RNA-sequencing of cutaneous melanoma and non-small cell lung cancer biopsies

We used a proteogenomic approach combining RNA-sequencing and mass spectrometry to study the MHC I-immunopeptidome of cutaneous melanoma and non-small cell lung cancer (NSCLC) samples. The RNA-sequencing of each sample was used to construct sample-specific databases for the mass spectrometry-based identification of MHC I-associated peptides (MAPs). MAPs were then filtered based on their RNA expression in the respective cancer types from The Cancer Genome Atlas (TCGA-SKCM for melanoma MAPs, or TCGA-LUSC and TCGA-LUAD for NSCLC MAPs) vs. benign tissues (from the Genotype-Tissue Expression (GTEx) Project, medullary thymic epithelial cells, purified blood and bone marrow cells, and normal melanocytes for melanoma or bronchial brushing samples for NSCLC). MAPs were classified as mutated tumor-specific antigens (mTSAs, derived from non-synonymous mutations expressed in the sample of origin), or unmutated tumor antigens: aberrantly expressed tumor-specific antigens (aeTSAs, no/low expression in benign tissues and at least two times higher expression in TCGA), tumor-associated antigens (TAAs, significant expression in benign tissues and at least two times higher expression in TCGA), lineage-associated antigens (LSAs, specific expression to cancer and normal tissue of origin, i.e., lung and bronchial brushing samples for NSCLC or skin and melanocytes for melanoma). The tumor antigens described here represent attractive targets for immunotherapy of melanoma and NSCLC.