In advanced osteosarcoma where traditional chemotherapy has failed, the multi-targeted tyrosine kinase inhibitor apatinib has become a mainstream systemic treatment option in China. However, for patients with a high tumor burden or extra-pulmonary lesions, these drugs are prone to secondary resistance, necessitating combination with chemotherapy for more effective comprehensive control. Liposomal irinotecan, a newly approved topoisomerase inhibitor, exhibits lower toxicity compared to traditional irinotecan and is one of the second-line chemotherapy agents for osteosarcoma, making it a suitable candidate for combination therapy with apatinib.
The primary objective of this study is to determine the optimal regimen of apatinib combined with liposomal irinotecan injection, while the secondary objective is to evaluate the safety and efficacy of this combination in patients with refractory osteosarcoma who have progressed after second-line chemotherapy.