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  • American Association for Cancer Research (AACR)  (5)
  • 1
    In: Clinical Cancer Research, American Association for Cancer Research (AACR), Vol. 28, No. 24 ( 2022-12-15), p. 5368-5382
    Abstract: The low mutational load of some cancers is considered one reason for the difficulty to develop effective tumor vaccines. To overcome this problem, we developed a strategy to design neopeptides through single amino acid mutations to enhance their immunogenicity. Experimental Design: Exome and RNA sequencing as well as in silico HLA-binding predictions to autologous HLA molecules were used to identify candidate neopeptides. Subsequently, in silico HLA-anchor placements were used to deduce putative T-cell receptor (TCR) contacts of peptides. Single amino acids of TCR contacting residues were then mutated by amino acid replacements. Overall, 175 peptides were synthesized and sets of 25 each containing both peptides designed to bind to HLA class I and II molecules applied in the vaccination. Upon development of a tumor recurrence, the tumor-infiltrating lymphocytes (TIL) were characterized in detail both at the bulk and clonal level. Results: The immune response of peripheral blood T cells to vaccine peptides, including natural peptides and designed neopeptides, gradually increased with repetitive vaccination, but remained low. In contrast, at the time of tumor recurrence, CD8+ TILs and CD4+ TILs responded to 45% and 100%, respectively, of the vaccine peptides. Furthermore, TIL-derived CD4+ T-cell clones showed strong responses and tumor cell lysis not only against the designed neopeptide but also against the unmutated natural peptides of the tumor. Conclusions: Turning tumor self-peptides into foreign antigens by introduction of designed mutations is a promising strategy to induce strong intratumoral CD4+ T-cell responses in a cold tumor like glioblastoma.
    Type of Medium: Online Resource
    ISSN: 1078-0432 , 1557-3265
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2022
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  • 2
    In: Clinical Cancer Research, American Association for Cancer Research (AACR), Vol. 10, No. 6 ( 2004-03-15), p. 1871-1874
    Abstract: Purpose: In the setting of a prospective clinical trial, we determined the predictive value of the methylation status of the O-6-methylguanine-DNA methyltransferase (MGMT) promoter for outcome in glioblastoma patients treated with the alkylating agent temozolomide. Expression of this excision repair enzyme has been associated with resistance to alkylating chemotherapy. Experimental Design: The methylation status of MGMT in the tumor biopsies was evaluated in 38 patients undergoing resection for newly diagnosed glioblastoma and enrolled in a Phase II trial testing concomitant and adjuvant temozolomide and radiation. The epigenetic silencing of the MGMT gene was determined using methylation-specific PCR. Results: Inactivation of the MGMT gene by promoter methylation was associated with longer survival (P = 0.0051; Log-rank test). At 18 months, survival was 62% (16 of 26) for patients testing positive for a methylated MGMT promoter but reached only 8% (1 of 12) in absence of methylation (P = 0.002; Fisher’s exact test). In the presence of other clinically relevant factors, methylation of the MGMT promoter remains the only significant predictor (P = 0.017; Cox regression). Conclusions: This prospective clinical trial identifies MGMT-methylation status as an independent predictor for glioblastoma patients treated with a methylating agent. The association of the epigenetic inactivation of the DNA repair gene MGMT with better outcome in this homogenous cohort may have important implications for the design of future trials and supports efforts to deplete MGMT by O-6-benzylguanine, a noncytotoxic substrate of this enzyme.
