Time-Dependent Comparative Effectiveness of First-Line Treatment for Metastatic Clear Cell Renal Cell Carcinoma: A Restricted Mean Survival Time-Based Network Meta-analysis.

[BACKGROUND] Given that immune checkpoint inhibitor-based regimens frequently yield delayed separation and late plateaus, conventional hazard ratio analyses that assume proportional hazards may misstate true benefit.

[OBJECTIVE] We aimed to test the validity of the proportional hazards assumption in first-line metastatic clear cell renal cell carcinoma trials and to compare the immune checkpoint inhibitor-based regimens using restricted mean survival time.

[METHODS] We performed a systematic review and network meta-analysis of phase III randomized controlled trials of first-line treatment for metastatic clear cell renal cell carcinoma, including immune checkpoint inhibitor-tyrosine kinase inhibitor combinations or dual-immune checkpoint inhibitor regimens. Individual patient data were reconstructed from the Kaplan-Meier curves of overall survival and progression-free survival. The restricted mean survival time differences were estimated.

[RESULTS] Five trials (4206 patients; six treatment arms) were examined. Proportional hazards assumption was violated in 60% of both overall survival and progression-free survival comparisons. In the restricted mean survival time-based network meta-analysis of overall survival, immune checkpoint inhibitor-tyrosine kinase inhibitor combinations, especially Nivolumab + Cabozantinib, dominated at 12-48 months, whereas Ipilimumab + Nivolumab ranked highest beyond 48 months. In the International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) favorable-risk subgroup, Avelumab + Axitinib showed a favorable long-term profile despite the lack of statistical significance. In IMDC intermediate/poor-risk, patterns mirrored the overall population. For progression-free survival, Pembrolizumab + Lenvatinib ranked best across IMDC subgroups. Limitations included the reliance on reconstructed data and heterogeneity across trials.

[CONCLUSIONS] Given the frequent proportional hazards violations, hazard ratio-only syntheses are insufficient for modern immune checkpoint inhibitor-based regimens. In the restricted mean survival time-based network meta-analysis, Pembrolizumab + Lenvatinib delivered rapid disease control, and Ipilimumab + Nivolumab showed the greatest late survival advantage in IMDC intermediate/poor-risk.

[PROSPERO REGISTRATION NUMBER] CRD420251143602.