Multicenter retrospective real-world study of tyrosine kinase inhibitors for relapsed or refractory bone tumors

Depending on location and timing of relapse, traditional approaches to second line therapy for bone tumors have been dominated by cytotoxic chemotherapies; however the outcomes are poor. Recently published studies reported encouraging outcomes with tyrosine kinase inhibitors (TKIs). The Canadian multicenter retrospective CanSaRCC (‘Canadian sarcoma research and clinical collaboration’) study evaluated regorafenib or cabozantib for relapsed or refractory osteosarcoma, Ewing sarcoma, or chondrosarcoma/extraskeletal mesenchymal chondrosarcoma. The TKIs had meaningful activity, with median overall survival ranging from 8.1 months (chondrosarcoma) to 18.2 months (extraskeletal mesenchymal chondrosarcoma ). Dose reduction was required in 42.4% of patients. Age, line of therapy, regorafenib versus cabozantinib, and time from diagnosis tot initiation of TKI were not associated with progression-free survival.