491P - Clinical outcomes of leptomeningeal metastases in EGFR-mutant lung adenocarcinoma

Background

Leptomeningeal metastases (LM) remain challenging for patients with non-small cell lung cancer. EGFR mutation shows a higher incidence rate of LM with poor prognosis. 3^rd generation TKI has better cerebral-spinal fluid(CSF) penetration and may be a promising treatment. Here we collected LM clinical features and outcome in EGFR-mutant lung adenocarcinoma in high EGFR mutation prevalence area.

Methods

This is a retrospective observational cohort study, conducted in a tertiary medical center in Taiwan. Patients with newly diagnosed advanced lung adenocarcinoma with common EGFR mutation were enrolled. LM were diagnosed by brain imaging study or cytology study of CSF analysis. Patients without initial brain MRI imaging or patients who underwent CNS surgery initially were excluded. All the data is valid up to Dec 31, 2017.

Results

From 2013 to 2015, a total of 283 patients was included. All patients were treated with first-line TKIs as systemic treatment initially. Thirty-four patients had LM, accounting for 12.0% (34/283) of this cohort. Only four patients in the LM group (11.7%) received CSF study, and three of them showed malignant cells in their CSF. Patients with LM had median overall survival(OS) 26.2 months, whereas patients with brain tumor progression had median OS 42.3 months. (p = 0.002) For patients with LM, the median OS after LM is 5.1 months. Patients with younger age(HR0.63[0.45-0.90], p = 0.01) and initial M1b(HR 2.86[1.81-4.53], p < 0.001) were associated with higher risk or intracranial progression. Among 34 patients, 6 patients received 3^rd generation TKI and revealed significant better OS than those without 3^rd TKI. (OS 15.3 months vs 3.7 months, p = 0.03).

Conclusions

LM show poor prognosis for patients with EGFR-mutant lung adenocarcinoma, compared with other types of brain metastases. Younger age and initial M1b associated with higher risk. Patients with 3^rd generation TKI may bring benefit to these patients.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Taipei Veterans General Hospital.

Disclosure

C-H. Chiu: Honoraria (self): AstraZeneca; Honoraria (self): Boehringer Ingelheim; Honoraria (self): Roche. All other authors have declared no conflicts of interest.