Treatment-Free Survival After Discontinuation Of Immuno-Checkpoint Therapy, And Outcome Of Subsequent Molecular Targeted Therapy: Retrospective Study Of Japanese Metastatic Renal Cell Carcinoma Patients (After I-O Study)

677 Background: Guidelines for treatment of metastatic renal cell carcinoma (mRCC) recommend nivolumab monotherapy (NIVO) for treated mRCC, and nivolumab + ipilimumab combination therapy (NIVO+IPI) for untreated IMDC intermediate and poor risk mRCC patients. Though molecular targeted therapies (TTs) such as VEGFR-TKIs and mTORi are recommended as subsequent therapy after NIVO or NIVO+IPI, their impact is still unclear. Methods: Japanese mRCC patients treated with TT after NIVO (CheckMate 025) or NIVO+IPI (CheckMate 214) were retrospectively analyzed. Primary endpoints were investigator assessed ORR of the first TT after NIVO, and after NIVO+IPI. Secondary endpoints included treatment-free survival (TFS) after discontinuation of NIVO and NIVO+IPI, and progression-free survival (PFS) and safety of the first subsequent TT after NIVO and NIVO+IPI. Results: Twenty-six patients of CheckMate 025 and 19 patients of CheckMate 214 from 20 centers in Japan were analyzed. Median TFS after ICI discontinuation was 1.0m and 2.5m for CheckMate 025 and CheckMate 214 patients, respectively. Median follow-up period from the start of TT after ICI discontinuation to date of analysis or death was 22.1m for CheckMate 025, and 20.3m for CheckMate 214 patients. As the first subsequent TT after NIVO or NIVO+IPI, axitinib was the most treated therapy for both CheckMate 025 (53.8%) and CheckMate 214 (47.4%) patients. ORR of TT after NIVO and NIVO+IPI was 26.9% and 31.6%, and median PFS was 8.9m and 16.3m, respectively. During the treatment of first TT after NIVO and NIVO+IPI, 98% percent experienced treated-related adverse events, 51% experienced grade 3-4, but no treatment related death. Conclusions: TTs have favorable antitumor activity for mRCC after NIVO and NIVO+IPI, possibly by changing the mode of action. Safety signals of TTs after ICI were similar to the previous reports. These results indicate sequential TTs after ICI may contribute for durable survival benefit.