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1103 Background: Pembrolizumab is approved for early and advanced triple negative breast cancer (TNBC), and atezolizumab was approved for advanced TNBC. Toxicity of immunotherapy (IO) and immune related adverse events (irAEs) in patients with breast cancer with an underlying autoimmune disease are not well understood as autoimmune disease is often an exclusion criterion in immunotherapy trials. Understanding real-world IO toxicity and irAEs in patients with breast cancer and autoimmune disease may inform clinical decision making. Methods: We studied IO toxicity and irAEs in patients with early and metastatic breast cancer, and underlying autoimmune disease vs. those without autoimmune disease (at IO start) who received IO at an academic institution. A retrospective review was conducted to identify IO toxicity and irAEs (CTCAE v 5.0). Cohorts were compared with Pearson’s chi-squared test (categorical variables) and Wilcoxon rank-sum test (continuous variables), with p 3 months after IO discontinuation) were rare (AD: 12%; non-AD: 4%, p=0.21). Conclusions: A higher overall rate of irAEs was observed in patients with underlying autoimmune disease, including greater immune related transaminitis and flare of the underlying autoimmune disease, suggesting the need for close monitoring of irAEs in this population. Table: see text
Vidula et al. (Sat,) studied this question.