181P Intratumoral heterogeneity of immune infiltrate in leiomyosarcomas

Background: Exercise training reduces tumour growth by increasing tumour-infiltrating T cell density in preclinical models.However, it remains unknown whether exercise training can modify intratumoural T cells in humans.Objective: To compare the effects of exercise training intervention versus control on human prostate intratumoural T cell density.Methods: This study is a secondary analysis of a randomised controlled trial.We randomly allocated men (age >18 years) with treatment-nave localized prostate cancer scheduled to radical prostatectomy 2:1 to exercise training intervention or control.The exercise intervention consisted of supervised, high-intensity interval bicycling four times per week from the time of randomization until prostatectomy.Intratumoural CD3 + and CD8 + T cell densities in diagnostic biopsies and post-surgical prostatectomy specimens were quantified using immunohistochemistry. Betweengroup differences in changes from baseline to follow-up were estimated using constrained baseline linear mixed-effect models.