Mesenchymal tumor organoid models recapitulate rhabdomyosarcoma subtypes

Rhabdomyosarcomas (RMS) are mesenchyme-derived tumors and the most common childhood soft tissue sarcomas. Treatment is intense, with a nevertheless poor prognosis for high-risk patients. Discovery of new therapies would benefit from additional preclinical models. Here we describe the generation of a collection of 19 pediatric RMS tumor organoid (tumoroid) models (success rate of 41%) comprising all major subtypes. For aggressive tumors, tumoroid models can often be established within four to eight weeks, indicating the feasibility of personalized drug screening. Molecular, genetic and histological characterization show that the models closely resemble the original tumors, with genetic stability over extended culture periods of up to six months. Importantly, drug screening reflects established sensitivities and the models can be modified by CRISPR/Cas9 with TP53 knockout in an embryonal RMS model resulting in replicative stress drug sensitivity. Tumors of mesenchymal origin can therefore be used to generate organoid models, relevant for a variety of preclinical and clinical research questions.

横纹肌肉瘤（Rhabdomyosarcomas, RMS）是一类间叶来源性肿瘤，亦是儿童最常见的软组织肉瘤。其临床治疗方案强度较高，但高危患者的预后仍欠佳。新型治疗手段的研发亟需更多优质临床前模型支撑。本研究构建了涵盖所有主要亚型的19株儿童横纹肌肉瘤肿瘤类器官（tumoroid）模型，构建成功率达41%。对于侵袭性肿瘤，通常可在4至8周内完成类器官模型构建，这证明了个性化药物筛选的可行性。分子、遗传及组织学表征分析显示，该类器官模型与原始肿瘤高度相似，且在长达6个月的长期培养过程中可维持遗传稳定性。尤为关键的是，药物筛选结果可准确反映肿瘤已明确的药物敏感性；此外，可通过CRISPR/Cas9技术对模型进行基因编辑，例如在胚胎型横纹肌肉瘤模型中敲除TP53基因，可使其获得复制应激药物敏感性。综上，间叶来源性肿瘤可用于构建类器官模型，该模型可适配多种临床前及临床研究场景。