In univariable analyses, pre-treatment shortness of breath (hazard ratio [HR] 3.9, 95% confidence interval [CI] 1.3–11.7), greater number of prior treatments (HR 1.2 per line, 95% CI 1.0-1.4), triple-negative breast cancer (HR 4.9, 95% CI 1.8–13.0), low HER-2 status (4.00 (95% CI: 1.43–11.11) and pre-treatment ILAs (HR 17, 95% CI 6.5–46) were associated with pneumonitis. This evidence concerns the gene ERBB2 and triple-negative breast carcinoma.