Improvements in first-line systemic mRCC therapy: Challenging insights from a cross trial comparison of overall survival and subsequent therapies in recent phase III trials

705 Background: Using sunitinib (SUN) as the comparator, two out of three recent phase III clinical trials have shown an overall survival (OS) benefit in the alternative treatment arm (Checkmate 214 (C), Keynote 426 (K)). The Javelin 101(J) trial has yet to show a significant improvement. Methods: A cross-study comparison of OS for the sunitinib arms of C, K and J was carried out. Special focus was given to risk group stratification and subsequent therapies. Data from the SUN pivotal trial (SP) was also taken into account. Results: Across the C, K and SP trials, OS was similar at approximately 78%. Despite a lower percentage of favourable risk patients compared to K and SP, an OS of 82% was observed in J. At 18 months, OS survival curves split ranging from 65% ©, 72.1% (K) to 76% (J). OS in the SUN arm in J at 18 months was comparable to OS of Nivolumab/Ipilimumab in C (78%). The rate of subsequent therapies ranged from 34.3% (K), 39.2% (J) to 54% (C) in the SUN arms. At the time of the SP trial almost no subsequent therapy options existed. In the experimental arms, the rate of subsequent therapies was 51.8% ©, 20.5% (K) and 20.8% (J). The existing data give no clear evidence of a correlation between subsequent therapies and OS. However, an analysis of the subsequent therapies/patients discontinuing therapy ratio (ST/DIS) and type of subsequent therapy (PD1/L1 directed or therapy with proven OS benefit (pOS) in randomized trials) in the SUN arms may be more conclusive (see table). The rate of subsequent therapies (ST/DIS) as well as PD(L)1 or pOS therapies were highest in J, followed by K and C. Conclusions: Despite the difficulties of a cross trial comparison, this data should raise awareness of the influence of a more intense subsequent therapy. It points to the necessity to standardize subsequent therapies in 1st line trials if OS is a primary study aim. Given this analysis, it may be pertinent to ask if an optimal or near optimal subsequent therapy following SUN might be equal to a 1st line IO/IO therapy with regards to OS.[Table: see text]