Abstract
Myxofibrosarcoma is a rare tumor, refractory to cytotoxic chemotherapy and radiotherapy. Pembrolizumab is an innovative immunotherapy drug consisting of programmed death receptor ligand 1 antibody proven to be useful for numerous types of cancer cells. A patient had been diagnosed with metastatic myxofibrosarcoma, refractory to radiotherapy and conventional cytotoxic chemotherapy. The patient achieved a partial response during palliative chemotherapy with pembrolizumab for 14 cycles. To the best of our knowledge, this is the first case report demonstrating the efficacy of pembrolizumab for refractory myxofibrosarcoma.