Regorafenib treatment for recurrent or refractory osteosarcoma

Abstract

We present the cases of two patients with recurrent or refractory (R/R) osteosarcoma, who received the multikinase inhibitor regorafenib. [Case 1] A 15-year-old male with right humerus osteosarcoma experienced disease progression during post-operative chemotherapy and started regorafenib treatment. He obtained partial response after one cycle of regorafenib treatment; however, his disease exacerbated again following nine cycles of the treatment. [Case 2] A 9-year-old male with right tibia osteosarcoma experienced frequent (pulmonary) relapses after initial treatment consisting of surgical resection of the primary tumor and preoperative and postoperative chemotherapy. He started regorafenib treatment after the fifth relapse. Although he had stable disease after two cycles of regorafenib, regorafenib treatment was terminated after four cycles owing to rapid progression of the disease. Both patients did not experience any severe adverse effects. Since the antitumor effect varies in different patients, data on genetic abnormalities to predict the efficacy of regorafenib for R/R osteosarcoma should be accumulated.