Project description:Whole Genome Sequencing of the murine breast cancer cell line 4T1 and of the murine melanoma cell line B16-ova was carried out with the aim of identifying somatic mutations. We also ran deep Mass Spectrometry proteomics analysis on the same cell lines, aiming to determine which somatic mutations carry over to the protein expression level. Further, we tested these cancer specific protein epitopes (putative neoantigens) for immunogenicity using mouse models. Finally, the putative neoantigens that showed good immunogenic potential were used in tumor growth control experiments with mice engrafted with the two tumor cell lines. In these experiments we tested whether cancer vaccines based on individual neoantigen peptides (MHC-I) restricted the growth of the tumor compared to adequate controls. The overall aim of the project is to validate the ability of our multi-omics/bioinformatics pipeline to identify and deliver neoantigens that can be used to suppress tumor growth. File names Sample names P10859_101_S1_L001_R1_001_BHKWV3CCXY 4T1_S1_L001_R1_001_BHKWV3CCXY P10859_101_S1_L001_R2_001_BHKWV3CCXY 4T1_S1_L001_R2_001_BHKWV3CCXY P10859_101_S1_L002_R1_001_BHKWV3CCXY 4T1_S1_L002_R1_001_BHKWV3CCXY P10859_101_S1_L002_R2_001_BHKWV3CCXY 4T1_S1_L002_R2_001_BHKWV3CCXY P10859_102_S2_L003_R1_001_BHKWV3CCXY B16-OVA_S2_L003_R1_001_BHKWV3CCXY P10859_102_S2_L003_R2_001_BHKWV3CCXY B16-OVA_S2_L003_R2_001_BHKWV3CCXY P10859_102_S2_L004_R1_001_BHKWV3CCXY B16-OVA_S2_L004_R1_001_BHKWV3CCXY P10859_102_S2_L004_R2_001_BHKWV3CCXY B16-OVA_S2_L004_R2_001_BHKWV3CCXY
Project description:Mutations in RNA splicing factors are prevalent across cancers and generate recurrently mis-spliced mRNA isoforms. Here we identified a series of bona fide neoantigens translated from highly stereotyped splicing alterations promoted by neomorphic, leukemia-associated somatic mutations in the splicing machinery. We utilized feature-barcoded peptide-MHC dextramers to isolate neoantigen-specific T cell receptors (TCR) from both healthy donors and patients with leukemia. While circulating neoantigen-specific CD8+ T cells were identified in patients with active disease, they were dysfunctional with reduced inflammatory response gene signatures. In contrast, donor CD8+ T cells with tumor-reactive TCRs were present following curative allogeneic hematopoietic cell transplant. T cells engineered with TCRs recognizing an SRSF2 mutant-induced neoantigen in CLK3 resulted in specific recognition and cytotoxicity of SRSF2 mutant leukemia. These data identify RNA mis-splicing derived neoantigens and neoantigen-specific TCRs across patients and provide proof-of-concept to genetically redirect T cells to public mis-splicing derived neoantigens in myeloid leukemias.
Project description:Somatic mutations in cancer are a potential source of cancer specific neoantigens. Acute myeloid leukemia (AML) has common recurrent mutations shared between patients in addition to private mutations specific to individuals. We hypothesized that neoantigens derived from recurrent shared mutations would be attractive targets for future immunotherapy and sought to study the Class I and II HLA ligandomes of thirteen primary AML tumor samples and two AML cell lines (OCI-AML3 and MV4-11) using mass spectrometry. We identified two endogenous, mutation-bearing HLA Class I ligands from NPM1, which are predicted to bind the common HLA haplotypes, HLA-A*03:01 and HLA-A*02:01 respectively. We further derived CD8+ T cells from healthy donor peripheral blood samples which bound mutant-peptide loaded A*03:01 and A*02:01 tetramers, suggesting a new source of NPM1 mutation-specific T cell receptors (TCRs) for future evaluation. Since NPM1 is mutated in approximately one-third of patients with AML, the finding of endogenous NPM1 neoantigens supports future studies evaluating immunotherapeutic approaches against this target, for this subset of patients with AML.
Project description:Cancer somatic mutations can generate neoantigens that distinguish malignant from normal cells. Such neoantigens have been implicated in response to immunotherapies including immune checkpoint blockade, yet their identification and validation remains challenging. Here we discover neoantigens in human mantle cell lymphomas using an integrated strategy for genomic and proteomic tumor antigen discovery that interrogates peptides presented within the tumor major histocompatibility complex (MHC) class I and class II molecules. We applied this approach to systematically identify neoantigen peptides in diagnostic tumor specimens from 17 patients. Remarkably, the 52 discovered neoantigenic peptides were invariably derived from the lymphoma immunoglobulin (Ig) heavy or light chain variable regions. Although we could identify MHC presentation of private germline polymorphic alleles, no mutated peptides were recovered from non-Ig somatically mutated genes. The immunoglobulin variable region somatic mutations were almost exclusively presented by MHC-II. We found T-cells specific for an immunoglobulin-derived neoantigen in the blood of a patient using MHC-II tetramers, and these T-cell clones expanded in frequency following tumor vaccination. These results demonstrate that an integrative approach combining MHC isolation, peptide identification and exome sequencing is an effective platform to uncover tumor neoantigens. Application of this strategy to human lymphoma implicates immunoglobulin neoantigens as targets for lymphoma immunotherapy.
