Introduction: Osimertinib is a third-generation, irreversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that has demonstrated efficacy in the treatment of EGFR-mutant non-small-cell lung cancer (NSCLC) in prospective clinical trials.
Material and methods: This retrospective analysis evaluated the outcomes of 32 pretreated patients with EGFR T790M mutation who received osimertinib in clinical practice at seven centers in Poland within the Expanded Drug Access Program. Osimertinib was used in the second line in 59% of patients and in later lines in 41%.
Results: Objective response was attained in 16 patients (50%), and 12 subjects (38%) had stable disease. Median progression -free survival was 11.3 months in the overall population, 12.6 months in patients with EGFR exon 19 mutation and 7.5 months in patients with EGFR exon 21 mutation (p = 0.045). Median overall survival (OS) was 18.3 months. Overall, 58.4% and 45.6% of patients remained in follow-up after 12 and 24 months, respectively. Median OS appeared longer for patients without cerebral metastases than for those with cerebral metastases (27.4 vs 9.4 months, respectively; p = 0.078), and for patients with the Eastern Cooperative Oncology Group performance status (ECOG PS) 0-1 than those with ECOG PS 2 (27.4 vs 11.8 months, respectively; p = 0.189), although neither result reached statistical significance. Median OS of patients with partial response, stable disease and progressive disease was 27.4, 12.7 and 4.5 months, respectively (p < 0.001). Age, comorbidities, line of treatment with osimertinib, and type of activating EGFR mutation did not impact on OS. Adverse events of any grade or grade 3/4 were reported in 38% and 9% of patients, respectively. One person discontinued due to interstitial pneumonia.
Conclusion: These results confirm the value of osimertinib in patients with previously treated EGFR T790M-mutant NSCLC. Clinical benefit was evident in patients with cerebral metastases and moderate performance status.
Keywords: T790M mutation; clinical practice; epidermal growth factor receptor tyrosine kinase inhibitor; non-small-cell lung cancer; osimertinib.