RAINFALL before RAINBOW—an illusion or reality?

Combination with fluoropyrimidines and platinum-based agents have been used as first-line therapy for metastatic gastric/gastroesophageal junction cancer (GC) resulting in a median progression-free survival (PFS) of 5–6 months and a median overall survival (OS) of 10–15 months. Trastuzumab, a monoclonal antibody against human epidermal growth factor receptor 2 (HER2), significantly improved the OS of HER2-positive GC patients, which consists of around 15% of patients (1). However, other randomized studies failed to show benefits of several molecular targeting agents for GC in first-line (2-7), thus development of more effective combination is important.