In a phase 1 trial involving patients with HER2‐positive or HER2‐low advanced solid tumors, grade ≥ 3 treatment‐related events were infrequent, and the most common toxicities were fatigue (32%) and ocular events (conjunctivitis, 31%; dry eye, 31%) [46]. The gene discussed is ERBB2; the disease is Keratoconjunctivitis sicca.