MTOR and bone sarcoma: Regarding the PI3K/AKT/mTOR pathway, the mTOR inhibitor ridaforolimus was investigated mainly for sarcoma; a phase 3 trial of ridaforolimus showed the prolongation of PFS in sarcoma patients (mainly STS patients, but some bone sarcoma patients were included in this study) in the maintenance setting after chemotherapy, but the clinical benefit was too small to result in approval [74].