We evaluated neoadjuvant ipilimumab in patients with surgically operable regionally advanced melanoma in order to define markers of activity in the blood and tumor as assessed at baseline (before ipilimumab) and early on-treatment.,Patients were treated with ipilimumab (10 mg/kg intravenously every 3 weeks ×2 doses) bracketing surgery.,Tumor and blood biospecimens were obtained at baseline and at surgery.,Flow cytometry and immunohistochemistry for select biomarkers were performed.,Thirty five patients were enrolled; IIIB (3; N2b), IIIC (32; N2c, N3), IV (2).,Worst toxicities included Grade 3 diarrhea/colitis (5; 14%), hepatitis (2; 6%), rash (1; 3%), elevated lipase (3; 9%).,Median follow up was 18 months: among 33 evaluable patients, median progression free survival (PFS) was 11 months, 95% CI (6.2-19.2).,There was a significant decrease in circulating myeloid derived suppressor cells (MDSC).,Greater decrease in circulating monocyte gate MDSC Lin1−/HLA-DR−/CD33+/CD11b+ was associated with improved PFS (p = 0.03).,There was a significant increase in circulating regulatory T cells (Treg; CD4+CD25hi+Foxp3+) that, unexpectedly, was associated with improved PFS (HR = 0.57; p = 0.034).,Baseline evidence of fully activated type I CD4+ and CD8+ antigen-specific T cell immunity against cancer-testis (NY-ESO-1) and melanocytic lineage (MART-1, gp100) antigens was detected and was significantly potentiated after ipilimumab.,In tumor, there was a significant increase in CD8+ T cells after ipilimumab (p = 0.02).,Ipilimumab induced increased tumor infiltration by fully activated (CD69+) CD3+/CD4+ and CD3+/CD8+ T cells with evidence of induction/potentiation of memory T cells (CD45RO+).,The change in Treg observed within the tumor showed an inverse relationship with clinical benefit and greater decrease in tumor MDSC subset Lin1−/HLA-DR−/CD33+/CD11b+ was associated with improved PFS at one year.,Neoadjuvant evaluation revealed a significant immunomodulating role for ipilimumab on Treg, MDSC and effector T cells in the circulation and tumor microenvironment that warrants further pursuit in the quest for optimizing melanoma immunotherapy.
The most common mutation in melanoma, BRAF(V600E), activates the BRAF serine/threonine kinase and causes excessive MAPK pathway activity1,2.,BRAF(V600E)mutations are also present in benign melanocytic nevi3, highlighting the importance of additional genetic alterations in the genesis of malignant tumors.,Such changes include recurrent copy number variations that result in the amplification of oncogenes4,5.,For certain amplifications, the large number of genes in the interval has precluded an understanding of cooperating oncogenic events.,Here, we have used a zebrafish melanoma model to test genes in a recurrently amplified region on chromosome 1 for the ability to cooperate with BRAF(V600E) and accelerate melanoma.,SETDB1, an enzyme that methylates histone H3 on lysine 9 (H3K9), was found to significantly accelerate melanoma formation in the zebrafish.,Chromatin immunoprecipitation coupled with massively parallel DNA sequencing (ChIP-Seq) and gene expression analyses revealed target genes, including Hox genes, that are transcriptionally dysregulated in response to elevated SETDB1.,Our studies establish SETDB1 as an oncogene in melanoma and underscore the role of chromatin factors in regulating tumorigenesis.