A T-cell antigen atlas for meningioma: novel options for immunotherapy

Meningiomas are the most common primary intracranial tumors. Although most symptomatic cases can be managed by surgery and/or radiotherapy, a relevant number of patients experience an unfavorable clinical course and additional treatment options are needed. As meningiomas are often perfused by dural branches of the external carotid artery, which is located outside the blood-brain barrier, they might be an accessible target for immunotherapy. However, the landscape of naturally presented tumor antigens in meningioma is unknown. We here provide a T-cell antigen atlas for meningioma by in-depth profiling of the naturally presented immunopeptidome using LC-MS/MS. Candidate target antigens were selected based on a comparative approach using an extensive immunopeptidome data set of normal tissues. Meningioma-exclusive antigens for HLA class I and II are described here for the first time. Top-ranking targets were further functionally characterized by showing their immunogenicity through in vitro T-cell priming assays. Thus, we provide an atlas of meningioma T-cell antigens which will be publicly available for further research. In addition, we have identified novel actionable targets that warrant further investigation as an immunotherapy option for meningioma

Charakterisierung von T-Zell-Epitopen für Antigen-spezifische Immuntherapie-Ansätze gegen myeloproliferative Neoplasien und das Multiple Myelom

Dissertation ist gesperrt bis 23. Oktober 2022 !In den vergangenen Jahren hat die Tumor-Immuntherapie zunehmend an Bedeutung gewonnen. Insbesondere Antigen-spezifische Therapien sind ein vielversprechender Ansatz für eine gezielte Bekämpfung von Krebszellen. Zahlreiche Studien zeigen, dass die Aktivierung des Immunsystems zur Reduktion der Tumorlast, Langzeitkontrolle oder Heilung von Tumorerkrankungen beitragen kann. Insbesondere T-Zell-basierte Strategien können hierzu einen wertvollen Beitrag leisten. Die Grundvoraussetzung hierfür ist die Auswahl geeigneter Antigene, die eine gezielte anti-Tumor T-Zell-Antwort ermöglichen. Diese Antigene sind Tumor-assoziierte Peptide, die idealerweise hochfrequent und exklusiv über humanes Leukozytenantigen (HLA) von malignen Zellen präsentiert werden. Zur Identifizierung solcher Antigene hat unsere Gruppe einen Massenspektrometrie-basierten Ansatz mit anschließender immunologischer Charakterisierung entwickelt. Diese Dissertation befasst sich vorrangig mit der Charakterisierung der identifizierten, HLA-präsentierten Peptide zur Entwicklung Antigen-spezifischer Immuntherapie-Konzepte gegen myeloproliferative Neoplasien (MPNs) und das Multiple Myelom (MM). KAPITEL 1 beschreibt die umfangreiche Analyse der natürlich präsentierten HLA-Liganden in Primärproben der chronischen myeloischen Leukämie (CML). Gegen die identifizierten, hochfrequent präsentierten, CML-assoziierten Antigene konnten wir spontane Gedächtnis-T-Zell-Antworten sowie de novo induzierte, multifunktionale und zytotoxische T-Zellen in Proben von CML Patienten nachweisen. Diese Antigene konnten somit als geeignete Ziel- strukturen für T-Zell-basierte Immuntherapien bestätigt werden. In KAPITEL 2 identifizierten wir in Primärproben BCR-ABL-negativer MPN-Patienten hochfrequente MPN-assoziierte Peptide. Der Vergleich von MPN- mit akute myeloische Leukämie (AML)-exklusiven Antigenen zeigte einen beachtlichen Anteil gemeinsamer Proteine. Hierauf basierend konnten wir multifunktionale Gedächtnis-T-Zellen gegen AML-assoziierte T-Zell-Epitope in vitro in MPN Patienten detektieren. KAPITEL 3 beschreibt natürlich präsentierte Peptide aus intrazellulären Domänen bekannter Tumor-assozierter Oberflächenantigene als mögliche Zielstrukturen für Immuntherapien. Hierzu identifizierten wir in Proben von MM Patienten den HLA-B*18 Liganden P(BCMA)B*18 aus dem B-Zell-Reifungsantigen. Die Immunogenität von P(BCMA)B*18 konnte durch spontane T-Zell-Antworten in MM Patientenproben bestätigt werden. Des Weiteren induzierte P(BCMA)B*18 in Kombination mit Immuncheckpoint-Inhibitoren in vitro multifunktionale, zytotoxische T-Zellen in MM Proben. P(BCMA)B*18 ist daher ein vielversprechendes Zielantigen für Immuntherapien von B-Zell-Erkrankungen. Zusammenfassend beschreiben wir neue, immunogene Zielstrukturen für T-Zell-basierte Immuntherapien zur gezielten Bekämpfung hämatologischer Neoplasien und deren Vorstufen.In the past years, cancer-immunotherapy has gained more and more momentum. To this end, several studies provide evidence that immunological control can contribute to remission, long-term control, or even cure of malignant disease. Apart from unspecific strategies including immune checkpoint inhibitors, advanced antigen-specific approaches hold the promise to target cancer cells more specifically. Particularly T-cell-based strategies are on the advance to restore immune responses and thereby improve the outcome in patients. The prerequisite for such approaches is the selection of feasible targets for anti-cancer T-cell responses. Ideally, such targets are tumor-associated peptides that are frequently and exclusively presented by human leukocyte antigen (HLA) on malignant cells. To identify such antigens, our group implemented a mass spectrometry-based approach with subsequent immunological characterization of the identified peptides. This thesis aims at the further characterization of the identified T-cell epitopes for the development of antigen-specific immunotherapy concepts to target myeloproliferative neoplasms (MPNs) and multiple myeloma (MM). CHAPTER 1 illustrates the comprehensive mapping of the naturally presented immunopeptidome landscape in chronic myeloid leukemia (CML). We detected spontaneous preexisting T-cell responses against novel, frequently presented, highly immunogenic, CML-associated peptides and induced multifunctional and cytotoxic antigen-specific T cells de novo in CML samples. Thus, we validated these antigens as prime targets for T-cell-based immunotherapy. In CHAPTER 2 we identified novel frequently presented MPN-associated peptides in primary samples of BCR-ABL-negative MPN patients. Alignment of MPN- and acute myeloid leukemia (AML)-exclusive antigens revealed a significant proportion of shared proteins. In consequence, we detected in vitro multifunctional memory T cells specific for AML-associated T-cell epitopes in MPN patients. CHAPTER 3 provides a proof-of-concept study for the natural HLA-dependent presentation of peptides derived from intracellular domains of established tumor-associated surface antigens as potential targets for immunotherapy. We identified the HLA-B*18 ligand P(BCMA)B*18 derived from the B-cell maturation antigen on primary MM and chronic lymphocytic leukemia (CLL) samples. P(BCMA)B*18 is highly immunogenic as demonstrated by spontaneous BCMA-specific T-cell responses in MM samples. Combination of P(BCMA)B*18 with in vitro immune checkpoint inhibition in MM samples induced multifunctional cytotoxic T cells de novo. P(BCMA)B*18 is thus a promising target for immunotherapy and immunomonitoring in B-cell malignancies. Taken together, we provide a novel category of highly immunogenic antigens for tailored off-the-shelf T-cell-based and combinatorial immunotherapy approaches to target hematological malignancies and to circumvent leukemic transformation and progression of disease

