[Survival analysis of different kinds of tyrosine kinase inhibitors in the treatment of patients with epidermal growth factor receptor mutated non-small cell lung cancer and leptomeningeal metastasis].

Objective: To explore the prognosis of patients with leptomeningeal metastasis (LM) and epidermal growth factor receptor mutated (EGFRm) non-small cell lung cancer (NSCLC) treated with different kinds of tyrosine kinase inhibitors (TKIs). Methods: From January 2016 to June 2021, the clinicopathological data of 70 patients confirmed by histologically or cytologically EGFRm LM who received different types of TKIs in Cancer Hospital of Chinese Academy of Medical Sciences were retrospectively analyzed. According to treatment patterns, patients were divided into the first-and second-generation EGFR-TKIs treatment group and the third-generation EGFR-TKIs treatment group [Osimertinib 80 mg once a day], and the prognosis and prognostic factors (with Cox proportional hazards model) of patients in different treatment group were assessed. The next-generation sequencing (NGS) of paired samples of cerebrospinal fluid (CSF) and plasma from 64 patients at the time of LM diagnosis was performed simultaneously. Results: There were 20 males and 50 females in 70 EGFRm NSCLC patients with LM. The age ranged from 35 to 69 years, with a median age of 56 years. A total of 24 patients received the first-and second-generation EGFR-TKIs treatment, and 46 received the third-generation EGFR-TKIs treatment. Twenty-four patients developed disease progression on the first-and second EGFR-TKIs treatments, followed by treatment with the third-generation EGFR-TKIs (Osimertinib) in 12 cases, chemotherapy or anti-angiogenesis therapy in 4 cases, and the optimal supportive treatment in 8 cases. Among the 70 patients, 18 had partial response (PR), 48 had stable disease (SD), and 4 had progressive disease (PD). The objective response rate (ORR) and disease control rate (DCR) were 26% (18/70) and 94% (66/70), respectively. The median follow-up time was 16.5 months. The median progression-free survival (PFS) was 5.3 months(95%CI: 2.8-7.8)in the first-and second-generation EGFR-TKIs and 10.8 months (95%CI: 7.9-13.6) in the third-generation EGFR-TKIs, and the difference was statistically significant (P=0.019). The median overall survival (OS) was 14.9 months (95%CI: 9.7-20.0) and 15.7 months (95%CI: 13.3-18.1) in the two groups, respectively, but no statistical differences was observed (P=0.713). Univariate analysis showed that the PFS of patients with EGFRm LM were related to gender and different types of EGFR-TKIs (P˂0.05). Multivariate analysis demonstrated that male (HR=2.30, 95%CI: 1.31-4.03, P=0.004) and the first-and second-generation EGFR-TKIs (HR=2.03, 95%CI: 1.20-3.41, P=0.008) were independent risk factors for PFS in patients with EGFRm LM. The EGFR mutation was detected in 61 (95%) CSF and in 27 (42%) plasma samples. Conclusion: In EGFRm NSCLC patients with LM, the dose of Osimertinib 80 mg (once a day) has a significant PFS benefit compared with the first-and second-generation EGFR-TKIs.