Phase II study of trastuzumab with irinotecan in HER2-positive metastatic or advanced gastric cancer patients previously treated with trastuzumab and failed: HGCSG 1201/OGSG1205.

151Background: Some phase II and III studies of second-line chemotherapy for metastatic or advanced gastric cancer have been reported in recent years. Irinotecan is one of the standard regimen for second-line therapy. On the other hand, the efficacy of continuing trastuzumab (Tmab) beyond progression in patients (pts) who had previously been treated with Tmab plus standard first line chemotherapy has not been reported. We conducted this study to assess the efficacy and safety of Tmab with irinotecan in HER2-positive gastric cancer pts previously treated with Tmab (UMIN ID: 000007636). Methods: Patients with HER2-positive metastatic or advanced gastric cancer who were previously treated with Tmab and failed were included. Pts received Tmab every 3 weeks and irinotecan every 2 weeks. Primary endpoint was response rate (RR), and secondary endpoints were progression-free survival (PFS), six-month survival rate, safety, sub-group analysis by HER2 status (IHC 3+ group, IHC 2+/FISH positive group), and so on. Re...