Project description:Cancer somatic mutations can generate neoantigens that distinguish malignant from normal cells. Such neoantigens have been implicated in response to immunotherapies including immune checkpoint blockade, yet their identification and validation remains challenging. Here we discover neoantigens in human mantle cell lymphomas using an integrated strategy for genomic and proteomic tumor antigen discovery that interrogates peptides presented within the tumor major histocompatibility complex (MHC) class I and class II molecules. We applied this approach to systematically identify neoantigen peptides in diagnostic tumor specimens from 17 patients and several cell lines. Remarkably, the discovered neoantigenic peptides were invariably derived from the lymphoma immunoglobulin (Ig) heavy or light chain variable regions. Although we could identify MHC presentation of private germline polymorphic alleles, no mutated peptides were recovered from non-Ig somatically mutated genes. The immunoglobulin variable region somatic mutations were almost exclusively presented by MHC-II. We found T-cells specific for an immunoglobulin-derived neoantigen in the blood of a patient using MHC-II tetramers, and these T-cell clones expanded in frequency following tumor vaccination. These results demonstrate that an integrative approach combining MHC isolation, peptide identification and exome sequencing is an effective platform to uncover tumor neoantigens. Application of this strategy to human lymphoma implicates immunoglobulin neoantigens as targets for lymphoma immunotherapy.
Project description:Somatic L1 retrotransposition events have been shown to occur in epithelial cancers1-8. Here, we attempted to determine how early somatic L1 insertions occurred during the development of gastrointestinal (GI) cancers. Using L1-targeted resequencing (L1-seq), we studied different stages of four colorectal cancers arising from colonic polyps, seven pancreatic carcinomas, as well as seven gastric cancers. Surprisingly, we found somatic L1 insertions not only in all cancer types and metastases, but also in colonic adenomas, well-known cancer precursors. Some insertions were also present in low quantities in normal GI tissues, occasionally caught in the act of being clonally fixed in the adjacent tumors. Insertions in adenomas and cancers numbered in the hundreds and many were present in multiple tumor sections implying clonal distribution. Our results demonstrate that extensive somatic insertional mutagenesis occurs very early during the development of GI tumors, probably before dysplastic growth. Here we show Human SNP 6.0 Array experiments on DNAs from four colorectal cancer patients (1BV, 2BV, 3BV, and 4BV) with polyps and metastases. Here we characterize the samples for CNVs and compare the samples' CNV status to their respective somatic L1 retrotransposition profile.
Project description:Somatic L1 retrotransposition events have been shown to occur in epithelial cancers1-8. Here, we attempted to determine how early somatic L1 insertions occurred during the development of gastrointestinal (GI) cancers. Using L1-targeted resequencing (L1-seq), we studied different stages of four colorectal cancers arising from colonic polyps, seven pancreatic carcinomas, as well as seven gastric cancers. Surprisingly, we found somatic L1 insertions not only in all cancer types and metastases, but also in colonic adenomas, well-known cancer precursors. Some insertions were also present in low quantities in normal GI tissues, occasionally caught in the act of being clonally fixed in the adjacent tumors. Insertions in adenomas and cancers numbered in the hundreds and many were present in multiple tumor sections implying clonal distribution. Our results demonstrate that extensive somatic insertional mutagenesis occurs very early during the development of GI tumors, probably before dysplastic growth.
Project description:Somatic L1 retrotransposition events have been shown to occur in epithelial cancers1-8. Here, we attempted to determine how early somatic L1 insertions occurred during the development of gastrointestinal (GI) cancers. Using L1-targeted resequencing (L1-seq), we studied different stages of four colorectal cancers arising from colonic polyps, seven pancreatic carcinomas, as well as seven gastric cancers. Surprisingly, we found somatic L1 insertions not only in all cancer types and metastases, but also in colonic adenomas, well-known cancer precursors. Some insertions were also present in low quantities in normal GI tissues, occasionally caught in the act of being clonally fixed in the adjacent tumors. Insertions in adenomas and cancers numbered in the hundreds and many were present in multiple tumor sections implying clonal distribution. Our results demonstrate that extensive somatic insertional mutagenesis occurs very early during the development of GI tumors, probably before dysplastic growth. We assessed the impact of somatic L1 insertions on the expression of the corresponding protein-coding genes by comparing protein abundance in the polyp with the highest number of somatic L1 insertions with that of its paired normal colon using mass spectrometry analysis. Of the 10 validated somatic insertions that were in protein coding regions in the polyp, two proteins – KIAA1217 and WARS2 – were downregulated in the adenoma >90% and >70%, respectively.