Multicenter, phase II study of trastuzumab and paclitaxel to treat HER2-positive, metastatic gastric cancer patients naive to trastuzumab (JFMC45-1102).

Abstract

4096 Background: The ToGA study indicated that first-line treatment using trastuzumab (T-mab) combined with capecitabine and cisplatin conferred a survival (OS) benefit to patients with HER2-positive metastatic gastric cancer (mGC). However, no reports have described the efficacy and safety of second-line treatment of HER2-positive mGC patients with T-mab who were naïve to the drug. Methods: JFMC45-1102 was a multicenter, Phase II study. Patients positive for HER2 (IHC3+ or IHC2+/FISH+) with gastric adenocarcinoma confirmed histologically; older than ≥ 20 y; who received one or more prior chemotherapies but no prior therapy with T-mab; and normal left ventricular ejection fraction (LVEF ≥ 50%) were eligible. Patients received paclitaxel (80 mg/m2on days 1, 8, and, 15 q4w) plus T-mab (8 mg/kg initial dose, followed by 6 mg/kg q3w). Treatment continued until their disease progressed; there was unacceptable toxicity or patient’s refused further treatment. The primary endpoint was overall response rate (ORR) evaluated according to RECIST ver. 1.0. Threshold and expected ORR were estimated at 15% and 30%, and secondary endpoints included progression free survival (PFS), time to treatment failure (TTF), overall survival (OS) and safety. Results: Fourty-six patients were enrolled between September 2011 and March 2012. Patients characteristics were: gender (M/F) 37/9; median age 69; ECOG PS0/1/2, 35/10/1; unresectable/recurrence 25/21; number of prior treatments (1/2), 41/5. The ORR was 37.2% (95% CI: 23.0-53.3%). The median PFS and TTF were 5.2 months (95% CI 3.9-6.6) and 5.2 months (95% CI 3.9-6.6), respectively. The protocol was discontinued for 27 patients (87.1%) for disease progression, and one patient each (3.2%) for severe adverse events, physician’s recommendation, patient refusal, and treatment related death. Conclusions: Combination chemotherapy of paclitaxel plus T-mab showed promising activity and was tolerated well by patients naïve to T-mab who were positive for HER2 and treated previously for mGC. Clinical trial information: UMIN000006223.