An FDA-pooled analysis of frontline combination treatment benefits by risk groups in metastatic renal cell carcinoma (mRCC)

4559 Background: The International Metastatic RCC Database Consortium (IMDC) risk model was developed for prognosis of patients with mRCC treated with vascular endothelial growth factor (VEGF)-targeted monotherapy in the first-line setting. Efficacy in trials of anti-VEGF therapy has been generally consistent across risk groups, including for overall survival (OS). For trials of immunotherapy combinations, the small numbers of OS events for the favorable risk group in each trial limited reliable conclusions; however, there was a suggestion of possible differential effects on OS between favorable risk and other risk groups. Methods: We pooled individual patient data (n=3447) from four phase III randomized trials of combinations of immunotherapy + immunotherapy (n=1) or immunotherapy + anti-VEGF therapy (n=3) submitted to the US Food and Drug Administration in support of marketing applications. All trials calculated IMDC risk group for each patient and used a control arm of sunitinib. We combined intermediate and poor prognostic groups (“intermediate/poor”) and compared their OS to that of the favorable risk group using Kaplan-Meier and Cox Proportional Hazards methods. Results: In this pooled analysis, treatment with combination immune checkpoint therapy did not demonstrate an improvement in OS compared to sunitinib in the favorable risk group (HR 0.953; 95% CI: 0.72, 1.27). An improvement in OS was observed in the intermediate/poor risk group (HR 0.696; 95% CI: 0.62, 0.78). Conclusions: Our analysis of OS in patients treated with immunotherapy combinations compared to sunitinib suggests possible differential benefit in the favorable risk compared to the intermediate/poor risk group. These results are not conclusive and considered exploratory due to the relative immaturity of OS in the favorable risk group. Follow-up for survival continues in each study to allow for more definitive results.[Table: see text]