    Type of Medium: Online Resource
    ISSN: 1078-0432 , 1557-3265
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2004
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    detail.hit.zdb_id: 2036787-9
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  • 3
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 82, No. 12_Supplement ( 2022-06-15), p. 1991-1991
    Abstract: Glioblastoma is known as the most aggressive and most common malignant primary tumor in the central nervous system. Current treatment options comprise maximal surgical resection followed by radiation and/or chemotherapy with temozolomide. However, these therapies are not able to eliminate all tumor cells, which in turn inevitably leads to disease recurrence and an alteration of identified targets in the context of clonal evolution and potential hypermutation. T cell-based immunotherapy holds great promise to target malignant cells with CAR T cell and vaccination strategies, showing first promising results in glioblastoma. These therapies rely on the rejection of cancer cells through recognition of tumor antigens and T cell-mediated cytotoxicity. In previous work, we have characterized such tumor antigens in primary glioblastoma (Neidert et al., Acta Neuropathol, 2018), nonetheless, alterations in relapsed disease have not been addressed thus far. This study investigated the whole exome, transcriptome, and mass-spectrometry-based immunopeptidome of 38 primary and 24 recurrent tumors, including 22 autologous glioblastoma pairs, to determine alterations that occur during glioblastoma progression on multiple comics levels. In concordance with Neftel et al., Cell, 2019, we identified mutations that can be allocated to astrocyte- and mesenchymal-like classified genes. In addition, an increase in the mutation rate in recurrent glioblastoma was observed which is attributed to radiation and chemotherapy pretreatment of tumors. These newly arising tumor-specific mutations give rise to HLA-presented neoepitopes in the primary cohort. Moreover, we identified transcripts that are differentially expressed between the two cohorts, showing a higher expression of transcripts related to immune system responses in the recurrent cohort. Immunopeptidome analysis of the two cohorts revealed high frequent glioblastoma-exclusive HLA class I and class II ligands presented in both the primary and recurrent cohort, serving as universally applicable tumor antigens. Class I and II HLA ligands of each sample were analyzed and revealed 2,146 HLA class I- and 2,753 HLA class II presented antigens that were uniquely identified on primary glioblastoma. A total of 610 and 1,886 source proteins represent recurrence-exclusive antigens presented on HLA class I or II molecules, respectively. Together this work addressed differences in tumor antigen expression and presentation between primary and recurrent glioblastoma using these omics layers to create an overview of the alterations that occur during disease progression. Besides providing a deep insight into the glioblastoma (immuno-)biology during progression, this study yields targets for innovative immunotherapeutic approaches to eliminate residual cells and improve survival in glioblastoma patients. Citation Format: Marissa L. Dubbelaar, Lena K. Freudenmann, Jonas Scheid, Julia Velz, Gioele Medici, Konstantina Kapolou, Malte Mohme, Leon Bichmann, Marie Gauder, Stefan Czemmel, Christopher Mohr, Daniel J. Kowalewski, Manfred Westphal, Katrin Lamszus, Luca Regli, Michael Weller, Hans-Georg Rammensee, Helmut Salih, Marian C. Neidert, Juliane S. Walz. Characterization of the exome, transcriptome, and immunopeptidome to map alterations in primary and recurrent glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1991.
    Type of Medium: Online Resource
    ISSN: 1538-7445
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2022
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  • 4
    In: Clinical Cancer Research, American Association for Cancer Research (AACR), Vol. 28, No. 21 ( 2022-11-01), p. 4747-4756
    Abstract: Most chimeric antigen receptor (CAR) T-cell strategies against glioblastoma have demonstrated only modest therapeutic activity and are based on persistent gene modification strategies that have limited transgene capacity, long manufacturing processes, and the risk for uncontrollable off-tumor toxicities. mRNA-based T-cell modifications are an emerging safe, rapid, and cost-effective alternative to overcome these challenges, but are underexplored against glioblastoma. Experimental Design: We generated mouse and human mRNA-based multifunctional T cells coexpressing a multitargeting CAR based on the natural killer group 2D (NKG2D) receptor and the proinflammatory cytokines IL12 and IFNα2 and assessed their antiglioma activity in vitro and in vivo. Results: Compared with T cells that either expressed the CAR or cytokines alone, multifunctional CAR T cells demonstrated increased antiglioma activity in vitro and in vivo in three orthotopic immunocompetent mouse glioma models without signs of toxicity. Mechanistically, the coexpression of IL12 and IFNα2 in addition to the CAR promoted a proinflammatory tumor microenvironment and reduced T-cell exhaustion as demonstrated by ex vivo immune phenotyping, cytokine profiling, and RNA sequencing. The translational potential was demonstrated by image-based single-cell analyses of mRNA-modified T cells in patient glioblastoma samples with a complex cellular microenvironment. This revealed strong antiglioma activity of human mRNA-based multifunctional NKG2D CAR T cells coexpressing IL12 and IFNα2 whereas T cells that expressed either the CAR or cytokines alone did not demonstrate comparable antiglioma activity. Conclusions: These data provide a robust rationale for future clinical studies with mRNA-based multifunctional CAR T cells to treat malignant brain tumors.
