Phase II study of trastuzumab and cisplatin as first-line therapy in patients with HER2-positive advanced gastric or gastroesophageal junction cancer.

INTRODUCTION: HER2 over-expression and/or amplification are present in 9-38% of gastric or gastroesophageal junction (GEJ) cancers and are correlated to poor outcome. We conducted a multicentre phase II trial to evaluate trastuzumab in combination with cisplatin in patients with untreated HER2-positive advanced gastric or GEJ cancer.

MATERIALS AND METHODS: Chemo-naïve patients with measurable, non-resectable, advanced or metastatic gastric or GEJ adenocarcinoma, with HER2 over-expression and/or amplification (IHC 3+, or IHC 2+ and FISH+), age ≥18 years, ECOG ≤2, left ventricle ejection fraction ≥50% and adequate organ function were eligible. Treatment consisted of trastuzumab (8 mg/kg on cycle 1 day 1 as loading; 6 mg/kg in subsequent cycles) and cisplatin (75 mg/m(2)), both intravenously on day 1, every 21 days.

RESULTS: Twenty-two out of 228 patients (10%) were HER2- positive and were included in this phase II trial. The median age was 66 years and ECOG 0/1 was 41%/59%. The median number of cycles was 4 (range 1-41). The confirmed ORR was 32% and disease control was achieved in 64% of patients. Median time to progression was 5.1 months. Grade 3 adverse events included asthenia (27%), neutropenia (18%), anorexia (14%), diarrhoea (9%) and abdominal pain (9%). There were no grade 4 toxicities or treatment-related deaths. Higher baseline HER extracellular domain (ECD) levels were associated with better outcome in terms of response and survival.

CONCLUSIONS: Trastuzumab in combination with cisplatin is an active regimen and has a favourable toxicity profile in advanced HER2-positive gastric or gastroesophageal cancers.