2017 年 43 巻 3 号 p. 145-153
The absorption of gefitinib is dependent on gastric pH. However, an increase in gastric pH via the use of antacids such as proton pump inhibitors (PPI) and histamine H2 receptor antagonists may reduce the bioavailability and efficacy of gefitinib.
In this study, we report the influence of the concurrent use of antacids with gefitinib on the efficacy in epidermal growth factor receptor (EGFR) mutation-positive non-small cell lung cancer (NSCLC). Our subjects were 68 patients with NSCLC who were treated with gefitinib at our hospital between 2008 and 2015.
In the study, we compared time to treatment failure (TTF), overall survival (OS), response rate, disease control rate and adverse effect rates in patients receiving antacids in combination as well as (AC; n = 29) with those only receiving gefitinib (no AC; n = 34).
The patients in the AC group exhibited a significant difference in TTF (409 days (95％CI: 1.00-4.22) vs 901 days (95％CI: 0.24-0.99), P = 0.0492) as compared to the no AC group. But then the OS, response rate, disease control rate and adverse effects rate were not significant between each group. Therefore, this study suggests that, as long as the combination of gefitinib with antacids is avoided, the combination with antacids should not impair the clinical efficacy of gefitinib. From the results of the sub-analysis, this study suggests that, in particular men, less than 75 years old, PS≧2, pulmonary metastasis, it is preferable to avoid the combination of gefitinib and antacids.
