This 15 years old guy presented with left scapular mass 3 years ago , labeled as ewing sarcmoma. He was treated with 14 cession of Ifosfamide- base chemotherapy as well as involved field radiation. However, he developed multiple bone metastasis so the protocol shifted to irrinotecane+vincristine and then gemcitabine+ decetaxel due to stable disease. Despite 4 courses of GemDox protocol his bone metastasis have remained unchanged. what do you advise next for this poor guy?