Objective: Immune checkpoint inhibitor (ICI) efficacy in the treatment of metastatic renal cell carcinoma (RCC) without brain metastases (BMs) is well established in several clinical trials; however, patients with BMs were typically excluded from these trials. Therefore, the efficacy of ICI in the treatment or prevention of BM remains unclear. The primary aim of the study was to address the efficacy of ICI in treatment of patients with RCC BMs compared with patients receiving targeted therapies. A secondary aim was to evaluate the risk of RCC BM development among patients who received ICI versus targeted therapies early in their treatment course.
Methods: A retrospective single-center review between 2011 and 2018 identified 425 patients treated for metastatic RCC. The study group included patients who received ICI and/or targeted therapies during their disease. Data analyzed included demographic information, systemic treatments, overall survival from RCC diagnosis (OSRCC) and from BM diagnosis (OSBM), and BM development. Fisher's exact test was used to evaluate the frequency of BM occurrence. Survival was assessed using Kaplan-Meier curves and log-rank tests.
Results: Of the 425 patients, 125 received ICI and 300 were treated with molecular targeted agents only during their clinical course. BMs occurred in 113 (9.5%) of the 425 patients. Among patients with BMs, OSRCC was improved with the use of ICI (77.2 vs 25.2 months, p < 0.001), with 1-, 2-, and 5-year survival rates of 93.9%, 81.8%, and 62.6%, respectively. The use of ICI was associated with increased OSBM (21.7 vs 8.9 months, p = 0.001). The rate of BM development was lower when patients were treated with ICI (8/100 [8.0%]) compared with targeted therapy (47/267 [17.6%]) (OR 0.41, 95% CI 0.18-0.89; p = 0.021).
Conclusions: ICI was associated with improved OSRCC and OSBM in patients with BMs and decreased the probability of BM development in patients with metastatic RCC. Prospective trials are needed to further evaluate optimal use of ICI in treatment of RCC BMs.
Keywords: brain metastasis; checkpoint inhibitor; molecular targeted therapy; renal cell carcinoma.