quantifiable unique phosphosites (corresponding to 3,346 unique phosphoproteins), of which 567 phosphosites were more abundant and 512 phosphosites were less abundant after MEK inhibition. Selumetinib increased phosphorylation of KSR-1, a scaffolding protein required for assembly of MAPK signaling complex, as well as altered phosphorylation of GEF-H1, a novel regulator of KSR-1 and implicated in RAS-driven MAPK activation. Moreover, selumetinib reduced inhibitory serine phosphorylation of MET at Ser985 and potentiated HGF- and EGF-induced AKT phosphorylation. These results were recapitulated by pan-RAF (LY3009120), MEK (GDC0623), and ERK (SCH772984) inhibitors, which are currently under early-phase clinical development against RAS-mutant cancers. Our results highlight the unique adaptive changes in MAPK scaffolding proteins (KSR-1, GEF-H1) and in RTK signaling, leading to enhanced PI3K-AKT signaling when the MAPK pathway is inhibited.. This study highlights the unique adaptive changes in MAPK scaffolding proteins (KSR-1, GEF-H1) and in RTK signaling, leading to enhanced PI3K/AKT signaling when the MAPK pathway is inhibited. Mol Cancer Res; 14(10); 1019-29. ©2016 AACR.

Topics: Benzimidazoles; Cell Line, Tumor; Cell Survival; ErbB Receptors; Humans; Lung Neoplasms; Mutation; Phosphoproteins; Phosphorylation; Protein Interaction Maps; Protein Kinase Inhibitors; Proteomics; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-met; Proto-Oncogene Proteins p21(ras); Signal Transduction

KRAS mutations are an established predictor of lack of response to EGFR-targeted therapies in patients with metastatic colorectal cancer (mCRC). However, little is known about the role of the rarer NRAS mutations as a mechanism of primary resistance to the anti-EGFR monoclonal antibody cetuximab in wild-type KRAS mCRC. Using isogenic mCRC cells with a heterozygous knock-in of the NRAS activating mutation Q61K, we aimed to elucidate the mechanism(s) by which mutant NRAS blocks cetuximab from inhibiting mCRC growth. NRASQ61K/+ cells were refractory to cetuximab-induced growth inhibition. Pathway-oriented proteome profiling revealed that cetuximab-unresponsive ERK1/2 phosphorylation was the sole biomarker distinguishing cetuximab-refractory NRASQ61K/+ from cetuximab-sensitive NRAS+/+ cells. We therefore employed four representative MEK1/2 inhibitors (binimetinib, trametinib, selumetinib, and pimasertib) to evaluate the therapeutic value of MEK/ERK signaling in cetuximab-refractory NRAS mutation-induced mCRC. Co-treatment with an ineffective dose of cetuximab augmented, up to more than 1,300-fold, the cytotoxic effects of pimasertib against NRASQ61K/+ cells. Simultaneous combination of MEK1/2 inhibitors with cetuximab resulted in extremely high and dose-dependent synthetic lethal effects, which were executed, at least in part, by exacerbated apoptotic cell death. Dynamic monitoring of real-time cell growth rates confirmed that cetuximab synergistically sensitized NRASQ61K/+ cellsto MEK1/2 inhibition. Our discovery of a synthetic lethal interaction of cetuximab in combination with MEK1/2 inhibition for the NRAS mutant subgroup of mCRC underscores the importance of therapeutic intervention both in the MEK-ERK and EGFR pathways to achieve maximal therapeutic efficacy against NRAS-mutant mCRC tumors.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Benzimidazoles; Cell Line, Tumor; Cell Proliferation; Cetuximab; Colorectal Neoplasms; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Drug Synergism; ErbB Receptors; GTP Phosphohydrolases; Humans; MAP Kinase Kinase 1; MAP Kinase Kinase 2; Membrane Proteins; Mutation; Niacinamide; Phosphorylation; Protein Kinase Inhibitors; Proteomics; Pyridones; Pyrimidinones; Signal Transduction; Transfection

Ovarian cancer is a silent disease with a poor prognosis that urgently requires new therapeutic strategies. In low-grade ovarian tumours, mutations in the MAP3K BRAF gene constitutively activate the downstream kinase MEK. Here we demonstrate that an additional MAP3K, MAP3K8 (TPL-2/COT), accumulates in high-grade serous ovarian carcinomas (HGSCs) and is a potential prognostic marker for these tumours. By combining analyses on HGSC patient cohorts, ovarian cancer cells and patient-derived xenografts, we demonstrate that MAP3K8 controls cancer cell proliferation and migration by regulating key players in G1/S transition and adhesion dynamics. In addition, we show that the MEK pathway is the main pathway involved in mediating MAP3K8 function, and that MAP3K8 exhibits a reliable predictive value for the effectiveness of MEK inhibitor treatment. Our data highlight key roles for MAP3K8 in HGSC and indicate that MEK inhibitors could be a useful treatment strategy, in combination with conventional chemotherapy, for this disease.

Topics: Animals; Antineoplastic Agents; Benzimidazoles; Biomarkers, Tumor; Carcinogenesis; Cell Line, Tumor; Cystadenocarcinoma, Serous; Female; Humans; MAP Kinase Kinase Kinases; MAP Kinase Signaling System; Mice; Mice, Nude; Mitogen-Activated Protein Kinase Kinases; Ovarian Neoplasms; Prognosis; Proto-Oncogene Proteins; Ribosomal Protein S6 Kinases, 90-kDa; Xenograft Model Antitumor Assays

HRAS is a frequently mutated oncogene in cancer. However, mutant HRAS as drug target has not been investigated so far. Here, we show that mutant HRAS hyperactivates the RAS and the mTOR pathway in various cancer cell lines including lung, bladder and esophageal cancer. HRAS mutation sensitized toward growth inhibition by the MEK inhibitors AZD6244, MEK162 and PD0325901. Further, we found that MEK inhibitors induce apoptosis in mutant HRAS cell lines but not in cell lines lacking RAS mutations. In addition, knockdown of HRAS by siRNA blocked cell growth in mutant HRAS cell lines. Inhibition of the PI3K pathway alone or in combination with MEK inhibitors did not alter signaling nor had an impact on viability. However, inhibition of mTOR or combined inhibition of MEK and mTOR reduced cell growth in a synergistic manner. Finally, Ba/F3 cells transformed with mutant HRAS isoforms Q61L, Q61R and G12V demonstrated equal sensitivity towards MEK and mTOR inhibition. Our results show that HRAS mutations in cancer activate the RAS and mTOR pathways which might serve as a therapeutic option for patients with HRAS mutant tumors.

Topics: Animals; Apoptosis; Benzamides; Benzimidazoles; Blotting, Western; Cell Line; Cell Line, Tumor; Cell Proliferation; Cell Transformation, Neoplastic; Diphenylamine; Humans; Mice, SCID; Mitogen-Activated Protein Kinase Kinases; Mutation; Neoplasms; Protein Kinase Inhibitors; Proto-Oncogene Proteins p21(ras); RNA Interference; Signal Transduction; TOR Serine-Threonine Kinases; Tumor Burden; Xenograft Model Antitumor Assays