Immu-03. immune checkpoint inhibitors in small cell lung cancer patients developing brain metastases

Abstract INTRODUCTION Small cell lung cancer (SCLC) is known for rapid growth, and about 40-50% of SCLC patients will develop brain metastases (BM). The addition of immune checkpoint inhibitors (ICI) to the standard chemotherapy, which is the current backbone of first-line therapy, has resulted in more prolonged survival than chemotherapy alone in SCLC patients. PURPOSE This study aimed to assess the effect of ICI before BM development in SCLC patients on time to BM development and survival. METHODS A single-institutional retrospective review of SCLC patients that underwent cranial radiation therapy between January 2014 and June 2020 was performed to assess the impact of ICI therapy on time to BM development, overall survival (OS), and time to failure of BM treatment (defined as local or distant BM recurrence) using a multivariable Cox Proportional Hazards model. RESULTS Among 197 included patients, 23 patients (11.7%) received ICI before BM development. Extensive stage of SCLC at diagnosis was observed in eighteen patients (78.2%) in the ICI group and 133 (76.4%) in the non-ICI group. In total, seventeen patients (8.6%) received prophylactic cranial irradiation, of which seven patients (30.4%) also received ICI. ICI were associated with prolonged time to BM in comparison with the non-ICI group (HR = 0.29, 95% CI: 0.18-0.47). ICI were also associated with an increased OS (HR = 0.56, 95% CI: 0.32-0.97) and prolonged time to BM treatment failure (HR = 0.32, 95% CI: 0.15-0.71) in comparison with patients who did not receive ICI. CONCLUSION The use of ICI before BM development was associated with a longer time to BM. Additionally, ICI therapy was associated with an increased OS and prolonged BM treatment failure. These results are a proof of concept of the potential benefit of ICI therapy in SCLC patients, and the presented results should be further validated in larger cohorts.