Concordance between orthotopic-patient derived xenograft models and patient treatment responses

e23553 Background: Patient-derived xenografts (PDX) have shown promise in identifying personalized therapies for cancer patients. We have previously shown that orthotopic-PDX models from untreated, high-grade sarcomas demonstrate a 62% establishment rate with a median time of 54 days. Methods: We performed a retrospective study by collecting oncologic patient treatment history and response data to carry out in vivo pharmacology studies on corresponding O-PDX models using therapies that the patients received. Results: Among 16 patients and 26 therapies, we identified an overall concordance of 84.6%. Specifically, we show a positive predictive value of 82.4% among responders and a negative predictive value of 88.9% among non-responders. Conclusions: This study demonstrates that O-PDX models replicate clinical response in patients and are valuable screening platforms for guiding therapeutic decision-making for rare cancers such as sarcoma.