HLA ligandome analysis of Multiple Myeloma - Novel myeloma-associated antigens for peptide-based immunotherapy

针对多发性骨髓瘤（MM）的抗原特异性、基于T细胞的免疫疗法正在取得进展，进一步改善了这种仍然无法治愈的疾病的预后。这种免疫治疗概念在临床上有效应用的主要先决条件是鉴定和表征合适的mm相关抗原，以及能够产生抗原特异性t细胞反应的完整t细胞区室。虽然可行的胞外膜抗原有限，但来源于细胞内蛋白或结构域的HLA依赖抗原，通过HLA分子加工并呈现在肿瘤细胞表面，提供了大量潜在的肿瘤相关抗原选择。因此，在该项目的第一个资助期，我们使用基于质谱的方法表征了自然呈现的MM免疫肽球，并表征了几种新的非突变骨髓瘤相关抗原。我们首次进一步确定了所谓的“治疗相关”抗原，这些抗原是由特异性MM药物（例如蛋白酶体抑制剂）诱导的，因此可能代表了开发组合免疫疗法的极有希望的靶点。在本项目的第二个资助期内，我们的目标是扩大自然呈现的mm相关t细胞表位的选择，基于(I)突变衍生的HLA配体，（II）治疗相关的HLA配体和（III） mm相关膜抗原的细胞内结构域衍生的HLA配体的表征。此外，由于MM疾病的严重免疫缺陷可能会阻碍临床有效t细胞反应的诱导，我们的目标是在本项目中通过两种方式解决这个问题。首先，我们将描述未确定意义的单克隆γ病（MGUS）和阴燃骨髓瘤（SMM）的免疫肽丘及其在疾病进展过程中的改变，因为这些MM病的早期阶段显示功能T细胞与MM细胞的比例更完整，并且可能更有效地靶向T细胞免疫治疗方法。其次，我们将分析t细胞区室的治疗调节，使用免疫调节药物，免疫检查点抑制剂和CD38抗体daratumumab，以克服MM的免疫缺陷并优化抗原特异性t细胞反应。

Antigen-specific, T cell-based immunotherapies for multiple myeloma (MM) are on advance, further improving the outcome of this still incurable disease. The main prerequisites for the clinically effective application of such immunotherapy concepts is the identification and characterization of suitable MM-associated antigens, as well as an intact T-cell compartment capable to generate antigen-specific T-cell responses. While the repertoire of feasible extracellular membrane antigens is limited, HLA-dependent antigens derived from intracellular proteins or domains, which are processed and presented on the surface of tumor cells via HLA molecules provide a huge selection of potential tumor-associated antigens. Thus, in the first funding period of this project we characterized the naturally presented immunopeptidome of MM using a mass spectrometry-based approach and characterized several novel non-mutated myeloma-associated antigens. We further identified for the first time so called “treatment-associated” antigens that are induced by specific MM drugs like for example proteasome inhibitors, and therefore might represent highly promising targets for the development of combinatorial immunotherapies. Within the second funding period of this project we aim to expand the selection of naturally presented MM-associated T-cell epitopes, based on the characterization of (I) mutation-derived HLA ligands, (II) treatment-associated HLA ligands and (III) intracellular domain-derived HLA ligands of MM-associated membrane antigens. Further, as profound immune defects in established MM disease might hamper the induction of clinically effective T-cell responses, we aim to address this issue in two ways in this project. At first, we will characterize the immunopeptidome of monoclonal gammopathy of undetermined significance (MGUS) and smoldering myeloma (SMM), and its alteration during disease progression, as these preliminary stages of MM disease show a more intact ratio of functional T cells to MM cells and might more effectively be targeted by T-cell based immunotherapy approaches. Second, we will analyze therapeutic modulations of the T-cell compartment, using immunomodulatory drugs, immune checkpoint inhibitors and the CD38 antibody daratumumab, to overcome the immune defects in MM and optimize antigen-specific T-cell responses.