Exploring Racial Differences in Pathological Complete Response to Neoadjuvant Chemotherapy and Pembrolizumab in Triple-Negative Breast Cancer

Background Triple-negative breast cancer (TNBC) is a high-risk subtype marked by aggressive behavior and limited treatment options. Neoadjuvant chemoimmunotherapy with pembrolizumab has improved pathologic complete response (pCR) rates in early-stage TNBC. However, racial disparities persist in TNBC outcomes, and data on how these disparities affect response to chemoimmunotherapy remain limited. This study evaluates racial differences in pCR rates among TNBC patients treated with neoadjuvant pembrolizumab-based therapy, using data from a regional health system. Findings Among 94 patients, the overall pCR rate was 58.5%. White patients had higher pCR rates (67.5%) than Black patients (52.8%), though the difference was not statistically significant. Stratified analyses revealed more pronounced disparities. Among patients 50 and younger, White patients had a significantly higher pCR rate (84.2%) compared to Black patients (41.2%). In stage III disease, White patients also had higher pCR rates (66.7%) than Black patients (37.5%). Clinically relevant mutations were strongly associated with higher pCR (81.3%), especially in White patients (90.9%). Trends in pCR also varied by BMI and stage, with lower rates seen in obese patients and those with more advanced disease. Conclusions Although pembrolizumab improves pCR rates in early-stage TNBC, disparities persist, particularly among younger Black patients and those with advanced disease. These differences may be driven by genetic, biological, or socio-environmental factors. The findings highlight the importance of tailoring treatment strategies to individual patient profiles and underscore the need for larger, prospective studies that include racial and genetic diversity to inform equitable care in TNBC.