title: BRAF- and MEK-Targeted Small Molecule Inhibitors Exert Enhanced Antimelanoma Effects in Combination With Oncolytic Reovirus Through ER Stress.
abstract: Reovirus type 3 (Dearing) (RT3D) infection is selective for cells harboring a mutated/activated RAS pathway. Therefore, in a panel of melanoma cell lines (including RAS mutant, BRAF mutant and RAS/BRAF wild-type), we assessed therapeutic combinations that enhance/suppress ERK1/2 signaling through use of BRAF/MEK inhibitors. In RAS mutant cells, the combination of RT3D with the BRAF inhibitor PLX4720 (paradoxically increasing ERK1/2 signaling in this context) did not enhance reoviral cytotoxicity. Instead, and somewhat surprisingly, RT3D and BRAF inhibition led to enhanced cell kill in BRAF mutated cell lines. Likewise, ERK1/2 inhibition, using the MEK inhibitor PD184352, in combination with RT3D resulted in enhanced cell kill in the entire panel. Interestingly, TCID50 assays showed that BRAF and MEK inhibitors did not affect viral replication. Instead, enhanced efficacy was mediated through ER stress-induced apoptosis, induced by the combination of ERK1/2 inhibition and reovirus infection. In vivo, combined treatments of RT3D and PLX4720 showed significantly increased activity in BRAF mutant tumors in both immune-deficient and immune-competent models. These data provide a strong rationale for clinical translation of strategies in which RT3D is combined with BRAF inhibitors (in BRAF mutant melanoma) and/or MEK inhibitors (in BRAF and RAS mutant melanoma).
authors.affiliation: Targeted Therapy Team, The Institute of Cancer Research, London, UK.
authors.forename: Victoria
authors.initials: V
authors.lastname: Roulstone
authors.affiliation: Targeted Therapy Team, The Institute of Cancer Research, London, UK.
authors.forename: Malin
authors.initials: M
authors.lastname: Pedersen
authors.affiliation: Targeted Therapy Team, The Institute of Cancer Research, London, UK.
authors.forename: Joan
authors.initials: J
authors.lastname: Kyula
authors.affiliation: Targeted Therapy Team, The Institute of Cancer Research, London, UK.
authors.forename: David
authors.initials: D
authors.lastname: Mansfield
authors.affiliation: Targeted Therapy Team, The Institute of Cancer Research, London, UK.
authors.forename: Aadil A
authors.initials: AA
authors.lastname: Khan
authors.affiliation: Targeted Therapy Team, The Institute of Cancer Research, London, UK.
authors.forename: Grainne
authors.initials: G
authors.lastname: McEntee
authors.affiliation: Targeted Therapy Team, The Institute of Cancer Research, London, UK.
authors.forename: Michelle
authors.initials: M
authors.lastname: Wilkinson
authors.affiliation: Targeted Therapy Team, The Institute of Cancer Research, London, UK.
authors.forename: Eleni
authors.initials: E
authors.lastname: Karapanagiotou
authors.affiliation: Oncolytics Biotech. Inc., Calgary, Alberta, Canada.
authors.forename: Matt
authors.initials: M
authors.lastname: Coffey
authors.affiliation: Cancer Research UK Manchester Institute, Manchester, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Marais
authors.affiliation: Leeds Institute of Molecular Medicine, Leeds, UK.
authors.forename: Adel
authors.initials: A
authors.lastname: Jebar
authors.affiliation: Leeds Institute of Molecular Medicine, Leeds, UK.
authors.forename: Fiona
authors.initials: F
authors.lastname: Errington-Mais
authors.affiliation: Leeds Institute of Molecular Medicine, Leeds, UK.
authors.forename: Alan
authors.initials: A
authors.lastname: Melcher
authors.affiliation: Molecular Medicine Program, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Vile
authors.affiliation: University of Surrey, Guildford, UK.
authors.forename: Hardev
authors.initials: H
authors.lastname: Pandha
authors.affiliation: Targeted Therapy Team, The Institute of Cancer Research, London, UK.
authors.forename: Martin
authors.initials: M
authors.lastname: McLaughlin
authors.affiliation: Targeted Therapy Team, The Institute of Cancer Research, London, UK. Electronic address: Kevin.Harrington@icr.ac.uk.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Harrington
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001549:Benzamides / Q000008:administration & dosage / Q000494:pharmacology; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D004195:Disease Models, Animal; D019008:Drug Resistance, Neoplasm; D059865:Endoplasmic Reticulum Stress; D004789:Enzyme Activation; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007211:Indoles / Q000008:administration & dosage / Q000494:pharmacology; D008545:Melanoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D015689:Oncogene Protein p21(ras) / Q000235:genetics; D050130:Oncolytic Virotherapy; D050504:Oncolytic Viruses; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D048493:Proto-Oncogene Proteins B-raf / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D012087:Reoviridae / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects; D013449:Sulfonamides / Q000008:administration & dosage / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
chemical_list: C120227:2-(2-chloro-4-iodophenylamino)-N-cyclopropylmethoxy-3,4-difluorobenzamide; D000970:Antineoplastic Agents; D001549:Benzamides; D007211:Indoles; C528407:PLX 4720; D047428:Protein Kinase Inhibitors; D013449:Sulfonamides; D014409:Tumor Necrosis Factor-alpha; D048493:Proto-Oncogene Proteins B-raf; D020928:Mitogen-Activated Protein Kinases; D020169:Caspases; D015689:Oncogene Protein p21(ras)