Safety of osimertinib in adult patients with metastatic epidermal growth factor receptor T790M mutation-positive non-small cell lung cancer: Results from a Phase IV study in India.

Background: A Phase IV, single-arm study was conducted to assess the safety of osimertinib in Indian patients with epidermal growth factor receptor (EGFR) T790M mutation-positive stage IV non-small cell lung cancer (NSCLC). Methods: Enrolled patients received 80 mg osimertinib for six cycles or until disease progression or unacceptable toxicity or withdrawal. Primary safety variables included treatment-emergent adverse events (TEAEs), serious adverse events (SAEs), and adverse events (AEs) leading to discontinuation/interruption/change (D/I/C) of drug dose, and AEs of special interest (AESIs). AEs were summarized by the percentage of patients experiencing at least one occurrence of each event. Results: Of the 60 enrolled patients (median age 58 [range: 34-81] years; 51.7% women) at eight sites, nine patients were discontinued prematurely due to disease progression (n = 7) and death (n = 2); median (range) duration of treatment was 126 (1-134) days. Median age of patients was 58 (34-81) years; 51.7% (n = 31) were women; 86.7% (n = 52) were nonsmokers; and most of them (98.3%) had adenocarcinoma. About 75% (n = 45) of patients experienced any of the TEAEs, with the most frequent being fatigue and creatine phosphokinase (CPK) increase (n = 6, 10% each). TEAEs in 11 (18.3%) patients were judged as study treatment related, with CPK increase being the most common (n = 4, 6.7%). TEAEs led to D/I/C of drug dose in eight (13.3%) patients, with one being study treatment related. Nine (15%) patients had AESIs of dyspnea (n = 6), chest pain (n = 2), and cardiorespiratory arrest (n = 1); two of them had a fatal outcome. One AESI (mild dyspnea) was considered study drug related. TEAEs of grade >= 3 were reported in seven (11.7%) patients, including dyspnea in two (3.3%), followed by diarrhea, mucosal inflammation, cardiorespiratory arrest, and others (n = 1, 1.7% each). None of the SAEs and fatal events were considered as study treatment related. Seven (11.7%) patients had abnormal electrocardiogram (ECG; not clinically significant) at the end of the study. Conclusion: Our study confirms the favorable safety profile of osimertinib without any new safety concerns in Indian patients with EGFR T790M mutation-positive stage IV NSCLC.