Significant tumor regressions have been observed in up to 70% of patients receiving adoptively transferred autologous melanoma-reactive tumor infiltrating lymphocytes (TIL) 1,2, and in pilot trials, 40% of treated patients experienced complete regressions of all measurable lesions for at least five years following treatment 3.,To evaluate the potential association between the ability of TIL to mediate durable regressions and their ability to recognize potent antigens that presumably include mutated gene products, a novel screening approach was developed that involved mining whole exome sequence data to identify the mutated proteins that were expressed in patient tumors.,Candidate mutated T cell epitopes that were identified using an MHC binding algorithm 4 were then synthesized and evaluated for recognition by TIL.,Using this approach, mutated antigens expressed on autologous tumor cells were identified as targets of three TIL that were associated with objective tumor regressions following adoptive transfer.,This simplified approach, which avoids the need to generate and laboriously screen cDNA libraries from tumors, may represent a generally applicable method for identifying mutated T cell antigens expressed in melanoma as well as other tumor types.
We describe a mechanism of tumorigenesis mediated by kinase-dead BRAF in the presence of oncogenic RAS.,We show that drugs that selectively inhibit BRAF drive RAS-dependent BRAF binding to CRAF, CRAF activation, and MEK-ERK signaling.,This does not occur when oncogenic BRAF is inhibited, demonstrating that BRAF inhibition per se does not drive pathway activation; it only occurs when BRAF is inhibited in the presence of oncogenic RAS.,Kinase-dead BRAF mimics the effects of the BRAF-selective drugs and kinase-dead Braf and oncogenic Ras cooperate to induce melanoma in mice.,Our data reveal another paradigm of BRAF-mediated signaling that promotes tumor progression.,They highlight the importance of understanding pathway signaling in clinical practice and of genotyping tumors prior to administering BRAF-selective drugs, to identify patients who are likely to respond and also to identify patients who may experience adverse effects.,► BRAF activates ERK but in some circumstances BRAF inhibitors can induce tumor growth ► BRAF inhibitors drive BRAF-CRAF binding, activating ERK in cells with oncogenic RAS ► Kinase-dead mutants of BRAF have the same effect as BRAF inhibitors ► Oncogenic RAS and kinase-dead BRAF cooperate to induce melanoma in mice