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.