Abscopal effect following checkpoint inhibitor therapy and localized radiotherapy for metastatic clear cell renal cell carcinoma: A case report.

We present the case of a 64-year-old patient with metastatic renal cell carcinoma, who experienced disease progression despite undergoing multiple lines of systemic therapy, including immune checkpoint inhibitors (ICI). Two months after stereotactic radiosurgery to his brain lesions and while the patient was not on any systemic therapy, restaging scans demonstrated a dramatic near complete regression of the primary renal lesion and metastatic sites, which was attributed to the abscopal effect, mediated by the exposure to ICI and radiotherapy. While its mechanisms are not fully understood, it is believed to stem from the tumor immunosuppression and immunogenicity induced by radiation.