Real-world data analysis of clinical characteristics and survival outcomes in Russian patients with NSCLC harboring <i>EGFR</i> mutations.

Abstract

e20650 Background: EGFR -mutated ( EGFRm ) metastatic non-small cell lung cancer (mNSCLC) is a heterogeneous disease. This analysis aimed to explore clinical and morphological characteristics and survival outcomes in Russian patients with EGFRm mNSCLC. Methods: We conducted a single-institution retrospective analysis of patients with EGFRm mNSCLC who were treated with EGFR tyrosine kinase inhibitors (TKIs) between 2019 and 2024. Results: 104 patients (pts) were included in the study, with 71.84% female and 28.16% male. The median age of pts at the time of diagnosis was 63 (31 to 87) years. 66% of pts were never smokers. TTF1 expression was found in 95,8% of tissue samples. The most common mutations were EGFR ex19del (65.1%) and L858R (23.3%). EGFR ex20 mutations were observed in 3.88%. Initial EGFR co-mutations were detected in 6.8% and in 1% - rare EGFR mutation ( L861Q ). The predominant sites of metastasis (mts) were the lungs (35.2%), brain (32.8%), bones (28.9%), and pleura (28.1%). Metastases to the liver and adrenal glands occurred in 6.5% and 2.2% of patients, respectively. Prior to TKIs, 19.1% of pts received chemotherapy (CT), mainly due to the absence of data on EGFR status. Upon receiving EGFR status information, all pts who initially received CT were switched to TKIs before progression. As the first-line treatment, 85.7% of pts received TKIs. Gefitinib (G) was administered to 40.3% of pts, Erlotinib (E) - 5.2%, Afatinib (A) - 26.0%, Osimertinib (O) - 27.3%. 44.7% of patients had a confirmed objective response. The disease control rate was 94.7%. The most frequent sites of mts after progression on TKIs were lungs (34.2%), multiple sites (23.7%) and brain (18.4%), in 57.1% of them as new site of mts. Subsequent lines of treatment were administered to 72.2% of pts, with 35% receiving immunotherapy combined with CT and anti-VEGF agents (ICIs), while 37.5% received TKIs. T790M mutation testing was performed in 27.6% of pts (n=29) and detected in 44,8% (n=13). The median number of therapy lines for pts at the time of data analysis (18JAN2025) is 2 (1-4). Radiation therapy was administered to 25.71% of pts (n=27), with brain mts being the most common indication (66.7%, n=18), followed by bone mts (29.6%, n=8) and treatment of oligoprogression (3.7%, n=1). Median PFS for 1 st line was: CT – 6.0 (0.0, 12.4) mo, G – 12.1 (3.0, 21.2) mo, E - 9.0 (6.5, 11.4) mo, A – 10.03 (0.0, 31.1) mo, O – 25.03 (22.0, 39.0) mo. After progression on TKIs the mPFS for 2 nd line was: CT – 4.3 (2.4-6.1) mo, ICIs – 5.97 (1.9-10.1) mo. On the date of analysis the mOS was not reached. Conclusions: Our analysis shows that the disease progression in EGFRm mNSCLC varies widely depending on mutation type, treatment approach, and metastatic sites. 1 st line with TKIs was effective, with a high rate of disease control and objective response, though mPFS near 2 years and very short mPFS of subsequent lines.