Abscopal effect after hypofractionated radiotherapy in metastatic renal cell carcinoma pretreated with pazopanib.

Background:The abscopal effect consists of distant metastases response after local treatment based on systemic immune stimulation. It is a rare event observed in many tumors, especially with radiotherapy and immunotherapy.Clinical case:We report the long-term abscopal effect in a metastatic renal cell carcinoma patient with lung metastasectomy, after hypofractionated radiotherapy on lymph node metastasis. The patient was pretreated with pazopanib, which was discontinued early owing to toxicity before radiotherapy.Methodology:Immunohistological analyses of the primary tumor and metastases were performed.Discussion:We supposed that radiotherapy, and maybe tyrosine kinase inhibitors, could act as immune-primers for abscopal effect modifying the immune tumor microenvironment.Conclusion:Future studies are needed to optimize the combination of radiotherapy with systemic therapy for better long-term tumor control in selected patients.