In the multicenter, double-blind, placebo-controlled, randomized controlled phase II/III trial ATTRACTION-4 involving 724 patients with HER2-negative, unresectable, advanced or relapsed gastric cancer or gastroesophageal junction cancer treated with nivolumab in combination with chemotherapy (n = 362) or placebo in combination with chemotherapy (n = 362), the median PFS was 10.45 months in the nivolumab group and 8.34 months in the placebo group (P = 0.0007) at the 11.6-month median follow-up. Here, ERBB2 is linked to gastric cancer.