Phase II study of S-1 in patients with gemcitabine-resistant advanced pancreatic cancer

The primary objective of this study was to assess the efficacy and safety of S-1 in patients with gemcitabine-resistant advanced pancreatic cancer.

Patients with histologically or cytologically proven, advanced pancreatic cancer who had received first-line chemotherapy with gemcitabine were eligible for this study. S-1 was administered orally at a dose of 40 mg/m(2) twice daily for 28 days, followed by 14 days' rest. Treatment was repeated every 6 weeks until disease progression.

Twenty-one patients were enrolled in this study. Grade 3 and 4 toxicities included anorexia in 14% of the patients, abdominal pain in 4.8% and infection without neutropenia in 4.8%. S-1 was discontinued in two patients because of toxicity. Of the 21 eligible patients, 2 (9.5%) achieved a partial response and 9 (43%) had stable disease. A marked decrease (≥50%) in tumor marker (CA19-9) was observed in 5 (28%) of the 18 evaluable patients. The median progression-free survival and the median survival time from the first day of S-1 therapy were 4.1 months (95% CI, 1.3-6.9 months) and 6.3 months (95% CI, 3.6-8.9 months), respectively.

Second-line chemotherapy with S-1 was tolerated with acceptable toxicity and resulted in a relatively high disease control rate in patients with gemcitabine-resistant advanced pancreatic cancer. As an oral agent, S-1 may be a feasible treatment option for this patient population.