Longitudinal biopsies of fusion-positive rhabdomyosarcoma orthotopic xenografts

In this experiment, 3 mice were implanted orthotopically with a patient-derived xenograft, SJRHB013759_X14. After tumor engraftment and visible nodule formation, all 3 mice underwent therapy. One mouse received vehicle control (saline), while two mice were treated with a combination of vincristine and irinotecan, to mimic salvage therapy for relapsed rhabdomyosarcoma. Sedated needle biopsies were performed before (time = 0), during therapy (time = 3, 7, and 14 days), and after recurrence.