Survival outcomes and symptomatic central nervous system (CNS) metastasis in EGFR-mutant advanced non-small cell lung cancer without baseline CNS metastasis: Osimertinib vs. first-generation EGFR tyrosine kinase inhibitors.

Objectives: Central nervous system (CNS) metastases are common complications in epidermal growth factor receptor (EGFR) mutant non-small-cell lung cancer (NSCLC) treated with EGFR-tyrosine kinase inhibitors (TKIs). However, for patients without baseline CNS metastasis, data regarding the incidence of symptomatic CNS metastasis with EGFR-TKI treatment and its risk factors are still rare.

Materials And Methods: Patients with EGFR-mutant advanced NSCLC without baseline CNS metastasis who are receiving first- and/or third-generation EGFR-TKIs were included. Overall survival (OS), cumulative incidence of symptomatic CNS metastasis upon treatment failure, and their risk factors were evaluated.

Results: There were 813 patients enrolled, with 562, 106, and 32 received first-line gefitinib, erlotinib, and osimertinib, respectively, while 113 received second-line osimertinib. At a median follow-up of 18.1 months, the median OS was 45.5 months. There were 38 patients developed symptomatic CNS metastases. Osimertinib-treated patients tended to have a lower risk of CNS metastases compared with those treated with first-generation EGFR-TKIs (p = 0.059). However, the cumulative incidence curves of symptomatic CNS metastasis tended to reach a plateau after approximately 3 years regardless of which generation was used, and incidences beyond that period were similar in the two groups. Patients with L858R mutation exhibited a higher risk of developing CNS metastasis than patients with 19del mutation (p = 0.001). Interestingly, the presence of baseline neuroimaging was not associated with the risk of developing CNS metastasis or OS.

Conclusion: Compared with first-generation EGFR-TKIs, osimertinib can delay but not prevent the development of symptomatic CNS metastasis. L858R mutation is an independent risk factor for CNS metastasis.