CCND1 amplification profiling identifies a subtype of melanoma associated with poor survival and an immunosuppressive tumor microenvironment.

Abstract

e21552 Background: Melanoma is generally regarded as an immunogenic type of tumor that will respond to immune checkpoint therapy. However, melanoma tumors with CCND1 amplification respond poorly to checkpoint therapy. Further understanding of how CCND1 amplification modifies the effect of checkpoint therapy is necessary to design future clinical trials. Methods: We used the data from the Geneplus Institute (n = 302), The Cancer Genome Atlas (TCGA) (n = 367),and the Memorial Sloan Kettering Cancer Center (MSKCC) (n = 350) to identify the incidence of CCND1 amplification and the relationship between CCND1 amplification and survival in melanoma patients and explored molecular mechanisms. Results: The frequency of CCND1 amplification co-occurring with BRAF V600, NRAS, NF1, and KIT mutations was low in these three cohorts. Data from TCGA did not show a statistically significant correlation between CCND1 amplification levels and prognosis of melanoma patients irrespective of immune checkpoint inhibitors (ICIs). In contrast, we found opposite results using the MSKCC cohort where CCND1 amplification was an unfavorable prognostic factor for melanoma patients. This was especially true for patients received ICIs who were harboring a high tumor mutation burden (TMB). The TCGA data showed that CCND1 amplification were related to a higher proportion of immunosuppressive cells (Treg cells and M2 macrophages) and a lower proportion of immunity boosting cells (follicular helper T-cells, naive B-cells, CD8+ T-cells). Furthermore, GSEA analysis from the TCGA database suggests that the signaling pathways such as oxidative phosphorylation, reactive oxygen species, adipogenesis, fatty acid metabolism, DNA repair, and myc targets were differentially enriched in melanoma tumors with CCND1 amplification. Finally, we found that angiogenesis related molecules (HIF1A, VEGFA, VEGFR1, FGF2, FGFR1, FGFR4, HGF, PDGFA, PDGFRA, ANGPT1, and ANGPT2) were remarkable decreased in a CCND1 High Amplification group from the TCGA database. Conclusions: Melanoma with CCND1 amplificationis an independent genomic subtype associated with a poor prognosis, an immunosuppressive TME, activated oxidative and lipid metabolism, and down-regulated angiogenesis. Taken together, avoiding ICIs and antiangiogenic agents, while employing CDK4/6 inhibitors alone or in combination with ICIs, targeting oxidative and lipid metabolism pathway may be effective and promising therapeutic strategies for melanoma patients harboring CCND1 amplification.