A phase II trial of capecitabine plus cisplatin (XP) for patients with advanced gastric cancer with early relapse after S-1 adjuvant therapy: XParTS-I trial

In Japan, standard regimens for advanced gastric cancer (AGC) include S-1 chemotherapy. The standard treatment for early relapse after adjuvant chemotherapy with fluoropyrimidine alone is platinum-based chemotherapy, while the standard treatment for early relapse after adjuvant chemotherapy with fluoropyrimidine plus platinum is second-line chemotherapy. To evaluate the efficacy and safety of capecitabine plus cisplatin (XP) treatment for AGC patients who relapse within 6 months after S-1-based therapy, we conducted a multicenter phase II trial (NCT01412294). HER2-negative gastric cancer patients treated with adjuvant chemotherapy including S-1 for more than 12 weeks and relapsed within 6 months were treated with capecitabine 1000 mg/m2 bid for 14 days plus cisplatin 80 mg/m2 on day 1 of a 3-week cycle. The primary endpoint was PFS; secondary endpoints were OS, time to treatment failure, overall response rate (ORR) and safety. Forty patients (median age 64) were enrolled; of those, 37 (92.5%) received adjuvant S-1 monotherapy. Median PFS was 4.4 months (95% CI 3.6–5.1), which was longer than the 2-month protocol-specified threshold (p