The detection of V600E BRAF mutations has fundamental clinical consequences as the treatment option with BRAF inhibitors such as vemurafenib or dabrafenib yields response rates of ∼48%.,Heterogeneity with respect to BRAF mutation in different metastases has been described in single cases.,As this has important implications for the determination of BRAF status and treatment of patients, it is essential to acquire more data.,A total of 300 tumour samples from 187 melanoma patients were analysed for BRAF mutations by pyrosequencing.,Equivocal results were confirmed by capillary sequencing.,Clinical data with respect to melanoma type, tumour site and survival were summarised for 53 patients with multiple analysed tumour samples (2-13 per patient).,BRAF mutations were found in 84 patients (44.9%) and 144 tumour samples (48%) with BRAF mutations in 45.5% of primary tumours and 51.3% of metastases, respectively.,In 10 out of 53 patients (18.9%) where multiple samples were analysed results were discordant with respect to mutation findings with wild-type and mutated tumours in the same patient.,Mutations did not appear more frequently over the course of disease nor was its occurrence associated with a specific localisation of metastases.,As heterogeneity with respect to BRAF mutation status is detected in melanoma patients, subsequent testing of initially wild-type patients can yield different results and thus make BRAF inhibitor therapy accessible.,The role of heterogeneity in testing and for clinical response to therapy with a BRAF inhibitor needs to be further investigated.
Adoptive transfer of large numbers of tumor-reactive CD8+ cytotoxic T lymphocytes (CTLs) expanded and differentiated in vitro has shown promising clinical activity against cancer.,However, such protocols are complicated by extensive ex vivo manipulations of tumor-reactive cells and have largely focused on CD8+ CTLs, with much less emphasis on the role and contribution of CD4+ T cells.,Using a mouse model of advanced melanoma, we found that transfer of small numbers of naive tumor-reactive CD4+ T cells into lymphopenic recipients induces substantial T cell expansion, differentiation, and regression of large established tumors without the need for in vitro manipulation.,Surprisingly, CD4+ T cells developed cytotoxic activity, and tumor rejection was dependent on class II-restricted recognition of tumors by tumor-reactive CD4+ T cells.,Furthermore, blockade of the coinhibitory receptor CTL-associated antigen 4 (CTLA-4) on the transferred CD4+ T cells resulted in greater expansion of effector T cells, diminished accumulation of tumor-reactive regulatory T cells, and superior antitumor activity capable of inducing regression of spontaneous mouse melanoma.,These findings suggest a novel potential therapeutic role for cytotoxic CD4+ T cells and CTLA-4 blockade in cancer immunotherapy, and demonstrate the potential advantages of differentiating tumor-reactive CD4+ cells in vivo over current protocols favoring in vitro expansion and differentiation.