O64: GENOMIC PROFILING USING CIRCULATING NUCLEIC ACIDS IN STAGE IV MELANOMA PATIENTS RECEIVING IMMUNOTHERAPY REVEALS A NOVEL GENE AMPLIFICATION LANDSCAPE AND ALLOWS FOR DETECTION OF ACTIONABLE GENE MUTATIONS

Abstract Introduction Serial monitoring for disease progression and therapeutic efficacy at the molecular level in metastatic melanoma is hampered by a lack of reliable blood borne biomarkers. Molecular profiling tumours almost impractical due to risks procedure related morbidity sampling inefficiency representing tumour heterogeneity. Cell free DNA allows changes over course immunotherapy. We investigated utility somatic mutation gene amplification analyses patients receiving Method was extracted from plasma using QIAamp Circulating Nucleic Acid Kit (Qiagen). Pathway focused status performed ARMs PCR QBiomarker Somatic Mutation Arrays Gene analysis Real Time Quantitative (Roche) RT2 Profiler Result A total twenty with stage IV immunotherapy were enrolled this study. The BRAF p.V600E detected cfDNA 80% positive patients. also profiled 84 genes cancer inflammation immunity pathway. There significant difference copy numbers several (CTLA-4, CXCL12, CXCL5, IDO1, TGFB, IFNG, IL4, PTGS2, AICDA, HLA-A, CCL4, ACKR3, TP53, MYC) between progressive response (n=20, p < 0.05). Conclusion postulate that cell pathway may be useful evaluating response. Take-home message Genomic circulating nucleic acids melanoma.