Afatinib is a second-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI). Compared to cytotoxic chemotherapy, afatinib has been shown to have better efficacy in the treatment of non-small cell lung cancer harboring EGFR mutations. However, 40 mg daily as the initial dose is often accompanied by serious adverse drug reactions (ADRs) and 28 to 53.3% of patients required a dose reduction. No previous study has compared the clinical efficacy and ADRs of different initial doses (40 mg vs. 30 mg daily) of afatinib in lung cancer treatment. Patients with stage IV lung adenocarcinoma diagnosed and treated in two Kaohsiung Medical University-affiliated hospitals in Taiwan between May 2014 and August 2016 were identified and followed until December 2016. Demographic characteristics, responses, progression-free survival (PFS), overall survival (OS), and ADRs were recorded. A total of 48 patients with stage IV lung adenocarcinoma harboring susceptible EGFR mutations who received afatinib as their first-line therapy were enrolled. Patients using 30 mg daily as the initial dose tended to be older and female and have a smaller body size. The patients using 30 mg of afatinib daily as their initial dose had a similar response rate to those receiving 40 mg daily (76% vs. 95%, p = 0.0862) and the same disease control rate (100% vs. 100%, p = 0.1486). The PFS was similar between the patients receiving 30 mg or 40 mg of afatinib daily (median PFS: 469 vs. 443 days, log-rank p = 0.8418). Patients receiving 30 mg daily had a significantly lower incidence of diarrhea than those using 40 mg daily (41% vs. 100%, p < 0.0001). An initial afatinib dose of 30 mg daily had similar response and progression-free survival rates as an initial dose of 40 mg daily, but resulted in fewer serious ADRs in this study.

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) such as gefitinib can provide better efficacy and prolonged progression free survival (PFS) than cytotoxic chemotherapy for metastatic lung non-squamous cell carcinoma harboring susceptible EGFR mutations when used as first-line therapy. Cytotoxic chemotherapy is regarded as being the standard therapy to overcome acquired resistance to an initial EGFR TKI. However, there is currently no consensus on how best to treat patients who develop resistance to both an initial EGFR TKI and chemotherapy. We enrolled stage IV lung adenocarcinoma patients with an EGFR mutation and who had developed acquired resistance to gefitinib and cytotoxic chemotherapy from two university-affiliated hospitals in Taiwan from June 2011 to December 2014. Basic demographic data, included Eastern Cooperative Oncology Group (ECOG) performance status were collected, and the response rate, progression-free survival (PFS) and overall survival (OS) were analyzed. Two hundred and nine patients with mutated EGFR and who took gefitinib as the first-line therapy were identified in the study period, of whom 86 received second-line cytotoxic chemotherapy, and 60 who received third-line therapy were eligible for this study. The patients who received cytotoxic chemotherapy had a significantly higher disease control rate than those who received erlotinib (73% vs. 46%, p = 0.0363), however there were no significant differences in PFS (2.9 months vs. 3.1 months, p = 0.9049) and OS (8.9 months vs. 7.9 months, p = 0.4956). Platinum- or pemetrexed-based chemotherapy provided similar PFS and OS as others did. The only significant poor prognostic factors for OS were old age (≥65 years) (HR = 5.97 [2.65–13.44], p < 0.0001) and poor performance status (ECOG ≥2) (HR = 5.84 [2.61–13.09], p < 0.0001). Retreatment with an EGFR TKI is not inferior to cytotoxic chemotherapy when used as salvage therapy for patients with adenocarcinoma with an EGFR mutation, especially if a third-generation EGFR TKI is not available, or if the reason for resistance is unknown or is not related to the T790M mutation. Old age and poor ECOG score were both poor prognostic factors in the salvage therapy.