Based on previous studies, interstitial lung disease, also referred to as pneumonitis, is a rare but shared adverse event in several anti-HER2 drugs, including trastuzumab(9.9%), lapatinib (0.2%), T-DM1 (0.5%), DS-8201 (9.0%), and trastuzumab duocarmazine (7.7%) [17, 18]. The gene discussed is ERBB2; the disease is pneumonitis.