EGFR Exon 20 Insertion Mutations: Clinicopathological Characteristics and Treatment Outcomes in Advanced Non-Small...

Area of Science:

• Oncology
• Genetics
• Pharmacology

Background:

• Epidermal growth factor receptor (EGFR) gene exon 20 insertion (ex20-ins) mutations define a rare, heterogeneous subset of non-small cell lung cancers (NSCLCs).
• These mutations confer resistance to established EGFR tyrosine kinase inhibitors (TKIs).
• Limited data exists on the clinical characteristics and treatment outcomes for patients with EGFR ex20-ins.

Purpose of the Study:

• To characterize the clinical features and treatment outcomes of patients with EGFR exon 20 mutations (ex20-mut) using a multinational patient database.
• To compare the efficacy of different systemic treatments, including chemotherapy, TKIs, and immune checkpoint inhibitors, in this patient population.

Main Methods:

• Retrospective review of patients with EGFR exon 20 mutations (excluding T790M) from six Australian institutions.
• Collection and statistical analysis of clinical characteristics and outcomes with various systemic treatments.

Main Results:

• Among 109 patients with ex20-mut, 61% were female and 75% Caucasian. Metastatic disease was common, particularly to the central nervous system (48%) and liver (24%).
• Platinum-based chemotherapy (PBC) yielded a 43% objective response rate (ORR), 6.9-month median progression-free survival (mPFS), and 31.0-month median overall survival (mOS).
• Conventional TKIs showed limited efficacy (13% ORR, 3.4-month mPFS), while immune checkpoint inhibitor monotherapy (ICIm) was ineffective (4% ORR, 2.6-month mPFS). Notably, S768I mutations showed moderate TKI activity (50% ORR, 18.2-month mPFS).

Conclusions:

• Patients with EGFR ex20-mut NSCLC exhibit poorer survival compared to those with common EGFR mutations, likely due to limited targeted therapy options.
• Platinum-based chemotherapy is a more effective treatment strategy than conventional EGFR TKIs for EGFR ex20-ins.
• While conventional TKIs are largely ineffective, specific mutations like S768I may retain sensitivity, warranting further investigation. Immune checkpoint inhibitors demonstrated no significant benefit as monotherapy.