P2.05-030 WBRT Prior EGFR TKIs is Effective Treatment Option for NSCLC Patients with CNS Metastases Harboring EGFR Mutation: Topic: Multimodality Treatment

Abstract

Central nervous system (CNS) metastases are considered as a common cause of morbidity and mortality in advanced non-small-cell lung cancer (NSCLC). It is estimated that 20–40% of NSCLC develop CNS metastases during their disease course. Sensitivity of chemotherapy is limited in CNS metastases of NSCLC, because of restrict transit function of blood-brain barrier. The main treatment options based on whole brain radiation therapy (WBRT), stereotactic radiosurgery, neurosurgery or combination of them. Median overall survival (mOS) achieved in NSCLC with CNS metastases treated with irradiation methods is 6.5-7.5 months. Introduction of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) – gefitinib, erlotinib, afatinib – improved the treatment possibilities in selected group of NSCLC patients harboring EGFR gene mutations. Also CNS metastatic lesions of NSCLC showed sensitivity to EGFR-TKIs (mOS to 15-17 months). Moreover, concurrent EGFR TKIs and WBRT may be used synergistic because potentially improve survival and delays intracranial progression. The main aim of the study was evaluation weather implementation of WBRT prior EGFR TKIs in NSCLC patients with CNS metastases might influence on their survival in comparison to patients without CNS metastases treated with EGFR TKIs monotherapy. The studied group included 178 NSCLC patients harboring EGFR gene mutation. 160 (110 female, 50 male; median age 67 years) patients with primary NSCLC received EGFR TKIs in first or second line of treatment. 18 patients (16 female, 2 male; median age 69 years), who had diagnosed CNS metastases, received WBRT prior administration of EGFR TKIs. The treatment response was showed in both studied group. We did not observe a significant difference in survival in both studied groups. The progression free survival (PFS) in patients with primary NSCLC treated with EGFR TKIs and in patients with CNS lesions treated with WBRT prior EGFR TKIs was 10 vs. 9 months (p=0.785; HR=1.07; 95% CI=0,618-1.866), respectively. Also mOS did not show significance discrepancies in both studied group (26 vs. 32 months, respectively; p=0.32; HR=0.639; 95% CI=0.301-1.356). Implementation of WBRT prior TKIs did not lead to additional neurotoxicity. The following study showed that combination of WBRT prior TKIs in NSCLC patients with CNS metastases achieves similar benefit like treatment of primary NSCLC (without CNS metastases) with EGFR TKIs monotherapy. Based on overall data, patients with CNS metastases achieved better response rate when EGFR TKIs are administrated prior WBRT. It may be caused by EGFR TKIs feature which possess CNS penetrability for radiation.