W1131 is a potent STAT3 inhibitor, triggering ferroptosis. W1131 suppresses cancer progression in gastric cancer cell subcutaneous xenograft model, organoids model, and PDX model. W1131 effectively alleviates chemical resistance of cancer cells to 5-FU. W1131 regulates cell cycle, DNA damage response, and oxidative phosphorylation, including IL6-JAK-STAT3 pathway and ferroptosis pathway[1].