Related Experiment Video
Updated: Aug 5, 2026
Profiling Sensitivity to Targeted Therapies in EGFR-Mutant NSCLC Patient-Derived Organoids
Published on: November 22, 2021
Impact of Genomic Subtype on Intracranial Outcomes in Treatment-naive EGFR mutant NSCLC with Osimertinib (IGnITE)
Emily Miao1, Emily Wo2, Lillian Boe3
1Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY; Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA.
Introduction:
Brain metastases (BM) causes significant morbidity and mortality in epidermal growth factor (EGFR) mutated non-small cell lung cancer (NSCLC). The effect of EGFR alteration subtypes on CNS-specific outcomes is poorly defined.
Methods:
Patients with EGFR-mutated NSCLC and BM treated with firstline osimertinib with or without SRS were retrospectively identified from 11 institutions. The primary endpoint was time to CNS progression. Time-to-event outcomes were analyzed using Kaplan-Meier methods. Hazard ratios were estimated with Cox proportional hazards models. Fine Gray models were used for competing risk endpoints.
Results:
Between 2016 and 2024, 470 patients were identified with the following alterations: exon 19 deletion (57%), L858R (33%), and atypical mutations (9.6%). At 24 months, cumulative incidence of CNS progression was 30% (95% CI: 25%-36%) for exon 19 deletions, 47% (95% CI: 39%-55%) for L858R, and 76% (95% CI: 59%-87%) for atypical mutations (p<0.001). In multivariable models, CNS progression was higher among patients with atypical alterations (HR 4.33, 95% CI: 2.72-6.91) and L858R mutations (HR 1.68, 95% CI: 1.27-2.23) compared with exon 19 deletions. Stratified outcomes for exon 19, L858R, and atypical mutations were similar across local and distant CNS progression, and neurological mortality. Upfront SRS was associated with improved CNS outcomes, with greatest benefit in patients with atypical alterations.
Conclusion:
Patients with atypical and L858R EGFR mutations had significantly worse CNS outcomes compared to those with exon 19 deletions. Upfront SRS reduced the risk of CNS progression, with the greatest benefit in patients with atypical alterations. EGFR subtype may help identify patients who benefit from SRS.
Insights
Patients with atypical and L858R epidermal growth factor receptor (EGFR) mutations face worse brain metastasis outcomes in non-small cell lung cancer. Upfront stereotactic radiosurgery (SRS) improves outcomes, especially for atypical EGFR mutations.
Area of Science:
- Oncology
- Neurology
- Genetics
Background:
- Brain metastases (BM) are a significant cause of mortality in EGFR-mutated non-small cell lung cancer (NSCLC).
- The impact of specific EGFR alteration subtypes on central nervous system (CNS) outcomes remains unclear.
- Understanding these differences is crucial for optimizing treatment strategies.
Purpose of the Study:
- To investigate the association between EGFR alteration subtypes and CNS progression in NSCLC patients with BM.
- To evaluate the efficacy of upfront stereotactic radiosurgery (SRS) in mitigating CNS progression based on EGFR mutation type.
- To identify patient subgroups who may benefit most from SRS.
Main Methods:
- Retrospective analysis of 470 patients with EGFR-mutated NSCLC and BM treated with first-line osimertinib.
- Inclusion of patients who received SRS with or without osimertinib.
- Primary endpoint: time to CNS progression. Secondary analysis using Kaplan-Meier, Cox proportional hazards, and Fine Gray models.
Main Results:
- Atypical EGFR mutations (9.6%) and L858R mutations (33%) were associated with significantly higher cumulative incidence of CNS progression compared to exon 19 deletions (57%) at 24 months.
- Multivariable analysis revealed higher CNS progression risk for atypical (HR 4.33) and L858R (HR 1.68) mutations versus exon 19 deletions.
- Upfront SRS demonstrated improved CNS outcomes, with the most substantial benefit observed in patients with atypical EGFR alterations.
Conclusions:
- EGFR mutation subtypes significantly influence CNS outcomes in NSCLC patients with BM.
- Atypical and L858R mutations portend worse CNS prognoses compared to exon 19 deletions.
- Upfront SRS is a valuable intervention for reducing CNS progression risk, particularly in patients with atypical EGFR alterations, suggesting its role in personalized treatment selection.
