In the T-DM1 group of the pivotal phase III EMILIA and KATHERINE clinical trials, the incidence of ocular AEs was <10% and included blurred vision (4.5% and 3.9%, respectively), conjunctivitis or dry eye (3.9% and 4.5%, respectively), and increased lacrimation (3.3% and 6%, respectively; Table 2).34 The ORR was 43.6% in the EMILIA trial and was not reported in the KATHERINE trial.35,36 Ocular AEs reported with T-DM1 may be due to on-target toxicity, as HER2 expression has been reported in normal corneal tissue.13 This evidence concerns the gene ERBB2 and Keratoconjunctivitis sicca.