Impact of obesity on immune-related adverse events in patients with diagnosis of triple-negative breast cancer.

e13156 Background: Obesity is a significant risk factor for breast cancer and is associated with a poor prognosis. Immune checkpoint inhibitors (ICIs) are the standard of care in the treatment of early-stage and metastatic triple-negative breast cancer (TNBC). ICI treatment is associated with several immune-related adverse events (irAEs); however, predictive biomarkers have not yet been identified. In this study, we hypothesized that obesity is associated with an increased risk of irAEs in patients with TNBC. Methods: A retrospective analysis of patients with TNBC treated with ICIs was conducted using the TriNetX research network using the appropriate ICD-10 code. This study incorporated PD-1/PD-L1 and CTLA-4 inhibitors. The inclusion criterion was patients receiving ICIs. The study population was further stratified into two cohorts based on the body mass index (BMI): obese with a BMI of >30 and non-obese with a BMI of 20-29.9. Descriptive statistics were used to summarize the baseline characteristics of the obese and nonobese cohorts. The p-values were derived using z-tests to compare the difference in risks of irAEs between the two cohorts. The index event was the initiation of ICI and the time window for irAEs was chosen as one year from the index event. Results: The study included 176 patients with TNBC receiving ICI treatment, with 68% being White, 18% African American, and 10% Hispanic or Latino. All patients were female, with a median age of 54.5 years. 81% of patients were obese, while 19% were non-obese. No significant difference was observed in the risk of cardiotoxicity, fatigue, mucositis, colitis, or pituitary dysfunction between the obese and non-obese groups. However, obese patients had an increased risk of developing hepatitis (0.135 vs 0, p= 0.004) and diabetes (0.179 vs 0, p= 0.002). Non-obese patients had a higher risk of developing thyroid dysfunction (0.175 vs 0, p <0.001)(Table). Conclusions: Our findings indicate that in TNBC patients treated with ICIs, higher BMI correlates with increased liver dysfunction and endocrine disorders, particularly thyroid disorders and pancreatic insufficiency. Further studies with larger sample sizes are needed to validate these findings and understand the underlying mechanisms of metabolic syndromes and immune-related adverse events for tailoring treatment options. Immune-related adverse events in obese vs non-obese TNBC patients. Adverse Effect Risk in obese group Risk in non-obese group P Value Thyroid Dysfunction 0 0.175 <0.001 Pituitary dysfunction 0.137 0.175 0.547 Mucositis 0.135 0.185 0.441 Cardiotoxicity 0.135 0.179 0.497 Colitis 0.137 0.179 0.518 Hepatitis 0.135 0 0.004 Fatigue 0.164 0.208 0.552 Diabetes 0.179 0 0.002