BONSAI-2 study: Nivolumab as therapeutic option after cabozantinib failure in metastatic collecting duct carcinoma patients.

Background: The BONSAI phase II trial recently demonstrated the activity of cabozantinib in metastatic collecting duct patients. The outcomes of patients in this setting treated with immunotherapy as second-line is unknown. The aim of the present report was to describe outcomes of patients enrolled in the BONSAI trial that received nivolumab as second-line treatment.
Material and Methods: We describe the oncological outcomes in terms of overall response rate, progression-free survival, overall survival and safety. We excluded patients that did not receive any second-line treatment or were treated with agents other than nivolumab.
Results: We identified five patients of whom one was excluded due to lack of data. Three patients obtained clinical benefit (one partial response, two stable disease); the second-line progression-free survival (nivolumab) ranged from 2.8 to 19.9 months to and second-line overall survival ranged from 5.1 to 26.5 months. No new safety signals were observed.
Conclusions: Nivolumab may be considered as second-line therapy option after cabozantinib failure in selected metastatic collecting duct carcinoma patients.