757 - A Randomized, Single Center Phase II Trial of Capecitabine Plus Cisplatin versus TS-1 Plus Cisplatin as First Line Treatment in Patients with advanced or Metastatic Gastric Cancer

Abstract

ABSTRACT Background Platinum agents and oral fluoropyrimidines are widely used in the treatment of advanced gastric cancer. This study was aimed to evaluate the efficacy and safety of two combination regimens (capecitabine plus cisplatin [XP] vs S-1 plus cisplatin [SP]) in patients with untreated recurrent or metastatic gastric cancer. Methods Patients diagnosed as untreated recurrent or metastatic gastric cancer were randomly assigned to either capecitabine (2500 mg/BSA/day; day 1-14) plus cisplatin (60 mg/BSA/day; day 1), every 3 weeks or TS-1 (80-120 mg/day; day 1-14) plus cisplatin (60 mg/BSA/day; day 1), every 3 weeks. Primary end point was overall response rate (ORR), accessed by RECIST criteria (ver. 1.0). The secondary end point was progression free survival (PFS), overall survival (OS), and toxicities. Results 86 patients were anticipated to be enrolled, but 51 patients were randomized to XP (25 patients) arm or SP (26 patients) arm because enrollment was slower than expected. ORR of XP and SP was 52% (13 of 25 assessable patients) vs. 44% (15 of 25 assessable patients), and no significant differences were found (P = 0.778). OS of XP vs. SP was 10.3 months (95% CI; 4.8-15.8) vs. 12 months (95% CI; 9.5-14.5), with no differences (P = 0.785). PFS was 4.6 months (95% CI; 4.6-5.2), 4.4 months (95% CI; 2.2-6.6) each (P = 0.68). The incidence of grade 3-4 neutropenia of XP vs. SP was 40% vs. 43.2%. There were no febrile neutropenia in XP arm, but 7.7% in SP arm. Grade 3-4 thrombocytopenia was 12%, 3.8% each. Other grade 3-4 toxicities were; Nausea (4% vs. 0%), Stomatitis (12% vs. 3.8%), Hand-foot syndrome (16% vs. 0%), Diarrhea (0% vs. 3.8%). Median relative dose intensity of capecitabine vs. TS-1 was 78.7% (range 51.9-116.7%), 87.5% (range 57.1-166.7%). Conclusion There were no significant differences in ORR, OS, and PFS between XP vs. SP arm. The incidence of grade 3-4 neutropenia was similar in both arms, but thrombocytopenia was relatively more common in XP arm. SP was more tolerable than XP in non-hematologic toxicities. Considering the usual dosage of capecitabine in monotherapy is 2500 mg/BSA/day, capecitabine 2500 mg/BSA/day combined with cisplatin 60 mg/BSA may be overdosed, and higher rate of non-hematologic toxicity can be explained. Dosage of capecitabine when combined with cisplatin, needs to be further adjusted for routine use. Disclosure All authors have declared no conflicts of interest.