Pazopanib in the Treatment of Bone Sarcomas: Clinical Experience.

Background: The effect of chemotherapy in metastatic bone sarcomas is poor and the condition is invariably fatal. Therefore, new treatment modalities are intensely needed. Pazopanib is a selective multitargeted tyrosine kinase inhibitor that has proven to be effective in the treatment of metastatic soft tissue sarcomas. The objective of this study was to evaluate the off-label use of pazopanib in patients with metastatic bone sarcomas who failed standard chemotherapy.

Methods: All patients with metastatic bone sarcomas treated with pazopanib between October 1st, 2011 and October 1st, 2017 at the Department of Oncology, Aarhus University Hospital were evaluated. Demographics, treatment, and survival outcomes were collected and analyzed.

Results: Nineteen patients were identified. The median age was 38 years (range 18-62). Most of the patients (50%) were diagnosed with osteosarcoma. All patients had documented disease progression at the time of initiating pazopanib treatment. The median overall survival was 11 months. Median progression free survival was 5.4 months. Out of 19 patients, 13 (68%) had either partial response or stable disease. In five patients, the dose of pazopanib was reduced because of toxicity.

Conclusion: Off-label use of pazopanib is effective in the treatment of metastatic bone sarcomas of different histologies. Pazopanib was well tolerated in the treatment of patients with refractory bone sarcomas. Studies examining the effect of pazopanib alone or in combination with chemotherapy or other targeted therapies are needed.