Antigen Targets for the Development of Immunotherapies in Leukemia

Immunotherapeutic approaches, including allogeneic stem cell transplantation and donor lymphocyte infusion, have significantly improved the prognosis of leukemia patients. Further efforts are now focusing on the development of immunotherapies that are able to target leukemic cells more specifically, comprising monoclonal antibodies, chimeric antigen receptor (CAR) T cells, and dendritic cell- or peptide-based vaccination strategies. One main prerequisite for such antigen-specific approaches is the selection of suitable target structures on leukemic cells. In general, the targets for anti-cancer immunotherapies can be divided into two groups: (1) T-cell epitopes relying on the presentation of peptides via human leukocyte antigen (HLA) molecules and (2) surface structures, which are HLA-independently expressed on cancer cells. This review discusses the most promising tumor antigens as well as the underlying discovery and selection strategies for the development of anti-leukemia immunotherapies

Prevalence of COVID-19-associated symptoms during acute infection in relation to SARS-CoV-2-directed humoral and cellular immune responses in a mild-diseased convalescent cohort ?

OBJECTIVE: Besides SARS-CoV-2-directed humoral immune responses, T cell responses are indispensable for effective anti-viral immunity. Recent data have shown a correlation of COVID-19 symptoms with humoral immune response, but so far little is known on the association of SARS-CoV-2-directed T cell responses and disease severity. We here evaluated the prevalence of different clinical COVID-19 symptoms in relation to SARS-CoV-2-directed humoral and cellular immune responses. METHODS: Severity of eight different symptoms during acute infection were assessed questionnaire-based from 193 convalescent individuals and evaluated in relation to SARS-CoV-2 antibody levels and intensity of SARS-CoV-2-specific T cell responses 2 - 8 weeks after positive PCR. RESULTS: Whereas increased IgG serum levels could be associated with severity of most symptoms, no difference in T cell response intensity between different symptom severities was observed for the majority of COVID-19 symptoms. However, when analyzing loss of smell or taste and cough, awareness of more severe symptoms was associated with reduced T cell response intensities. CONCLUSION: These data suggest that rapid virus clearance mediated by SARS-CoV-2-specific T cells prevents severe symptoms of COVID-19