Clinical Factors That Affect the Establishment of Soft Tissue Sarcoma Patient-Derived Orthotopic Xenografts: A University of California, Los Angeles, Sarcoma Program Prospective Clinical Trial

PurposeGiven the diverse and aggressive nature of soft tissue sarcomas (STSs), a need exists for more-precise therapy. Patient-derived orthotopic xenografts (PDOXs) provide a unique platform for personalized treatment. Thus, identification of patient and treatment factors that predict PDOX establishment is important. This study assessed the feasibility of incorporating PDOXs into the clinical setting and identifying factors associated with PDOX establishment.Patients and MethodsFrom May 2015 to May 2016, 107 patients with biopsy-proven or potential STS were enrolled. Tumor samples were obtained intraoperatively and orthotopically implanted into nude mice in the corresponding anatomic location. PDOXs were considered established after engraftment and serial passage. Factors associated with establishment were analyzed by logistic regression and time to establishment by time-to-event analysis.ResultsOnly high-grade tumors established (32 of 72 [44.4%]). The establishment rate (ER) varied by neoadjuvant therap...