Malignant giant-cell tumors are extremely rare bone sarcomas that transform from conventional giant-cell tumors during long periods of treatment. Owing to their rarity, no further analysis of their molecular pathogenesis exists, and thus, no standard treatment has been established. Recently, organoid culture methods have been highlighted for recapturing the tumor microenvironment, and we have applied the culture methods and succeeded in establishing patient-derived organoids (PDO) of rare sarcomas. This study aimed to investigate the genomic characteristics of our established novel organoids from human malignant giant-cell tumors. At our institute, we treated a patient with malignant giant-cell tumor. The remaining sarcoma specimens after surgical resection were cultured according to the air–liquid interface organoid-culture method. Organoids were xenografted into NOD-scid IL2Rgnull mice. The developed tumors were histologically and genomically analyzed to compare their characteristics with those of the original tumors. Genetic changes over time throughout treatment were analyzed, and the genomic status of the established organoid was confirmed. Organoids from malignant giant-cell tumors could be serially maintained using air–liquid interface organoid-culture methods. The tumors developed in xenografted NOD-scid IL2Rgnull mice. After several repetitions of the process, a patient-derived organoid line from the malignant giant-cell tumor was established. Immunohistochemical analyses and next-generation sequencing revealed that the established organoids lacked the H3-3A G34W mutation. The xenografted organoids of the malignant giant-cell tumor had phenotypes histologically and genetically similar to those of the original tumor. The established organoids were confirmed to be derived from human malignant giant-cell tumors. In summary, the present study demonstrated a novel organoid model of a malignant giant-cell tumor that was genetically confirmed to be a malignant transformed tumor. Our organoid model could be used to elucidate the molecular pathogenesis of a malignant giant-cell tumor and develop novel treatment modalities.

恶性巨细胞瘤是极为罕见的骨肉瘤，在长期治疗过程中从传统的巨细胞瘤转变而来。由于它们的稀有性，没有对其分子发病机制的进一步分析，因此没有建立标准治疗方法。最近，类器官培养方法被强调用于重新捕获肿瘤微环境，我们应用这些培养方法并成功地建立了罕见肉瘤的患者来源的类器官 (PDO)。本研究旨在研究我们从人类恶性巨细胞肿瘤中建立的新型类器官的基因组特征。在我们研究所，我们治疗了一名恶性巨细胞瘤患者。根据气液界面类器官培养法培养手术切除后剩余的肉瘤标本。类器官被异种移植到 NOD-scid IL2Rgnull 小鼠中。对发展的肿瘤进行组织学和基因组分析，以将它们的特征与原始肿瘤的特征进行比较。分析了整个治疗过程中随时间发生的遗传变化，并确认了已建立的类器官的基因组状态。来自恶性巨细胞肿瘤的类器官可以使用气液界面类器官培养方法连续维持。肿瘤在异种移植的 NOD-scid IL2Rgnull 小鼠中发展。经过几次重复该过程，建立了来自恶性巨细胞瘤的患者来源的类器官系。免疫组织化学分析和下一代测序表明，已建立的类器官缺乏 对发展的肿瘤进行组织学和基因组分析，以将它们的特征与原始肿瘤的特征进行比较。分析了整个治疗过程中随时间发生的遗传变化，并确认了已建立的类器官的基因组状态。来自恶性巨细胞肿瘤的类器官可以使用气液界面类器官培养方法连续维持。肿瘤在异种移植的 NOD-scid IL2Rgnull 小鼠中发展。经过几次重复该过程，建立了来自恶性巨细胞瘤的患者来源的类器官系。免疫组织化学分析和下一代测序表明，已建立的类器官缺乏 对发展的肿瘤进行组织学和基因组分析，以将它们的特征与原始肿瘤的特征进行比较。分析了整个治疗过程中随时间发生的遗传变化，并确认了已建立的类器官的基因组状态。来自恶性巨细胞肿瘤的类器官可以使用气液界面类器官培养方法连续维持。肿瘤在异种移植的 NOD-scid IL2Rgnull 小鼠中发展。经过几次重复该过程，建立了来自恶性巨细胞瘤的患者来源的类器官系。免疫组织化学分析和下一代测序表明，已建立的类器官缺乏 并确认了已建立的类器官的基因组状态。来自恶性巨细胞肿瘤的类器官可以使用气液界面类器官培养方法连续维持。肿瘤在异种移植的 NOD-scid IL2Rgnull 小鼠中发展。经过几次重复该过程，建立了来自恶性巨细胞瘤的患者来源的类器官系。免疫组织化学分析和下一代测序表明，已建立的类器官缺乏 并确认了已建立的类器官的基因组状态。来自恶性巨细胞肿瘤的类器官可以使用气液界面类器官培养方法连续维持。肿瘤在异种移植的 NOD-scid IL2Rgnull 小鼠中发展。经过几次重复该过程，建立了来自恶性巨细胞瘤的患者来源的类器官系。免疫组织化学分析和下一代测序表明，已建立的类器官缺乏H3-3A G34W 突变。恶性巨细胞瘤的异种移植类器官在组织学和遗传学上具有与原始肿瘤相似的表型。已建立的类器官被证实来源于人类恶性巨细胞瘤。总之，本研究展示了一种新的恶性巨细胞瘤类器官模型，该模型经基因证实为恶性转化肿瘤。我们的类器官模型可用于阐明恶性巨细胞瘤的分子发病机制并开发新的治疗方式。