A phase II trial of capecitabine plus cisplatin (XP) for patients with advanced gastric cancer who relapsed after S-1 adjuvant therapy, XP after TS-1 adjuvant failure (XParTS).

Abstract

124 Background: For gastric cancer, standard regimens including S-1 for adjuvant and first-line chemotherapy have been established in Japan, while for early relapse after adjuvant therapy there is no standard treatment. In our retrospective analysis, relapse-free interval of less than 6 months was associated with poor progression-free survival (PFS) and overall survival (OS). To evaluate the efficacy and safety of capecitabine plus cisplatin (XP) treatment, for patients with advanced gastric cancer who relapsed within 6 months after S-1 adjuvant therapy, we conducted a multicenter phase II trial in Japan (NCT Identifier: NCT01412294). Methods: Patients who had received adjuvant chemotherapy for gastric cancer including S-1 for more than 12 weeks, thereafter relapsed within 6 months, 20–74 years of age and HER2- negative, were assigned to receive capecitabine 1000 mg/m2 bid for 14 days plus cisplatin 80 mg/m2 (day 1) every 3-week. The primary endpoint was PFS and the secondary endpoints were OS, time to treatment failure, overall response rate (ORR) and safety. Planned sample size was 40 according to median PFS threshold of 2 months. Results: From June 2011 to April 2014, 40 patients were assigned. Median age was 64, 32 males (80%); adjuvant chemotherapy: regimen, S-1 monotherapy (n=34, 85%), and median number of course was 7.0 (3-18). In 40 patients median PFS was 20 weeks (95%CI, 17-24), which was longer than protocol-specified threshold of 2 months. Median OS was 77 weeks (95%CI, 34-NE), ORR was 8/40 (22% including 12 NE cases; 95%CI, 44-74). Most common grade ≥3 adverse events (AEs) were neutropenia (23%), anemia (18%), hypercreatinine (18%), fatigue (13%), diarrhea (7.5%), and anorexia (7.5%). Conclusions: XP was safe and effective for those patients with relatively poor prognosis after S-1 adjuvant failure. Since profile of S-1 and capecitabine was different, XP can be recommended rather than S-1 plus cisplatin, Japanese standard first- line regimen. Clinical trial information: NCT01412294.