1895P Time to treatment failure (TTF) and treatment beyond progression (TBP) in pretreated metastatic renal cell carcinoma (mRCC) patients (pts) receiving nivolumab: A survival outcome and a therapeutic strategy of clinical benefit (meet-uro 15)

Immunotherapy is associated with different response patterns compared with chemotherapy and targeted therapy, including delayed response and stabilization after disease progression. In clinical practice, immunotherapy can be continued after radiological progression when clinical benefit is observed. Therefore, progression-free survival (PFS), calculated with the first disease progression, may not express the real benefit derived from immunotherapy. The Meet-URO 15 study was a multicentric retrospective analysis on 571 pretreated mRCC pts receiving nivolumab. TTF was defined as the time from start of therapy to the definitive disease progression which changed the therapeutic line or death. The comparison between TTF and PFS and the prognostic performance of the Meet-URO score versus (vs) the IMDC score according to TTF and PFS were assessed. Moreover, response and survival outcomes between TBP pts and non-TBP pts were evaluated. 571 pts were included in the analyses (PMID: 34046089). Median TTF was 8.9 months (range: 7.2-10.2) and mPFS was 7.2 months (range: 5.8-8.6). The Meet-URO score performed better than the IMDC score in both TTF (c index: 0.63 vs 0.59) and PFS (0.62 vs 0.59). TBP pts were associated with higher overall response rate (34.4% vs 23.6%; p = 0.035) and disease control rate (61.3% vs 54.8%; p = 0.30). Moreover, TBP pts interestingly correlated with longer TTF (25.0 vs 10.7 months; p<0.001) and OS (42.5 vs 26.7 months; p<0.001), but had similar PFS compared with non-TBP pts. In TBP pts, a mean delay of 13.2 months (range: 6-20.4) from first to definitive disease progression was observed (25 vs 11.8 months), while non-TBP pts had overlapped TTF and PFS (10.8 months). In pretreated mRCC pts receiving nivolumab, a small difference between mTTF and mPFS (∼2 months) was observed in the overall population. However, TBP pts were associated with significantly better ORR (+10%), TTF (+13 months) and OS (+ 15.8 months). Moreover, the Meet-URO score prognostically performed better with TTF than with PFS and compared with the IMDC score in both survival outcomes.