Apatinib Combined With Liposomal Irinotecan for Refractory or Metastatic Osteosarcoma

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.

Osteosarcoma is the most common primary malignant bone tumor in adolescents and young adults. Although multimodal treatment including surgery and multi-agent chemotherapy has improved survival for patients with localized disease, the prognosis of patients with recurrent or metastatic osteosarcoma remains poor. Targeting tumor angiogenesis has emerged as a promising therapeutic strategy for osteosarcoma. Apatinib is an oral small-molecule tyrosine kinase inhibitor that selectively inhibits VEGFR-2 and has demonstrated clinical activity in advanced osteosarcoma in previous studies. Irinotecan is a topoisomerase I inhibitor with antitumor activity in several malignancies. Liposomal irinotecan is a nanoliposomal formulation that improves the pharmacokinetic profile and intratumoral delivery of irinotecan, potentially enhancing its antitumor effect. This investigator-initiated study is designed to evaluate the safety, tolerability, and preliminary efficacy of apatinib combined with liposomal irinotecan in patients with recurrent or refractory osteosarcoma. Patients will receive oral apatinib daily in combination with intravenous liposomal irinotecan administered every two weeks until disease progression, unacceptable toxicity, or withdrawal of consent. The primary objective is to evaluate the safety and tolerability of the combination therapy. Secondary objectives include evaluation of antitumor activity such as objective response rate, progression-free survival, and overall survival.