Update Phase II Results of Early Primary Tumor Stereotactic Body Radiotherapy Combined with First-Line EGFR-TKI in Advanced EGFR Mutated NSCLC

Abstract

Background: Our previous work (ChiCTR-OIN-17013920) has reported the efficacy and safety of early primary tumor stereotactic body radiotherapy (SBRT) combined with Icotinb in advanced EGFR mutated (EGFRm) NSCLC patients (2018 IASLC WCLC Abstract #11985). Hani Ai-halabi et al. reported that about 80% of EGFR TKI drug resistance was at the primary site. Here we report the updated results. Method: Patients with pathologically confirmed advanced NSCLC with 19/21 EGFRm were enrolled between September 2016 and March 2019. SBRT was performed during the first month of oral first-line EGFR-TKI (Icotinib 125mg three times daily or Gefitinib 250mg once daily) in patients who were assessed as partial response or stable disease according to RECISE v1.1 assessment. The primary tumor was given SBRT at dose of 50Gy/5F or 60Gy/8F for peripheral and central primary, respectively. The primary endpoints were progression free survival] (PFS) and pattern of failure, while the second endpoints were overall survival time (OS) and adverse events (AEs). Result: 36 patients were recruited in this study. The follow-up time was 14.5 months (range 3.4-30.4). Median age was 66 years (range 49-83). There were 20 males and 16 females. Eighteen patients with 19-del mutation and 18 had L858R mutation. Overall, median PFS and median OS was 14.1 months and 26.3 months (Figure 1), respectively. Three patients had progression at the primary site, 5 patients had mixed progression and 19 patients with distant progression only. In subgroup analysis, the median PFS was 14.1 months vs. 12.8 months in 19-del vs. L858R mutation patients. The median OS was 19.4 months in L858R mutation group while that in 19-del mutation was immature. Additionally, there was no ≥grade 3 AEs in patients treated with this regimen. Conclusion: This study suggested that early primary tumor SBRT may play a role to delay resistance of first-line EGFR-TKI in advanced EGFRm NSCLC patients. Patients with 19-del mutation may gain a better survival time compared with L858R mutation. The promising results are to be validated in a multi-center, comparable randomized phase III clinical trial (Target-SBRT, NCT03727867).