IO-IO vs IO-TKI efficacy in metastatic kidney cancer patients: A structured systematic review over time

Multiple systemic immune-oncology (IO) combination therapies have demonstrated overall survival (OS) benefits in metastatic renal clear cell carcinoma (mRCC). However, the magnitude of benefits over time has not been compared in a structured fashion. To assess OS and progression free survival (PFS) efficacy as reflected by hazard ratios [HR]) according to the duration of follow-up over time for each of four IO combination therapies. A systematic PubMed (MEDLINE) literature review was performed (January, 1, 2016 to February, 20, 2022). Only phase III randomized clinical trials with proven OS benefit relative to sunitinib were included. These search criteria yielded four eligible RCTs: CheckMate 214 (nivolumab plus ipilimumab), Keynote 426 (pembrolizumab plus axitinib), CheckMate 9ER (nivolumab plus cabozantinib), CLEAR (lenvatinib plus pembrolizumab). OS and PFS HRs were tabulated for all four studies including all reported timepoints. Median follow-up ranged from 25-68 months for CheckMate 214 (5 timepoints), 13-43 months for Keynote 426 (3 timepoints), 18-33 months for CheckMate 9ER (3 timepoints) and 27-34 months for CLEAR (2 timepoints). Respective OS and PFS HRs were 0.68-0.72 and 0.98-0.86, 0.53-0.73 and 0.69-0.68, 0.60-0.70 and 0.51-0.56, 0.66-0.72 and 0.39-0.47 for CheckMate 214, Keynote 426, CheckMate 9ER and CLEAR. Regarding OS HRs virtually no change was recorded over time for CheckMate 214, but a decrease in magnitude occurred in the three IO-TKI remaining studies. Regarding PFS HRs, no benefit was recorded for CheckMate 214. Statistically significant benefit was recorded in the remaining IO-TKI studies. However, it also decreased with longer follow-up. It remains to be seen, whether further 'slippage' of efficacy will persist as the data matures further for all IO-TKI combinations.