Planned Abscopal Effect with Concurrent Pembrolizumab and Ablative Radiotherapy to Pulmonary Metastasis: A Case Report and Review of the Literature.

Most abscopal effects are reported as sporadic and unpredictable events following radiotherapy at symptomatic sites. Herein, we report a case in which a planned abscopal effect was induced following deliberate radiotherapy and concurrent systemic immunotherapy. A 53-year-old man with a combined positive score ≥10 developed extensive metastatic bladder cancer after progressing on conventional chemotherapy. Extensive metastases were identified in his liver, lungs, and bones. He later had four cycles of single-agent pembrolizumab and planned hypofractionated radiotherapy at an ablative dose to selected metastatic lung tumors and developed complete remission of disease even when pembrolizumab was discontinued. This is a clear demonstration that the abscopal effect could be harnessed in a systematic manner with a combined positive score and aggressive local radiotherapy.