Project description:Lynch syndrome (LS) patients develop DNA mismatch repair deficient tumors which generate high loads of neoantigens (neoAgs), thus constituting a well-defined population that can benefit from cancer immune-interception strategies, including neoantigen-based vaccines. Using paired whole-exome sequencing and mRNAseq of colorectal cancers (CRC) (n=13) and pre-cancers (n=61) from our LS patient cohort (N=46), we performed in-silico prediction and immunogenicity ranking of highly recurrent frameshift-neoags, followed by their in-vitro validation. We described the somatic mutation landscape in all cancers and pre-cancers, and showed that mutation burden is positively correlated with neoAgs load. Furthermore, our in-vitro validation showed a 65% validation rate of our top 100 predicted neoags. Consistent with neoAgs burden, our transcriptomic results revealed increased infiltration of CD8+ and CD4+ T-cells in microsatellite unstable samples. Overall, our neoAgs catalog and all other findings, improve our understanding of cancer development in LS and guide us towards the advancement of immunoprevention vaccine strategies.
Project description:Despite aggressive multi-modal treatment, advanced head and neck squamous cell carcinoma (HNSCC) patients are at high risk of recurrence. Matched pairs (n=38) of primary/recurrent tumors were subjected to whole exome and RNA sequencing. Mutational landscapes and genomic copy number alterations indicated diverging clonal origins in a subset of cases. Transcriptional subtyping (classical/CL, basal/BA, inflamed-mesenchymal/IMS) in primary and recurrent HNSCC (n=112) revealed more frequent CL and IMS in primary tumors with low recurrence rates and a prevalence of BA in recurrent tumors associated with p-EMT and early recurrence. 44% of matched cases underwent a subtype change from primary to recurrent tumors, preferably from IMS to BA or CL. In recurrences, HYPOXIA, P-EMT and RADIATION RESISTANCE signatures were up- and TUMOR INFLAMMATION down-regulated compared to index tumors. A therapy-induced selection of transcriptional subtypes demonstrates the importance of molecular characterization of recurrences for second-line therapy decisions to enable optimally tailored treatments.
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:Vaccination of patients against neoantigens expressed in concurrent tumors, recurrent tumors, or tumors developing in individuals at risk of cancer is posing major challenges in terms of which antigens to target and is limited to patients expressing neoantigens in their tumors. Here, we describe a vaccination strategy against antigens that were induced in tumor cells by downregulation of the peptide transporter associated with antigen processing (TAP). Vaccination against TAP downregulation-induced antigens was more effective than vaccination against mutation-derived neoantigens, was devoid of measurable toxicity, and inhibited the growth of concurrent and future tumors in models of recurrence and premalignant disease. Human CD8+ T cells stimulated with TAPlow dendritic cells elicited a polyclonal T-cell response that recognized tumor cells with experimentally reduced TAP expression. Vaccination against TAP downregulation-induced antigens overcomes the main limitations of vaccinating against mostly unique tumor-resident neoantigens and could represent a simpler vaccination strategy that will be applicable to most patients with cancer.
Project description:Neoantigen discovery in pediatric brain tumors is hampered by their low mutational burden and scant tissue availability. We developed a low-input proteogenomic approach combining tumor DNA/RNA sequencing and mass spectrometry proteomics to identify tumor-restricted (neoantigen) peptides arising from multiple genomic aberrations to generate a highly target-specific, autologous, personalized T cell immunotherapy. Our data indicate that novel splice junctions are the primary source of neoantigens in medulloblastoma, a common pediatric brain tumor. Proteogenomically identified tumor-specific peptides are immunogenic and generate MHC II-based T cell responses. Moreover, polyclonal and polyfunctional T cells specific for tumor-specific peptides effectively eliminated tumor cells in vitro. Targeting novel tumor-specific antigens obviates the issue of central immune tolerance while potentially providing a safety margin favoring combination with other immune-activating therapies. These findings demonstrate the proteogenomic discovery of immunogenic tumor-specific peptides and lay the groundwork for personalized targeted T cell therapies for children with brain tumors.
Project description:Immunotherapies targeting cancer-specific immunogenic neoantigens have revolutionized the treatment of cancer patients. Recent evidence suggests that epigenetic therapies could synergize with immunotherapies, mediating the de-repression of endogenous retroviral element (ERV)-encoded promoters, and the initiation of transcription. Here we use RNA sequencing from cancer cells treated with DNMT and/or HDAC inhibitors, to assemble a de novo transcriptome and identified 3,023 ERV-derived, treatment-induced novel polA+ transcripts (TINPATs), encoding for 61,426 novel open reading frames. We further demonstrate, using human leukocyte antigen immunopeptidomics, the existence of treatment-induced neoepitopes (t-neoepitopes) derived from TINPATs. We demonstrated the potential of the identified t-neoepitopes to elicit an immunogenic T-cell response and cancer cell killing. The presence of t-neoepitopes was further verified in AML patient samples 48 h and /96 h after in vivo treatment with the DNMT inhibitor Decitabine. Our findings highlight a novel mechanism of ERV-derived neoantigens in epigenetic and immune therapies.
Project description:Immunotherapies targeting cancer-specific neoantigens have revolutionized the treatment of cancer patients. Recent evidence suggests that epigenetic therapies synergize with immunotherapies, mediated bythe de-repression of endogenous retroviral element (ERV)-encoded promoters, and the initiation of transcription. Here, we use deep RNA sequencing from cancer cell lines treated with DNA methyltransferase inhibitors (DNMTi) and/or Histone deacetylase transferase inhibitors (HDACi), to assemble a de novo transcriptome and identified 3,023 ERV-derived, treatment-induced novel polyadenylated transcripts (TINPATs), encoding for 61,426 open reading frames. Using Immunopeptidomics, we further demonstrate the human leukocyte antigen (HLA) presentation of treatment-induced neoepitopes (t-neoepitopes) derived from TINPATs. We illustrate the potential of the identified t-neoepitopes to elicit a T-cell response and cancer cell killing. The presence of t-neoepitopes was further verified in AML patient samples 48/96 h after in vivo treatment with the DNMT inhibitor Decitabine. Our findings highlight a novel mechanism of ERV-derived neoantigens in epigenetic and immune therapies.
Project description:Targeting tumor-specific neoantigens is promising for cancer immunotherapy, yet their ultra-low expression on tumor cells poses significant challenges for T cell therapies. Here, we found that chimeric antigen receptors (CARs) exhibited 10-100 times lower sensitivity compared to T cell receptors (TCRs) when targeting p53R175H common neoantigen. To enhance CAR functionality, we introduce T cell receptor fusion construct (TRuC) and synthetic TCR and antigen receptor (STAR). Our data demonstrate that STAR, which incorporates TCR-mimic antibody fragments and complete TCR signaling machinery, optimally reproduces antigen sensitivity of TCRs. STAR outperforms both CAR and TRuC in redirecting both CD8+ and CD4+ T cells to recognize HLA class I neoantigens. In vitro, human primary T cells engineered with STAR kill multiple cancer cell lines with low neoantigen density better than CAR-T and TRuC-T cells. In tumor mouse models, STAR-T cells outperform CAR-T and TRuC-T cells in controlling neoantigen-low breast cancer and leukemia. Taken together, our findings highlight severe defects in CAR sensitivity and introduce STAR as a more sensitive synthetic receptor, providing a new framework for T cell-based immunotherapy targeting tumors with low neoantigen density.