9Therefore, regarding new drug development, the therapeutic outcome of 5‐FU is often used as the baseline for comparison in patients with GCa.7 Studies have shown that 15% of patients with GCa are HER2 positive,10, 11 and such patients can be treated with a HER2 inhibitor as alternative once 5‐FU fails. This evidence concerns the gene ERBB2 and temporal arteritis.