Tolerability and Outcomes of First-Line Pemetrexed-Cisplatin Followed by Gefitinib Maintenance Therapy Versus Gefitinib Monotherapy in Korean Patients with Advanced Nonsquamous Non-small Cell Lung Cancer: A Post Hoc Descriptive Subgroup Analysis of a Randomized, Phase 3 Trial

PURPOSE: We recently reported on a randomized, open-label, phase 3 trial comparing pemetrexed-cisplatin chemotherapy followed by gefitinib maintenance therapy (PC/G) with gefitinib monotherapy in patients with non-small cell lung cancer (NSCLC). Here, we report on a post hoc subgroup analysis of that study assessing the demographics and disposition of the Korean patient subgroup, and comparing the tolerability of PC/G and gefitinib monotherapy and the tumor response with respect to epidermal growth factor receptor (EGFR) status. MATERIALS AND METHODS: Patients, who were ≥ 18 years, chemonaïve, Korean, light ex-smokers/never-smokers with advanced NSCLC, were randomly assigned (1:1) to PC/G or gefitinib monotherapy. Treatment-emergent adverse events (TEAEs) were graded, and tumor response was measured as change in lesion sum from baseline at best response. The study was registered with ClinicalTrials. gov, NCT01017874. RESULTS: Overall, 111 Korean patients were treated (PC/G, 51; gefitinib, 60). Between-arm characteristics were balanced and similar to those of the overall population. Treatment discontinuations due to adverse events were low (PC/G: 1, 2.0%; gefitinib: 7, 11.7%). Overall, 92 patients (82.9%) reported ≥ 1 TEAE (PC/G, 44; gefitinib, 48); few patients (PC/G, 16; gefitinib, 7) reported severe TEAEs; the most frequent was neutropenia (PC/G arm) and elevated alanine aminotransferase (gefitinib arm). The lesion sum was decreased by PC/G treatment in most patients, regardless of EGFR mutation status, while gefitinib monotherapy reduced the lesion sum in EGFR-positive patients but had no effect in EGFR-negative patients. CONCLUSION: Our results confirm that both PC/G and gefitinib were well tolerated in Korean patients, regardless of EGFR status; however, patients with EGFR wild-type NSCLC may not benefit from gefitinib monotherapy.