n-(3-4-difluoro-2-(2-fluoro-4-iodophenylamino)-6-methoxyphenyl)-1-(2-3-dihydroxypropyl)cyclopropane-1-sulfonamide and Colorectal-Neoplasms

Molecular mechanisms driving acquired resistance to anti-EGFR therapies in metastatic colorectal cancer (mCRC) are complex but generally involve the activation of the downstream RAS-RAF-MEK-MAPK pathway. Nevertheless, even if inhibition of EGFR and MEK could be a strategy for overcoming anti-EGFR resistance, its use is limited by the development of MEK inhibitor (MEKi) resistance.. We have generated in vitro and in vivo different CRC models in order to underline the mechanisms of MEKi resistance.. The three different in vitro MEKi resistant models, two generated by human CRC cells quadruple wild type for KRAS, NRAS, BRAF, PI3KCA genes (SW48-MR and LIM1215-MR) and one by human CRC cells harboring KRAS mutation (HCT116-MR) showed features related to the gene signature of colorectal cancer CMS4 with up-regulation of immune pathway as confirmed by microarray and western blot analysis. In particular, the MEKi phenotype was associated with the loss of epithelial features and acquisition of mesenchymal markers and morphology. The change in morphology was accompanied by up-regulation of PD-L1 expression and activation of EGFR and its downstream pathway, independently to RAS mutation status. To extend these in vitro findings, we have obtained mouse colon cancer MC38- and CT26-MEKi resistant syngeneic models (MC38-MR and CT26-MR). Combined treatment with MEKi, EGFR inhibitor (EGFRi) and PD-L1 inhibitor (PD-L1i) resulted in a marked inhibition of tumor growth in both models.. These results suggest a strategy to potentially improve the efficacy of MEK inhibition by co-treatment with EGFR and PD-L1 inhibitors via modulation of host immune responses.

Topics: Antibodies, Monoclonal; B7-H1 Antigen; Cell Line, Tumor; Colorectal Neoplasms; Diphenylamine; Drug Resistance, Neoplasm; Epithelial-Mesenchymal Transition; ErbB Receptors; Erlotinib Hydrochloride; Female; HCT116 Cells; Humans; MAP Kinase Kinase Kinases; MAP Kinase Signaling System; Sulfonamides; Treatment Outcome; Xenograft Model Antitumor Assays

Although MEK blockade has been highlighted as a promising antitumor drug, it has poor clinical efficacy in KRAS mutant colorectal cancer (CRC). Several feedback systems have been described in which inhibition of one intracellular pathway leads to activation of a parallel signaling pathway, thereby decreasing the effectiveness of single-MEK targeted therapies. Here, we investigated a bypass mechanism of resistance to MEK inhibition in KRAS CRC. We found that KRAS mutant CRC cells with refametinib, MEK inhibitor, induced MIF secretion and resulted in activation of STAT3 and MAPK. MIF knockdown by siRNA restored sensitivity to refametinib in KRAS mutant cells. In addition, combination with refametinib and 4-IPP, a MIF inhibitor, effectively reduced the activity of STAT3 and MAPK, more than single-agent treatment. As a result, combined therapy was found to exhibit a synergistic growth inhibitory effect against refametinib-resistant cells by inhibition of MIF activation. These results reveal that MIF-induced STAT3 and MAPK activation evoked an intrinsic resistance to refametinib. Our results provide the basis for a rational combination strategy against KRAS mutant colorectal cancers, predicated on the understanding of cross talk between the MEK and MIF pathways.

Topics: Apoptosis; Cell Line, Tumor; Colorectal Neoplasms; Diphenylamine; Drug Resistance, Neoplasm; Humans; Intramolecular Oxidoreductases; Macrophage Migration-Inhibitory Factors; MAP Kinase Signaling System; Mitogen-Activated Protein Kinases; Mutation; Protein Kinase Inhibitors; Proto-Oncogene Proteins p21(ras); RNA Interference; RNA, Small Interfering; Sulfonamides

The use of cetuximab in the treatment of metastatic colorectal cancer is limited by development of resistance.. We have investigated in three models of highly epidermal growth factor receptor (EGFR)-dependent colorectal cancer xenografts, the effect of maintenance therapy with different kinase inhibitors alone or in combination with cetuximab, after cytotoxic treatment induction with irinotecan plus cetuximab.. SW48, LIM 1215, and GEO colorectal cancer cell lines were engrafted into nude mice and treated for 3 weeks with irinotecan and/or cetuximab. The combined treatment induced a significant reduction of tumor size. A subsequent experiment was performed in all three xenograft models in which after an induction treatment with irinotecan plus cetuximab, mice were randomly assigned to one of the following treatments: control, cetuximab, regorafenib, a selective PIK3CA inhibitor (PIK3CAi), a selective MEK inhibitor (MEKi), and/or the combination of each inhibitor with cetuximab. The cetuximab plus MEKi treatment determined the best antitumor activity with suppression of tumor growth. This effect was prolonged for 13 to 15 weeks after cessation of therapy and was accompanied by prolonged survival. Antitumor activity was accompanied by inhibition of the MAPK and MEK pathways. Moreover, in the cetuximab plus MEKi-treated SW48 xenograft group, KRAS mutations as a mechanism of acquired resistance were detected in 25% of cases compared with 75% KRAS mutations in the MEKi-treated group.. A possible strategy to prevent and/or overcome resistance to anti-EGFR inhibitors in metastatic colorectal cancer is a maintenance therapy with cetuximab plus MEKi after an initial treatment with irinotecan plus cetuximab.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Camptothecin; Cell Line, Tumor; Cell Survival; Cetuximab; Class I Phosphatidylinositol 3-Kinases; Colorectal Neoplasms; Diphenylamine; Drug Synergism; ErbB Receptors; Female; Humans; Irinotecan; MAP Kinase Kinase Kinases; MAP Kinase Signaling System; Mice; Mice, Inbred BALB C; Mice, Nude; Mutation; Phosphatidylinositol 3-Kinases; Sulfonamides; Xenograft Model Antitumor Assays

Circulating tumor DNA (ctDNA) is a promising biomarker in cancer.. We generated xenograft models of cancer and detected ctDNA in plasma by qRCR targeting human AluJ sequences.. Our assay reached single cell sensitivity in vitro and a correlation between ctDNA amount and tumor size was observed in vivo. Treatment with a mitogen activated protein kinase kinase (MEK)-inhibitor (BAY 869766) reduced ctDNA levels. Using this assay, we also confirmed that high levels of cell-free DNA are found in cancer patients compared to healthy individuals.. We show that ctDNA may be useful biomarker for monitoring tumor growth and treatment response.

Topics: Animals; Antineoplastic Agents; Biomarkers, Tumor; Breast Neoplasms; Case-Control Studies; Cell Line, Tumor; Colorectal Neoplasms; Diphenylamine; DNA; Female; Humans; Kinetics; Male; Mice; Mice, Nude; Real-Time Polymerase Chain Reaction; Reference Standards; Sulfonamides; Tumor Burden; Xenograft Model Antitumor Assays