ESTRO 2024 - Abstract Book

S1664

Clinical - Lung

ESTRO 2024

Epidermal growth factor receptor mutation (EGFR+) and expression programmed death-ligand 1 (PD-L1+) in NSCLC have been associated with improved patient survival outcomes considering advancements in targeted therapy and check point inhibitors. However, the impact of EGFR mutation (EGFR+) and expression of PD-L1 in brain metastasis has not been well studied. This project investigates clinical impact of EGFR and PD-L1 on brain metastasis patient outcomes following stereotactic radiosurgery (SRS) treatment.

Material/Methods:

88 patients with 229 total brain metastases who were treated with SRS were included in this IRB approval retrospective study. Seventy-one patients were evaluated for PD-L1 expression and 13 were positive (PD-L1 > 1%), while 73 patients were evaluated for EGFR and 17 were positive. Two patients were positive for both PDL1 and EGFR mutation. EGFR and PD-L1 statuses were evaluated for correlation with clinical outcomes, including median survival, overall survival (OS), intracranial recurrence and radiation necrosis. Radiation necrosis was defined as symptomatic necrosis requiring steroid treatment. Survival curves were calculated via Kaplan Meier curves. P values <0.05 were considered significant.

Results:

Median follow-up after SRS was 9.6 months. Median survival was 31months for entire group of patients. Median survival for PD-L1+ and EGFR+ patients were undefined and 31 months, respectively. Total local recurrent rate after SRS was 4% (8/225of targets). EGFR+ was associated with decreased risk of intracranial recurrence (31% vs 55%; p=0.03), and PD-L1+ trended for decreased intracranial recurrence (39% vs 55%). Both PD-L1+ and EGFR + were individually associated with increased radiation necrosis following SRS (p<0.0001 and 0.002, respectively). The rates of radiation necrosis were 5.4% and 7.9% for EGFR- and PD-L1- patients, and 24% for EGFR + and 38% for PD-L1+, respectively. EGFR+ and PD-L1+ status was individually associated with increased median time to develop necrosis on Kaplan Meier analysis (p=0.03 and p=0.02, respectively). Patients who had longer OS tended to have increased risk of radiation necrosis (p=0.01).

Conclusion:

PD-L1 expression and EGRF mutation patients treated with immunotherapy and target therapy reduced intracranial recurrence and increased SRS associated intracranial necrosis. The significant survival benefit of PD-L1 expression and EGFR mutation was not clearly seen in this study. The limitation of this study being respective, small number of the patients and incomplete data collection may result in the information inconsistence with literatures.

Keywords: NSCLC, Brain metastasis, Target and Immunotherapy.

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