The long-term effectiveness of immunotherapies against Multiple Myeloma (MM) remains elusive, demonstrated by the inevitable relapse in patients. This underscores the urgent need for an in-depth analysis of the MM tumor-immune microenvironment (TME). Hereto, a representative immunocompetent MM mouse model can offer a valuable approach to study the dynamic changes within the MM-TME and to uncover potential resistance mechanisms hampering effective and durable therapeutic strategies in MM. We generated a comprehensive single-cell RNA-sequencing atlas of the MM-TME in bone marrow and spleen encompassing different stages of disease, using the immunocompetent 5T33MM mouse model. Through comparative analysis, we correlated our murine dataset with the pathogenesis in MM patients by reanalyzing publicly available datasets of human bone marrow samples across various disease stages. Using flow cytometry, we validated the dynamic changes upon disease progression in the 5T33MM model. Furthermore, interesting target populations, as well as the immune-boosting anti-CD40 agonist (αCD40) therapy were tested ex vivo on murine and human primary samples and in vivo using the 5T33MM model. In this study, we identified the heterogenous and dynamic changes within the TME of murine and human MM. We found that the MM-TME was characterized by an increase in T cells, accompanied with an exhausted phenotype. Although neutrophils appeared to be rather innocuous at early disease stages, they acquired a pro-tumorigenic phenotype during MM progression. Moreover, conventional dendritic cells (cDCs) showed a less activated phenotype in MM, underscoring the potential of immune-boosting therapies such as αCD40 therapy. Importantly, we provided the first pre-clinical evaluation of αCD40 therapy and demonstrated successful induction of cDC- and T-cell activation, accompanied by a significant short-term anti-tumor response. This resource provides a comprehensive and detailed immune atlas of the evolution in human and murine MM disease progression. Our findings can contribute to immune-based patient stratification and facilitate the development of novel and durable (immune) therapeutic strategies in MM.

中文翻译：

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跨疾病阶段的小鼠和人多发性骨髓瘤免疫微环境的单细胞转录组图谱


免疫疗法对多发性骨髓瘤 （MM） 的长期有效性仍然难以捉摸，患者不可避免的复发证明了这一点。这凸显了对 MM 肿瘤免疫微环境 （TME） 进行深入分析的迫切需求。在此，具有代表性的免疫活性 MM 小鼠模型可以提供一种有价值的方法来研究 MM-TME 内的动态变化，并揭示阻碍 MM 有效和持久治疗策略的潜在耐药机制。我们使用免疫功能正常的 5T33MM 小鼠模型在骨髓和脾脏中生成了 MM-TME 的综合单细胞 RNA 测序图谱，包括疾病的不同阶段。通过比较分析，我们通过重新分析不同疾病阶段的公开可用的人骨髓样本数据集，将小鼠数据集与 MM 患者的发病机制相关联。使用流式细胞术，我们验证了 5T33MM 模型中疾病进展的动态变化。此外，有趣的靶标人群以及免疫增强抗 CD40 激动剂 （αCD40） 疗法在小鼠和人类原始样本上进行了离体测试，并使用 5T33MM 模型在体内进行了测试。在这项研究中，我们确定了小鼠和人 MM 的 TME 内的异质性和动态变化。我们发现 MM-TME 的特征是 T 细胞增加，伴随着耗竭的表型。尽管中性粒细胞在疾病早期似乎相当无害，但它们在 MM 进展期间获得了促肿瘤表型。此外，传统的树突状细胞 （cDC） 在 MM 中显示出激活程度较低的表型，这强调了免疫增强疗法（如 αCD40 疗法）的潜力。 重要的是，我们提供了 αCD40 疗法的首次临床前评估，并证明成功诱导 cDC 和 T 细胞活化，并伴有显着的短期抗肿瘤反应。该资源提供了人类和小鼠 MM 疾病进展进化的全面而详细的免疫图谱。我们的研究结果有助于基于免疫的患者分层，并促进 MM 中新型和持久（免疫）治疗策略的开发。