title: HLA class I downregulation is associated with enhanced NK-cell killing of melanoma cells with acquired drug resistance to BRAF inhibitors.
abstract: The frequent development of drug resistance to targeted therapies in cancer patients has stimulated interest in strategies counteracting resistance. Combining immunotherapies with targeted therapies is one such strategy. In this context, we asked whether human NK cells can target melanoma cells that have acquired resistance to selective inhibitors targeting activating mutants of the B-Raf kinase (BRAF inhibitors, BRAFi). We generated drug-resistant cell variants in vitro from human BRAF-mutant melanoma cell lines MEL-HO, COLO-38, SK-MEL-37, 1520 and from primary melanoma cells freshly isolated from two patients. All drug-resistant cell variants remained susceptible to lysis by IL-2-activated NK cells; and two BRAFi-resistant lines (BRAFi-R) became significantly more susceptible to NK-cell lysis than their parental lines. This was associated with significant HLA class I antigen downregulation and PD-L1 upregulation on the drug-resistant lines. Although blocking HLA class I enhanced the extent of lysis of both BRAFi-R and parental cells to NK-cell-mediated lysis, antibody-mediated inhibition of PD1-PD-L1 interactions had no detectable effect. HLA class I antigen expression on BRAFi-R melanoma variants thus appears to play a major role in their susceptibility to NK-cell cytotoxicity. These findings suggest that NK-cell-based immunotherapy may be a viable approach to treat melanoma patients with acquired resistance to BRAF inhibitors.
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden.|University Magna Graecia of Catanzaro, Catanzaro, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Sottile
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden.|University Magna Graecia of Catanzaro, Catanzaro, Italy.
authors.forename: Pradeepa N
authors.initials: PN
authors.lastname: Pangigadde
authors.affiliation: Department of Obstetrics and Gynaecology, University of Cambridge School of Clinical Medicine, NIHR Cambridge Biomedical Research Centre, Cambridge, UK.
authors.forename: Thomas
authors.initials: T
authors.lastname: Tan
authors.affiliation: Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Anichini
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Francesco
authors.initials: F
authors.lastname: Sabbatino
authors.affiliation: University Magna Graecia of Catanzaro, Catanzaro, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Trecroci
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Elvira
authors.initials: E
authors.lastname: Favoino
authors.affiliation: Department of Obstetrics and Gynaecology, University of Cambridge School of Clinical Medicine, NIHR Cambridge Biomedical Research Centre, Cambridge, UK.
authors.forename: Laura
authors.initials: L
authors.lastname: Orgiano
authors.affiliation: Department of Obstetrics and Gynaecology, University of Cambridge School of Clinical Medicine, NIHR Cambridge Biomedical Research Centre, Cambridge, UK.
authors.forename: James
authors.initials: J
authors.lastname: Roberts
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Soldano
authors.initials: S
authors.lastname: Ferrone
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden.
authors.forename: Klas
authors.initials: K
authors.lastname: Kärre
authors.affiliation: Department of Obstetrics and Gynaecology, University of Cambridge School of Clinical Medicine, NIHR Cambridge Biomedical Research Centre, Cambridge, UK.
authors.forename: Francesco
authors.initials: F
authors.lastname: Colucci
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden.|University Magna Graecia of Catanzaro, Catanzaro, Italy.
authors.forename: Ennio
authors.initials: E
authors.lastname: Carbone
mesh_terms: D060890:B7-H1 Antigen / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D003602:Cytotoxicity, Immunologic; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm; D015234:HLA-A Antigens / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007093:Imidazoles / Q000008:administration & dosage / Q000494:pharmacology; D016219:Immunotherapy, Adoptive / Q000379:methods*; D007376:Interleukin-2 / Q000378:metabolism*; D007694:Killer Cells, Natural / Q000276:immunology*; D008213:Lymphocyte Activation; D008545:Melanoma / Q000276:immunology / Q000628:therapy*; D010091:Oximes / Q000008:administration & dosage / Q000494:pharmacology; D048493:Proto-Oncogene Proteins B-raf / Q000037:antagonists & inhibitors; D015854:Up-Regulation
chemical_list: D060890:B7-H1 Antigen; D015234:HLA-A Antigens; D007093:Imidazoles; D007376:Interleukin-2; D010091:Oximes; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; C561627:dabrafenib
keywords: NK cell; acquired drug resistance; combination therapy; cytotoxicity; melanoma HLA