A phase II study of S-1 in relapsed small cell lung cancer

S-1 is a new oral fluoropyrimidine derivative designed to enhance anticancer activity and reduce gastrointestinal toxicity. This phase II trial aimed to evaluate S-1 in patients with relapsed small cell lung cancer (SCLC). SCLC patients who had experienced treatment failure with ≥1 prior chemotherapies were eligible. Patients were required to have an Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0-2 and adequate organ function. Treatment consisted of oral S-1 at 40 mg/m² twice/day for 28 days every 6 weeks. Twenty-six patients were enrolled, 85% of whom were males. The median age was 68 years (range, 33-79) and 81% of the patients had a performance status of 0-1, and 46% of the patients had relapse-sensitive SCLC. An objective response was obtained in only 1 patient (3.8%), and the median progression-free survival (PFS) was 1.1 months. The median overall survival was 5.3 months, and the 1-year survival rate was 23%. The most common grade 3/4 toxicities included neutropenia (7.7%), leukopenia (7.7%), anemia (7.7%), hyponatremia (7.7%), rash (7.7%), infection (7.7%) and diarrhoea (3.8%). None of the patients developed febrile neutropenia and no deaths were attributed to treatment. In conclusion, S-1 has minimal single-agent activity in relapsed SCLC.