Immunotherapy retreatment: case report, review of the literature and proposal for the definition of different scenarios.

Immune checkpoint inhibitors have improved the treatment landscape of different tumors and one of the emerging issues is the reintroduction of immunotherapy after discontinuation. Scarce evidence is currently available and different definitions have been used. The case of a patient with pretreated advanced urothelial cancer, who responded to immunotherapy retreatment after long-term benefit from the previous course, is reported. Based on a review of the different clinical scenarios, a definition of immunotherapy retreatment was proposed, as rechallenge or reintroduction, based on the reasons of discontinuation of the previous course. Clinical factors potentially associated with clinical benefit from immunotherapy retreatment are discussed, even though ad hoc studies are needed to assess the efficacy and safety of the different immunotherapy retreatment strategies.