Dose-Escalation Study of Thoracic Radiotherapy in Combination With Pemetrexed Plus Cisplatin Followed by Pemetrexed Consolidation Therapy in Japanese Patients With Locally Advanced Nonsquamous Non–Small-Cell Lung Cancer

BackgroundPemetrexed has radiosensitizing potential when evaluated in vitro in combination with platinum-containing compounds and radiation. We determined the recommended dose (RD) of thoracic radiotherapy (TRT) with a concurrent chemotherapy combination of pemetrexed and cisplatin in Japanese patients with nonsquamous non–small-cell lung cancer (NSCLC).Patients and MethodsEligible patients were histologically confirmed as having locally advanced nonsquamous NSCLC. Study treatment consisted of 2 phases: concurrent chemoradiation and consolidation. In the concurrent chemoradiation phase, all patients received pemetrexed 500 mg/m2 plus cisplatin 75 mg/m2 on day 1 of a 21-day interval for 3 cycles. The first 6 patients were given 60 Gy concurrently at level 1 dose (L1D). If dose-limiting toxicity (DLT) occurred in < 2 patients at L1D, radiation was escalated to 66 Gy (level 2 dose [L2D]).ResultsEighteen patients were treated and completed chemoradiotherapy; 12 completed the consolidation phase. In the concurrent chemoradiation phase, 1 patient experienced 2 DLTs [grade 3 anorexia and diarrhea] at L1D. Because no DLT was observed at L2D, it was determined to be the RD. Common toxicities ≥grade 3 were neutropenia and leukopenia. At L1D, 1 patient each experienced grade 2 and grade 3 pneumonitis, and 2 patients experienced grade 2 esophagitis. Six patients experienced grade 2 pneumonitis and 3 patients experienced grade 2 esophagitis at L2D. Fifteen patients achieved partial response (PR), 2 had stable disease (SD), and 1 had progressive disease (PD).ConclusionExpected toxicities from concurrent chemoradiation were not worsened with concurrent TRT at a total dose of 66 Gy combined with pemetrexed in Japanese patients with locally advanced (LA) nonsquamous NSCLC.