Ewing sarcoma (EWS) is a malignant tumour of bone and soft tissue, and although many patients are cured with conventional multimodal therapy, those with recurrent or metastatic disease have a poor prognosis. Genomic instability and programmed cell death ligand-1 (PD-L1) expression have been identified in EWS, providing a rationale for treatment with agents that block the programmed cell death-1 (PD-1) receptor.

In this report, we describe a heavily pre-treated patient with recurrent metastatic EWS who achieved a clinical and radiological remission with PD-1 blockade.

To our knowledge, this is the first reported case demonstrating efficacy of PD-1 blockade in EWS. This warrants further investigation in particular given the poor prognosis in patients with recurrent or metastatic disease.