S-1 + Cisplatin with Concurrent Radiotherapy Followed by Surgery for Stage IIIA (N2) Lung Squamous Cell Carcinoma: Results of a Phase II Trial.

Background: To date, no clinical trials on the use of induction therapy before surgery have focused solely on lung squamous cell carcinoma (LSCC). We report the results of the Personalized Induction Therapy-2 (PIT-2) trial, a multicenter phase II study, performed to investigate the efficacy and safety of S-1 + cisplatin with concurrent thoracic radiotherapy (TRT) followed by surgery in patients with stage IIIA (N2) LSCC.

Methods: Patients with pathologically proven stage IIIA (N2) LSCC received induction therapy comprising three cycles of S-1 + cisplatin with concurrent TRT (45 Gy in 25 fractions) followed by surgery. S-1 was administered orally at a dose of 40 mg/m twice daily on days 1-14, in addition to intravenous infusion of cisplatin (60 mg/m) on day 1. The primary endpoint was 2-year progression-free survival (PFS) rate.

Results: Of 45 registered patients, 43 underwent induction therapy. Of the 43 patients, 39 (91%) underwent surgery (35 lobectomies, 3 pneumonectomies, and 1 wedge resection). The 2-year PFS, 2-year overall survival, objective response rate, and pathological complete response rates were 67% (90% confidence interval [CI] 54-78%), 70% (95% CI 53-81%), 86% (95% CI 76-96%), and 39% (95% CI 23-54%), respectively. No new treatment-related adverse events occurred during the induction therapy. One case of 90-day postoperative mortality involving a patient who underwent right pneumonectomy and developed pneumonia after discharge occurred.

Conclusions: Induction therapy using S-1 + cisplatin with concurrent TRT followed by surgery is a feasible and promising treatment approach for stage IIIA (N2) LSCC.