FLAIR: A Phase II, Open Label, Randomized Study of Osimertinib Plus Bevacizumab Versus Osimertinib in Recurrent or Metastatic Treatment-Naïve NSCLC Patients Harboring EGFR 21L858R Mutation.

Introduction: Osimertinib, the 3rd generation EGFR-TKI, has emerged as standard first-line treatment for patients with advanced EGFR mutated nonsmall cell lung cancer (NSCLC). Patients with exon 21 L858R mutation showed lower efficacy with EGFR-TKIs than those with 19Del mutation, even with osimertinib, it remains an unmet medical need to further improve the efficacy in L858R population. We present the rationale and design for FLAIR (NCT04988607), which will investigate the efficacy and safety of osimertinib plus bevacizumab versus osimertinib monotherapy in treatment-naïve recurrent or metastatic NSCLC patients harboring EGFR exon 21 L858R mutation.

Materials and methods: FLAIR is a prospective, multicenter, randomized, open label study, which is initiated by Chinese Thoracic Oncology Group (CTONG2002). Patients age ≥18 years with primary recurrent or metastatic nonsquamous NSCLC who are treatment-naïve with documented EGFR exon 21 L858R mutation is eligible. Patients will be randomized 1:1 to receive osimertinib 80 mg once daily plus bevacizumab 15mg/kg every 3 weeks or osimertinib monotherapy 80 mg once daily until progression or another discontinuation criterion is met. The primary endpoint is investigator-assessed progression free survival (PFS). Secondary endpoints include: overall survival rate at 24 months, time to treatment failure (TTF), overall response rate (ORR), disease control rate (DCR), duration of response (DoR), central nervous system (CNS) PFS, CNS ORR and safety.

Results: FLAIR has completed the enrollment, and results are expected in the fourth quarter of 2025 (depending on the actual event rate).

Conclusions: This study will offer better perspectives on the efficacy and safety of osimertinib plus bevacizumab combination therapy in treatment-naïve recurrent or metastatic NSCLC patients harboring EGFR exon 21 L858R mutation, providing valuable guidance for clinical practice.