PIK3CB and neoplasm: To test whether the increased infiltration of PD‐1+ T cells upon dual PI3K/mTOR inhibition could sensitise tumours to ICB‐based therapy in vivo, we treated CD34+ humanized EMC041 PDXs with: (i) nivolumab (anti‐PD‐1), (ii) alpelisib + sapanisertib, (iii) nivolumab + alpelisib + sapanisertib or (iv) vehicle.