Lower starting dose of afatinib for the treatment of metastatic lung adenocarcinoma harboring exon 21 and exon 19 mutations

BackgroundAfatinib has shown favorable response rates (RRs) and longer progression free survival (PFS) in lung cancer patients harboring EGFR mutations compared with standard platinum-based chemotherapy. However, serious adverse drug reactions (ADRs) limit the clinical application of afatinib.MethodsWe designed a retrospective study, enrolling all patients with metastatic lung adenocarcinoma who were diagnosed and treated with 30 or 40mg daily afatinib as their initial treatment in three Kaohsiung Medical University-affiliated hospitals in Taiwan.ResultsA total of 179 patients were enrolled in the study, of which 102 (57%) and 77 (43%) received 30mg and 40mg afatinib daily as their initial treatment, respectively. The patients initially using 30mg afatinib daily had a similar RR (75% vs. 83%, p =0.1672), median PFS (14.5 vs. 14.8months, log-rank p =0.4649), and median OS (34.0 vs. 25.2months, log-rank p =0.5982) compared with those initially using 40mg afatinib daily. Patients initially receiving 30mg afatinib daily had fewer ADRs compared with those using 40mg daily. The overall incidence of moderate and severe ADRs was significantly lower in patients receiving 30mg afatinib daily compared with those using 40mg daily (49% vs. 77%, p=0.002); similar findings was observed in terms of severe ADRs (7% vs. 24%, p<0.0001).ConclusionPatients receiving 30mg afatinib daily as their initial treatment had similar RR, PFS, OS, but significantly fewer serious ADRs, as compared with those using 40mg as their starting dose.