A Plea for Optimizing Selection in Current Adjuvant Immunotherapy Trials for High-risk Nonmetastatic Renal Cell Carcinoma According to Expected Cancer-specific Mortality

Background: Tyrosine kinase inhibitor-based adjuvant therapy showed no survival benefits for patients with high-risk nonmetastatic renal cell carcinoma (nmRCC). Five randomized immune-oncology checkpoint inhibitor trials are ongoing. We assessed the effect of stage, grade, and histologic type on cancer-specific mortality (CSM) in candidates for 1 of the 4 North American ongoing immune-oncology checkpoint inhibitor trials of high-risk nmRCC. Patients and Methods: From the Surveillance, Epidemiology, and End Results database (2001-2015), we identified patients who had undergone surgery for nmRCC and had met the inclusion criteria for the PROSPER RCC (nivolumab in treating patients with localized kidney cancer undergoing nephrectomy), CheckMate 914 (a study comparing the combination of nivolumab and ipilimumab versus placebo in participants with localized renal cell carcinoma), KEYNOTE-564 [safety and efficacy study of pembrolizumab (MK-3475) as monotherapy in the adjuvant treatment of renal cell carcinoma post nephrectomy], or IMmotion010 [a study of atezolizumab as adjuvant therapy in participants with renal cell carcinoma (RCC) at high risk of developing metastasis following nephrectomy] trials. Kaplan-Meier and multivariable Cox regression models were used to assess the 10-year CSM rates in the overall cohort according to stage, grade, and histologic characteristics, and in 4 generated random samples according to the eligible patients for each of the 4 trials. Results: Of 116,750 patients who had undergone surgery for nmRCC, 18,559 (15.9%) had fulfilled the inclusion criteria for 1 of the 4 trials. The greatest proportion of higher stage and grade combinations and sarcomatoid histologic features would have qualified for IMmotion010, followed by KEYNOTE-564, CheckMate 914, and PROSPER RCC. Multivariable Cox regression models demonstrated the most unfavorable prognosis for stage N1 grade 3/4 (hazard ratio [HR], 11.5; P <.001), stage T4N0 grade 3/4 (HR, 9.8; P <.001), and sarcomatoid histologic features (HR, 5.5; P <.001). Among the 4 random samples, the difference in the qualifying criteria resulted in the greatest versus progressively lower CSM rates in the IMmotion010, KEYNOTE-564, CheckMate 914, and PROSPER RCC trials, respectively (P <.001). Conclusions: Our findings indicate that participation in adjuvant immunotherapy trials should be predominantly encouraged for patients with high-grade stage T3, T4, and N1 and patients with any stage with sarcomatoid pathologic features.