Efficacy of treatment beyond third-line (3L) in metastatic clear-cell renal cell carcinoma (mccRCC)

647 Background: During the last decade, 10 agents have been approved for the treatment of patients (pts) with mccRCC, and guidelines have been developed up to 3L. The aim of the study is to describe the potential benefit of therapies beyond 3L in clinical practice Methods: Retrospective data analysis was performed using IGRECC (Institut Gustave Roussy REnal Cell Carcinoma) database to describe clinical features and outcomes beyond 3L in mccRCC. Kaplan Meier estimation was applied for progression free survival (PFS) and overall survival (OS) Results: Between 2005 and 2016, 825 (80%) pts had mccRCC and were treated with targeted therapies, of which 517 (63%) had 2L, 271 (33%) had 3L, 145 (18%) had 4L and 75 (9%) had 5L of therapy. Baseline characteristics and treatments are displayed in Table 1. With a median follow-up of 29 months (mo) (min: 20 max: 51), for patients receiving 4L, the median PFS is 5 mo (95%CI 4 – 6) and the median OS is 15.5 mo (95%CI 12 – 21). Pts with International Metastatic Renal Cell Cancer Database Consortium (IMDC) score favourable (18%), intermediate (59%), and poor risk (23%) at 4L initiation had a median OS of 24 mo (95%CI 11 – NR), 16 mo (95%CI 12.6 – 24), and 8 mo (95%CI 6 – 15), respectively (p < 0.0036). Partial response (PR) and stable disease (SD) were achieved in 13% and 56% of 122 evaluable pts. With a median follow-up of 16 mo (min: 13 max: 37) in 5L, the median PFS is 4.5 mo (95%CI 3 – 6) and the median OS is 19.5 mo (95%CI 11 - 28). Pts with a poor IMDC score risk at 5L initiation (33%) had a median OS of 7 mo (95%CI 3 – 10) (p < 0.0001). PR and SD were achieved in 16% and 52% of 55 evaluable pts in 5L Conclusions: The approved agents remain active as 4L or 5L options for mccRCC in pts who can reach this situation. Interestingly, both PFS and OS appear to be very similar in 4L and 5L as compared to 3L. Therefore, we believe that selected pts may derive benefit from these treatments beyond the barriers of regulatory or reimbursement approval [Table: see text]