A Phase II Study of Tailored-dose S-1 Plus Carboplatin Followed by Maintenance S-1 for Advanced Squamous Cell Lung Cancer: OSAKA-LCSG 1102

Objective A subset analysis of the LETS study suggested that S-1 plus carboplatin was more beneficial than paclitaxel plus carboplatin in terms of the overall survival (OS) in squamous cell lung cancer. However, the benefit of maintenance therapy for squamous cell non-small cell lung cancer (NSCLC) patients is still unknown. We herein report a phase II study to evaluate the efficacy and safety of a tailored dose of S-1 plus carboplatin followed by maintenance S-1 in chemotherapy-naive advanced squamous cell NSCLC. Methods Patients received carboplatin on day 1 plus S-1 on days 1 to 14 every 21 days. The dose of S-1 was determined by the body surface area and creatinine clearance. After four cycles of induction, non-progressive patients continued to receive S-1 until disease progression or unacceptable toxicity occurred. The primary endpoint was an objective response rate (RR) with a threshold value of 15%. The secondary end-points were the progression-free survival (PFS) and OS from enrollment, the PFS in the maintenance phase, and safety. Results In the 33 patients analyzed, the rate of patients who met the primary endpoint was 30.3% (95% confidence interval: 15.6-48.7%), and the disease control rate was 75.8%. The median PFS and OS were 3.5 and 11.3 months, respectively. Ten patients received maintenance S-1, and the median PFS from the beginning of induction treatment was 5.3 months. Grade 3/4 toxicities with a frequency of more than 5% were all controllable. Conclusion Tailored-dose S-1 plus carboplatin followed by maintenance S-1 is an effective and feasible treatment for advanced squamous cell NSCLC.