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T细胞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识别和鉴定合适的MM相关抗原，以及能够产生抗原特异性T细胞反应的完整的T细胞室。虽然可行的胞外膜抗原的库是有限的，但来自细胞内蛋白或结构域的依赖于人类白细胞抗原的抗原，通过人类白细胞抗原分子被加工并呈现在肿瘤细胞表面，为潜在的肿瘤相关抗原提供了巨大的选择。因此，在这个项目的第一个资助期，我们用基于质谱学的方法表征了自然呈现的多发性骨髓瘤的免疫表位，并表征了几种新的非突变的骨髓瘤相关抗原。我们还首次确定了所谓的“治疗相关”抗原，这些抗原是由特定的多发性骨髓瘤药物诱导的，例如蛋白酶体抑制剂，因此可能是组合免疫疗法发展的极有希望的靶点。在这个项目的第二个资助期内，我们的目标是扩大自然呈现的多发性骨髓瘤相关T细胞表位的选择，其基础是(I)突变衍生的人类白细胞抗原配体，(Ii)治疗相关的人类白细胞抗原配体和(Iii)多发性骨髓瘤相关膜抗原的细胞内域衍生的人类白细胞抗原配体。此外，由于已建立的多发性骨髓瘤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，我们在这个项目中旨在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性伽马病(MGUS)和阴燃骨髓瘤(SMM)的免疫多肽及其在疾病进展过程中的变化，因为这些MM疾病的初始阶段显示出更完整的功能T细胞与MM细胞的比率，并可能更有效地成为基于T细胞的免疫治疗的靶点。其次，我们将使用免疫调节药物、免疫检查点抑制剂和CD38抗体Daratumab来分析T细胞亚群的治疗调节，以克服MM的免疫缺陷，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.