Abstract P2-08-06: Comparative Analysis of Pathological Outcomes and Toxicity in Hispanic vs Non-Hispanic Patients Receiving Keynote 522 Regimen: A Retrospective Single Center Experience

Abstract Introduction: There is limited data on the comparative outcomes between Hispanic and non-Hispanic patients in real-world settings, as this patient population was underrepresented in the original trial. This retrospective real-world study examines pathological responses and treatment-related toxicities among Hispanic and non-Hispanic patients undergoing the Keynote 522 regimen for locally advanced triple-negative breast cancer. Methods: We conducted a retrospective analysis of patients with early stage TNBC treated on KN522 regimen and undergoing surgery at our institution from July 2021 to June 2024. Data collection included demographics, clinical stage, HER2 status, node status, and treatment pattern. Outcomes measured were pathological complete response (pCR) rate, and incidence of adverse effects (AEs). Statistical analyses to compare outcomes between Hispanic and non-Hispanic patients was performed using R v4.2. Results: The study included 59 female patients, with 66.1% being Hispanic and a median age of 52. Pathological complete response (pCR) was achieved in 56% of patients overall, with no differences based on node status or tumor size. pCR rates were similar between Hispanic (46.1%) and non-Hispanic (50.7%) patients. Non-Hispanics had a significantly higher rate of drug dose modification (40% vs 12%), but treatment delays, drug omissions, and time from last treatment to surgery were comparable. Hispanic patients experienced higher fatigue rates (89% vs 60%). Hospitalization rates and severe (≥grade 3) toxicities, including neutropenia, anemia, and neuropathy, were similar between both groups. Conclusion: This retrospective study supplements trial data from the real world with comparable pCR rates, with no difference based on tumor size or node status. It revealed no statistical difference in pCR rates between Hispanic and non-Hispanic patients undergoing the Keynote 522 regimen for locally advanced triple-negative breast cancer. Although non-Hispanic patients required more frequent dose modifications, overall treatment delays, drug omissions, and time from last treatment to surgery were similar across groups. Notably, Hispanic patients reported higher rates of fatigue. Hospitalization and severe toxicities, such as neutropenia, anemia, and neuropathy, were comparable between the two groups. These findings highlight the need for tailored management strategies to address specific toxicity profiles and support equitable outcomes across diverse patient populations. Citation Format: Jay Parekh, Ranjit Banwait, Sarah Shaker, Aditi Sharma, Marcela Mazo-Canola. Comparative Analysis of Pathological Outcomes and Toxicity in Hispanic vs Non-Hispanic Patients Receiving Keynote 522 Regimen: A Retrospective Single Center Experience [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr P2-08-06.