    Type of Medium: Online Resource
    ISSN: 1078-0432 , 1557-3265
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2022
    detail.hit.zdb_id: 1225457-5
    detail.hit.zdb_id: 2036787-9
    Location Call Number Limitation Availability
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  • 5
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 82, No. 12_Supplement ( 2022-06-15), p. 1375-1375
    Abstract: Glioblastoma is the most common primary malignant neoplasm of the central nervous system in adults. Current treatment options comprise maximal surgical resection followed by radiation and/or chemotherapy with temozolomide. However, these procedures are unable to eliminate all tumor cells, which in turn lead to disease recurrence accounting for the poor prognosis. Glioblastoma is a highly infiltrative tumor in which recurrence originates from the unresectable peritumoral infiltration zone. Thus, novel treatment options specifically targeting the tumor cells in the infiltration zone are needed to prevent relapse and enable long-lasting remission. In this work, we performed multi-omics spatial analysis of the necrotic center (NEC), the gadolinium contrast-enhanced region (T1), and the infiltration zone (INF) to assess immunological relevant aspects of tumor heterogeneity. By integrating mass spectrometry-based immunopeptidome analysis with next generation sequencing methods (whole exome and RNA sequencing, DNA methylation), we aimed to identify the intra-tumoral regional heterogeneity of T cell antigens with a special focus on the peritumoral infiltration zone. For multi-omics analysis, HLA peptides and genetic material from 15 glioblastoma patients were extracted and analyzed from the three zones NEC, T1, INF and for four patients additionally from adjacent benign (BEN) brain tissue. A total of 24,699 unique HLA class I and 17,394 HLA class II peptides were identified. Comparative profiling of peptides from our study and a benign tissue database (in-house (n=429) combined with HLA ligand atlas (https://hla-ligand-atlas.org)) revealed that 6% (970/15,579), 5% (829/16,442) and 5% (725/13,891) of HLA class I peptides were exclusively presented in the INF, T1 and NEC zone, respectively. 6% (394/7,150), 7% (589/8,736) and 13% (1,725/12,908) of HLA class II peptides showed exclusive representation in the INF, T1 and NEC zone, respectively. Importantly, due to the spatial analysis of the immunopeptidome, we revealed 970 HLA class I and 394 HLA class II peptides exclusively presented in the INF zone. Interestingly, one INF-associated HLA class I peptide, which showed frequent presentation in 36% of glioblastoma immunopeptidomes, is derived from the brain and acute leukemia cytoplasmic protein (BAALC), a highly expressed cell cycle inducer (via MEK kinase-1) in several cancers, including glioblastoma. Integrated RNA/DNA sequencing enabled a greater understanding of spatial tumor antigen presentation and lead to the identification of INF-specific neoepitopes derived from tumor-specific mutations. In summary, we identified the intra-tumoral regional heterogeneity of tumor antigens, which could be used in the future for specific immunotherapy approaches targeting the infiltration zone of glioblastoma. Citation Format: Marcel Wacker, Gioele Medici, Marissa Dubbelaar, Jens Bauer, Annika Nelde, Luca Regli, Michael Weller, Helmut R. Salih, Hans-Georg Rammensee, Marian C. Neidert, Juliane S. Walz. The intra-tumoral spatial heterogeneity of T-cell antigens in glioblastoma: An integrated multi-omics approach [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1375.
    Type of Medium: Online Resource
    ISSN: 1538-7445
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2022
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    detail.hit.zdb_id: 410466-3
    Location Call Number Limitation Availability
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