Project description:Direct analysis of HLA-presented antigens by mass spectrometry provides a comprehensive view on the antigenic landscape of different tissues/malignancies and enables the identification of novel, pathophysiologically relevant T-cell epitopes. Here, we present a systematic and comparative study of the HLA class I and II presented, nonmutant antigenome of multiple myeloma (MM). Quantification of HLA surface expression revealed elevated HLA molecule counts on malignant plasma cells compared with normal B cells, excluding relevant HLA downregulation in MM. Analyzing the presentation of established myeloma-associated T-cell antigens on the HLA ligandome level, we found a substantial proportion of antigens to be only infrequently presented on primary myelomas or to display suboptimal degrees of myeloma specificity. However, unsupervised analysis of our extensive HLA ligand data set delineated a panel of 58 highly specific myeloma-associated antigens (including multiple myeloma SET domain containing protein) which are characterized by frequent and exclusive presentation on myeloma samples. Functional characterization of these target antigens revealed peptide-specific, preexisting CD8+ T-cell responses exclusively in myeloma patients, which is indicative of pathophysiological relevance. Furthermore, in vitro priming experiments revealed that peptide-specific T-cell responses can be induced in response-naive myeloma patients. Together, our results serve to guide antigen selection for T-cell–based immunotherapy of MM.
Project description:The accessibility of cell surface proteins makes them tractable for cancer immunotherapy, but identifying suitable targets remains challenging, and resistance to treatment is common. Technical difficulties precluding the use of whole cell proteomic approaches to characterize cell surface proteins include low abundance, hydrophobicity, and a lack of protease cleavage sites. Furthermore, neither whole-cell proteomic nor transcriptomic data can accurately quantify protein expression at the plasma membrane. Resistance to immunotherapies is commonly mediated by downregulation of the target protein, a particular problem when immunotherapies fail to inhibit a specific biological pathway. Here we have used plasma membrane profiling of primary human myeloma cells to identify an unprecedented number of cell surface proteins and quantify for the first time the entire cell surface proteome of a primary cancer. This approach revealed a novel therapeutic target, SEMA4A, which we potently and selectively targeted with an antibody-drug conjugate in vitro and in vivo. Reduction of SEMA4A expression resulted in marked impairment of myeloma cell growth in vitro, indicating that myeloma cells cannot downregulate SEMA4A to avoid detection. Our data therefore reveal not only a novel myeloma target but provide an exemplar of a top-down approach from the unbiased characterization of a cancer cell surface proteome to novel immunotherapeutic target.
Project description:Analysis of gene expression data to evaluate candidate targets for immunotherapy. Analysis of gene expression data to evaluate candidate targets for immunotherapy, We analyse 7 lung cancer samples and 3 reference samples (2x kidney, 1x lung).
Project description:Clear cell renal cell carcinoma (ccRCC) is the dominant subtype of renal cancer. With currently available therapies, cure of advanced and metastatic ccRCC is achieved only in rare cases. Here, we developed a workflow integrating different -omics technologies to identify ccRCC-specific HLA-presented peptides as potential drug targets for ccRCC immunotherapy. We analyzed frequent ccRCC-specific peptides by MS-based HLA ligandomics of 55 ccRCC tumors (cohort 1), paired non-tumor renal tissues and 158 benign tissues from other organs. Pathways enriched in ccRCC compared to its cell type of origin were identified by transcriptome and gene set enrichment analyses in 51 tumor tissues of the same cohort. To retrieve a list of candidate target genes with involvement in ccRCC pathogenesis, ccRCC-specific pathway genes were intersected with the source genes of tumor-exclusive peptides. The candidates were validated in an independent cohort from the Cancer Genome Atlas (TCGA KIRC, n=452), yielding 113 candidate genes. DNA methylation (TCGA KIRC, n=273), and somatic mutations (TCGA KIRC, n=392), as well as correlations with tumor metabolites (cohort 1, n=30) and immune-oncological markers (cohort 1, n=37) were analyzed to refine regulatory and functional involvements of candidates. Immunogenicity analysis identified candidate epitopes able to activate native CD8+ T cells. Functional analysis of EGLN3, a candidate with frequent ccRCC-specific immunogenic peptides, revealed possible tumor-promoting functions. Integration of HLA ligandomics, transcriptomics, genetic and epigenetic data leads to the identification of novel functionally relevant therapeutic targets for ccRCC immunotherapy. Validation of the identified targets is now mandatory to expand the treatment landscape of ccRCC.
Project description:While there is extensive evidence for genetic variation as a basis for treatment resistance, other sources of variation result from cellular plasticity. Using multiple myeloma as an example of an incurable lymphoid malignancy, we show how cancer cells modulate lineage restriction, adapt their enhancer usage and employ cell-intrinsic diversity for survival and treatment escape. By using single cell transcriptome and chromatin accessibility profiling, we show that distinct transcriptional states co-exist in individual cancer cells and that differential transcriptional regulon usage and enhancer rewiring underlie these alternate transcriptional states. We demonstrate that exposure to standard treatment further promotes transcriptional reprogramming and differential enhancer recruitment, while simultaneously reducing developmental potential. Importantly, treatment generates a novel complement of actionable immunotherapy targets, such as CXCR4, which can be exploited to overcome treatment resistance. Our studies therefore delineate how to transform the cellular plasticity that underlies drug resistance into novel immuno-oncologic therapeutic opportunities.
Project description:A number of reports have demonstrated that tumor-intrinsic mechanisms of resistance, such as the loss of genes critical for antigen presentation and inflammatory responses, along with the activation of various cellular signaling cascades, can limit the efficacy of immunotherapy. Strategies to sensitize tumor cells to immunotherapy may overcome some resistance mechanisms, but identifying therapeutic targets has remained challenging. Here, we integrate a two-cell type (2CT) whole-genome CRISPR-Cas9 screen with dynamic transcriptional profiling of the tumor/T cell interaction to comprehensively identify tumor genes that are induced to promote tumor survival. We assessed the therapeutic potential of pharmacological inhibition of these and other top CRISPR identified targets as combinatorial targets to improve the efficacy of tumor destruction by T cells.