A perspective on patient-derived orthotopic xenograft (PDOX) mouse models for identification of novel and individualized treatment for sarcoma.

Sarcomas, including osteosarcoma and soft tissue sarcoma, are heterogeneous and rare diseases with limited treatment options and a high metastatic potential. Despite advancements in immunotherapy and targeted therapies, many sarcoma patients have limited durable responses to these treatments. Therefore, individualized precision medicine and novel drug discovery are greatly needed. To address this unmet need, we have developed a patient-derived orthotopic xenograft (PDOX) mouse model of sarcomas using surgical orthotopic implantation. The PDOX models more accurately recapitulate the complex characteristics of human tumors compared to traditional subcutaneous xenografts. This enhanced fidelity is due to the preservation of the original tumor's histology and the accurate representation of the tumor microenvironment within the orthotopic implantation site. The present report summarizes our research group's experience with the sarcoma PDOX model and underscores its significant potential for identifying effective therapeutics. We have obtained numerous promising and unexpected results, including the identification of active chemotherapy drugs, novel drug combinations, and experimental therapeutics tailored to individual patients. In the current era of growing advancements in precision medicine, PDOX models offer a unique opportunity for developing individualized and innovative therapy specifically tailored to the individual needs of sarcoma patients.