title: BRAF inhibition increases tumor infiltration by T cells and enhances the antitumor activity of adoptive immunotherapy in mice.
abstract: OBJECTIVE
  Treatment of melanoma patients with selective BRAF inhibitors results in objective clinical responses in the majority of patients with BRAF-mutant tumors. However, resistance to these inhibitors develops within a few months. In this study, we test the hypothesis that BRAF inhibition in combination with adoptive T-cell transfer (ACT) will be more effective at inducing long-term clinical regressions of BRAF-mutant tumors.
  
  
  METHODS
  BRAF-mutated human melanoma tumor cell lines transduced to express gp100 and H-2D(b) to allow recognition by gp100-specific pmel-1 T cells were used as xenograft models to assess melanocyte differentiation antigen-independent enhancement of immune responses by BRAF inhibitor PLX4720. Luciferase-expressing pmel-1 T cells were generated to monitor T-cell migration in vivo. The expression of VEGF was determined by ELISA, protein array, and immunohistochemistry. Importantly, VEGF expression after BRAF inhibition was tested in a set of patient samples.
  
  
  RESULTS
  We found that administration of PLX4720 significantly increased tumor infiltration of adoptively transferred T cells in vivo and enhanced the antitumor activity of ACT. This increased T-cell infiltration was primarily mediated by the ability of PLX4720 to inhibit melanoma tumor cell production of VEGF by reducing the binding of c-myc to the VEGF promoter. Furthermore, analysis of human melanoma patient tumor biopsies before and during BRAF inhibitor treatment showed downregulation of VEGF consistent with the preclinical murine model.
  
  
  CONCLUSIONS
  These findings provide a strong rationale to evaluate the potential clinical application of combining BRAF inhibition with T-cell-based immunotherapy for the treatment of patients with melanoma.
authors.affiliation: Departments of Melanoma Medical Oncology and Immunology, Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Chengwen
authors.initials: C
authors.lastname: Liu
authors.forename: Weiyi
authors.initials: W
authors.lastname: Peng
authors.forename: Chunyu
authors.initials: C
authors.lastname: Xu
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Lou
authors.forename: Minying
authors.initials: M
authors.lastname: Zhang
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Wargo
authors.forename: Jie Qing
authors.initials: JQ
authors.lastname: Chen
authors.forename: Haiyan S
authors.initials: HS
authors.lastname: Li
authors.forename: Stephanie S
authors.initials: SS
authors.lastname: Watowich
authors.forename: Yan
authors.initials: Y
authors.lastname: Yang
authors.forename: Dennie
authors.initials: D
authors.lastname: Tompers Frederick
authors.forename: Zachary A
authors.initials: ZA
authors.lastname: Cooper
authors.forename: Rina M
authors.initials: RM
authors.lastname: Mbofung
authors.forename: Mayra
authors.initials: M
authors.lastname: Whittington
authors.forename: Keith T
authors.initials: KT
authors.lastname: Flaherty
authors.forename: Scott E
authors.initials: SE
authors.lastname: Woodman
authors.forename: Michael A
authors.initials: MA
authors.lastname: Davies
authors.forename: Laszlo G
authors.initials: LG
authors.lastname: Radvanyi
authors.forename: Willem W
authors.initials: WW
authors.lastname: Overwijk
authors.forename: Gregory
authors.initials: G
authors.lastname: Lizée
authors.forename: Patrick
authors.initials: P
authors.lastname: Hwu
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D016219:Immunotherapy, Adoptive; D007211:Indoles / Q000008:administration & dosage / Q000494:pharmacology; D016246:Lymphocytes, Tumor-Infiltrating / Q000187:drug effects / Q000276:immunology*; D008545:Melanoma / Q000235:genetics / Q000276:immunology* / Q000628:therapy; D051379:Mice; D009154:Mutation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D048493:Proto-Oncogene Proteins B-raf / Q000037:antagonists & inhibitors* / Q000235:genetics; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D013449:Sulfonamides / Q000008:administration & dosage / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
chemical_list: D007211:Indoles; C528407:PLX 4720; D047428:Protein Kinase Inhibitors; D016271:Proto-Oncogene Proteins c-myc; D013449:Sulfonamides; D042461:Vascular Endothelial Growth Factor A; D048493:Proto-Oncogene Proteins B-raf