Preventing Symptomatic Central Nervous System Metastasis in EGFR-Mutant Advanced Non-Small Cell Lung Cancer: Comparison of First- and Third-Generation EGFR Tyrosine Kinase Inhibitors

Abstract

Epidermal growth factor receptor (EGFR)-Tyrosine kinase inhibitors (TKIs) are standard treatment for EGFR-mutant advanced non-small cell lung cancer (NSCLC). Central nervous system (CNS) metastases, including brain parenchymal metastasis (BM) and leptomeningeal metastasis (LM), are common in the EGFR-TKI treatment failure. The different generation EGFR-TKIs have variant potencies of penetrating into the blood-brain-barrier. This study aims to compare the efficacy of first- and third-generation EGFR-TKIs in preventing symptomatic CNS metastases and to identify their risk factors. Patients with EGFR-mutant advanced NSCLC without baseline CNS metastasis and receiving EGFR-TKI treatment were selected. The cumulative incidence of symptomatic CNS metastasis upon treatment failure, and overall survival (OS) of patients who developed CNS metastasis, were measured from the initiation of EGFR-TKIs, using the Kaplan-Meier method. The risk factors for CNS metastasis, and predictors of OS were identified using Cox proportional hazard regression. 935 patients from two academic medical centers were enrolled, with 633, 143 and 35 receiving first-line gefitinib, erlotinib and osimertinib, respectively, the remain 124 patients received osimertinib for acquired T790M mutation. On baseline, 19del, L858R and uncommon mutations were detected in 427, 386 and 122 patients, respectively. At the median follow-up of 10 months, treatment failure was observed in 517 patients, of whom 45 developed symptomatic CNS metastasis, with 37 developing BM, 4 LM, and 4 with both BM and LM. The 1-year, 2-year and 3-year cumulative rate of symptomatic CNS metastasis, were 4.2%, 7.9% and 14.4%, respectively. There was no significant difference in symptomatic CNS metastasis among patients receiving gefitinib or erlotinib, while osimertinib treatment was found to have a lower rate compared to first-generation TKIs (HR 0.45; 95%CI 0.20-0.99, p = 0.049). However, cumulative rate of symptomatic CNS metastasis at 3-year in osimertinib group reached the similar level as the first-generation TKIs. Of interest, the curves of CNS metastasis tend to reached a plateau after three years no matter which generation was used. Patients harboring L858R mutation were at a higher risk of developing CNS metastasis, than other mutations (p = 0.003). Among the 45 patients with CNS metastasis, median OS was 22 months, and patients with single cranial lesion had a significant longer OS (p = 0.011). Compared with first-generation EGFR TKIs, osimertinib significantly delays the development of symptomatic CNS metastasis in the EGFR-mutant advanced NSCLC without baseline CNS metastasis. L858R mutation is a risk factor for CNS failure during EGFR-TKIs treatment.