ERBB2 and pneumonitis: While studies reporting on patients who received an anti-HER2 drug as first-line therapy reported no ILD-related deaths, studies assessing later line therapy reported a 0.2% incidence of ILD-related death (n = 16, including ILD [n = 5 (< 0.1%)], pneumonitis [n = 10 (0.1%)], and pulmonary fibrosis [n = 1 (< 0.1%)]); however, among the studies included in this review, more patients received anti-HER2 therapy as later line therapy (n = 9,749) than as first-line therapy (n = 140).