• Pathological diagnosis of high-grade osteosarcoma(cohort I),dedifferentiated liposarcoma or polytypic liposarcoma(cohort II),unsuitable for local treatment;

• The requirements for front-line treatment received by subjects are as follows:

‣ Subjects with osteosarcoma have failed at least first-line chemotherapy and are not suitable for re-receiving first-line chemotherapy ,or progression within 6 months of the end of first-line therapy;

⁃ Subjects with dedifferentiated liposarcoma or polytype liposarcoma who have received at least first-line chemotherapy failure for recurrent/metastatic sites or relapse during postoperative adjuvant chemotherapy or within 6 months after treatment(considered first-line treatment failure).