Background: Osimertinib exhibits good efficacy in patients with T790M-positive non-small cell lung cancer (NSCLC) and acquired resistance to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs). Compared with the clinical trials, in real-world clinical practice, osimertinib must be administered to older patients and those with poor Eastern Cooperative Oncology Group performance status (ECOG-PS). Therefore, we investigated the association between osimertinib efficacy/safety and PS score, age, and other clinical features in patients with T790M-positive NSCLC.
Methods: We reviewed all patients with T790M-positive NSCLC and acquired resistance to initial EGFR-TKIs who were administered osimertinib between March 2016 and January 2018 at the Tokyo Metropolitan Cancer and Infectious Diseases Center in Komagome Hospital, Japan.
Results: In total, 31 patients, including 8 young (<65 years) and 23 elderly (≥65 years) patients, were included in the study. Of these, 10 (32.3%) patients had poor PS scores. The progression-free survival (PFS) was significantly shorter in young patients was than elderly patients [3.5 vs. 6.4 months, P=0.041; hazard ratio (HR), 2.41]. The overall survival (OS) of the young patients tended to be shorter than that of the elderly patients (5.3 vs. 19.4 months, P=0.067; HR, 2.58). The PFS (9.1 vs. 5.5 months; P=0.071; HR, 0.38) and the OS (not reached vs. 6.6 months, P=0.061; HR, 0.39) were shorter in patients with poor ECOG-PS than those with good ECOG-PS. The toxic effects of osimertinib were manageable. By multivariate analysis, both age and ECOG-PS were independent predictors of osimertinib efficacy.
Conclusions: Poor ECOG-PS and younger age were associated with lower efficacy of osimertinib in T790M-positive NSCLC.
Keywords: EGFR-TKI; Lung cancer; Threonine790Methionine; epidermal growth factor receptor (EGFR); osimertinib.