RESUMO
Rhabdomyosarcoma (RMS) is the most common highly malignant pediatric soft tissue sarcoma. While recent multidisciplinary treatments have improved the 5year survival rate of low/intermediaterisk patients to 7090%, there are various complications that arise due to treatmentrelated toxicities. Immunodeficient micederived xenograft models have been widely used in cancer drug research; however, these models have some limitations, including i) they are timeconsuming and expensive, ii) their use needs to be approved by animal experimental ethics committees, and iii) the inability to visualize where tumor cells or tissues were engrafted. The present study performed a chorioallantoic membrane (CAM) assay in fertilized chicken eggs, which is timesaving, simple, and easy to standardize and handle because of the high vascularization and the immature immune system of the fertilized eggs. The present study aimed to examine the usability of the CAM assay as a novel therapeutic model for the development of precision medicine for pediatric cancer. A protocol was developed for constructing cell linederived xenograft (CDX) models using a CAM assay by transplanting RMS cells on the CAM. It was then examined as to whether these CDX models could be used as therapeutic drug evaluation models using vincristine (VCR) and human RMS cell lines. After grafting and culturing the RMS cell suspension on the CAM, threedimensional proliferation over time was observed visually and by comparing volumes. VCR reduced the size of the RMS tumor on the CAM in a dosedependent manner. Currently, treatment strategies based on patientspecific oncogenic backgrounds have not been adequately developed in the field of pediatric cancer. The establishment of a CDX model with the CAM assay may lead to the advancement of precision medicine and help formulate novel therapeutic strategies for intractable pediatric cancer.