The abscopal effect in head-and-neck squamous cell carcinoma treated with radiotherapy and nivolumab: A case report and literature review

Abstract

Introduction The abscopal effect is a rarely observed outcome of radiotherapy wherein there is a reduction in metastatic disease burden outside of the targeted treatment area. Likely due to an in situ vaccine effect of radiother-apy, the abscopal effect may be augmented by immunotherapy. This report is the first case of the abscopal effect observed in metastatic head-and-neck squamous cell carcinoma (hnscc) treated with concurrent radiotherapy and single-agent nivolumab. Case Description An otherwise healthy 57-year-old man underwent craniofacial resection and adjuvant chemo-radiotherapy for advanced sinonasal squamous cell carcinoma. Distant metastatic disease developed shortly after primary treatment, and immunotherapy in the form of nivolumab was initiated. Subsequent oligometastatic progres-sion despite immunotherapy prompted palliative radiotherapy to a single metastasis due to pending symptomatology. Post-radiotherapy, the abscopal effect was observed with all distant sites of metastatic disease shrinking. Five months following treatment, a sustained reduction in disease burden has been demonstrated. Summary We present the first case of the abscopal effect in a patient with metastatic hnscc treated with palliative radiotherapy concurrent with single-agent nivolumab immunotherapy, and only the third case of the abscopal effect in metastatic head-and-neck cancer. Dual treatment with immunotherapy and radiotherapy may be an important treatment option in the future, mediated through the abscopal effect.