Comparison of MAPI+Camrelizumab Versus API+Apatinib Versus MAPI in Patients With a Poor Response to Preoperative Chemotherapy for Newly Diagnosed High-grade Osteosarcoma

Treatment strategies for high-grade osteosarcoma with multidrug chemotherapy and resection result in 3-year event-free survival of 60-70%. The most common factors predicting survival are presence of metastases, histological response to preoperative chemotherapy and complete surgical resection. Four of the active drugs in osteosarcoma include cisplatin, doxorubicin, high-dose methotrexate and ifosfamide and this combination (MAPI), given preoperatively and postoperatively, is widely used for the treatment of osteosarcoma in China. Apatinib also has activity in advanced setting and when incorporated into the treatment of patients with metastatic disease seemed to improve progression-free survival. Combination of apatinib and camrelizumab resulted in durable therapuetic effect in selected cases. Though EURAMOUS-1 suggested that changing chemotherapy postoperatively on the basis of histological response did not improve outcomes. The exploratory study with radomised design to compare combination of chemotherapy with target drug or combination of chemotherapy with anti-PD-1 antibody versus standard chemotherapy has not been tried yet. Thus we aim to investigate the efficacy and toxicity of these combiantions versus standard chemotherapy in this study.