Immunologic responses to anti-PD-1 therapy in melanoma patients occur rapidly with pharmacodynamic T cell responses detectable in blood by 3 weeks.,It is unclear, however, whether these early blood-based observations translate to the tumor microenvironment.,We conducted a study of neoadjuvant/adjuvant anti-PD-1 therapy in stage III/IV melanoma.,We hypothesized that immune reinvigoration in the tumor would be detectable at 3 weeks and this response would correlate with disease-free survival.,We identified a rapid and potent anti-tumor response, with 8/27 patients experiencing a complete or major pathological response after a single dose of anti-PD-1, all of whom remain disease-free.,These rapid pathologic and clinical responses were associated with accumulation of exhausted CD8 T cells in the tumor at 3 weeks with reinvigoration in the blood observed as early as 1 week.,Transcriptional analysis demonstrated a pre-treatment immune signature (Neoadjuvant Response Signature) that was associated with clinical benefit.,In contrast, patients with disease recurrence displayed mechanisms of resistance including immune suppression, mutational escape, and/or tumor evolution.,Neoadjuvant anti-PD-1 treatment is effective in high-risk resectable stage III/IV melanoma.,Pathological response and immunological analyses after a single neoadjuvant dose can be used to predict clinical outcome and to dissect underlying mechanisms in checkpoint blockade.
Knowledge of tumor mutation status is becoming increasingly important for the treatment of cancer, as mutation-specific inhibitors are being developed for clinical use that target only sub-populations of patients with particular tumor genotypes.,Melanoma provides a recent example of this paradigm.,We report here development, validation, and implementation of an assay designed to simultaneously detect 43 common somatic point mutations in 6 genes (BRAF, NRAS, KIT, GNAQ, GNA11, and CTNNB1) potentially relevant to existing and emerging targeted therapies specifically in melanoma.,The test utilizes the SNaPshot method (multiplex PCR, multiplex primer extension, and capillary electrophoresis) and can be performed rapidly with high sensitivity (requiring 5-10% mutant allele frequency) and minimal amounts of DNA (10-20 nanograms).,The assay was validated using cell lines, fresh-frozen tissue, and formalin-fixed paraffin embedded tissue.,Clinical characteristics and the impact on clinical trial enrollment were then assessed for the first 150 melanoma patients whose tumors were genotyped in the Vanderbilt molecular diagnostics lab.,Directing this test to a single disease, 90 of 150 (60%) melanomas from sites throughout the body harbored a mutation tested, including 57, 23, 6, 3, and 2 mutations in BRAF, NRAS, GNAQ, KIT, and CTNNB1, respectively.,Among BRAF V600 mutations, 79%, 12%, 5%, and 4% were V600E, V600K, V600R, and V600M, respectively. 23 of 54 (43%) patients with mutation harboring metastatic disease were subsequently enrolled in genotype-driven trials.,We present development of a simple mutational profiling screen for clinically relevant mutations in melanoma.,Adoption of this genetically-informed approach to the treatment of melanoma has already had an impact on clinical trial enrollment and prioritization of therapy for patients with the disease.