Abstract PD1-05: Real-world adoption, disparities and impact of neoadjuvant chemoimmunotherapy (NACT-IO) in early-stage, high-risk triple negative breast cancer (TNBC)

Abstract Background: NACT-IO has transformed the treatment landscape for early-stage, high-risk TNBC, a clinically aggressive subtype of breast cancer (BC) associated with less favorable survival outcomes. However, the real-world adoption and impact of NACT-IO on BC outcomes are not clearly understood. Using data from a large national hospital-based cancer registry, we examined trends and factors associated with NACT-IO use and pathologic complete response (pCR), and the impact on breast-conserving surgery (BCS) and overall survival (OS). Methods: Patients aged 18 years or older with clinical stage II-III TNBC diagnosed between 2017-2022 who received neoadjuvant chemotherapy (NACT) and underwent surgery were identified in the National Cancer Database. Trends in NACT-IO use and pCR over time were evaluated using the Cochran-Armitage test for time trend. Multivariable logistic regression was used to assess factors associated with receipt of NACT-IO and likelihood of pCR. The association between NACT-IO use and receipt of BCS was also examined using multivariable logistic regression. The impact of pCR on OS was evaluated using a multivariable Cox proportional hazards model with propensity score (PS) weighting and 1:1 matching by year of diagnosis and clinical stage. Results: Among 41,339 patients with early-stage TNBC who received NACT, 28.8% received NACT-IO. NACT-IO use increased significantly over time from 2.9% in 2017 to 81.9% in 2022 (p0.001). Compared to non-Hispanic White (NHW) patients, Black (aOR=0.81; 95%CI 0.76-0.88) and Hispanic (aOR=0.88; 95%CI 0.80-0.97) patients had lower odds of receiving NACT-IO. Patients with Medicaid (aOR=0.89; 95%CI 0.82-0.98), Medicare (aOR=0.82; 95%CI 0.75-0.90), or no insurance (aOR=0.79; 95%CI 0.65-0.95) were also less likely to receive NACT-IO compared to those with private insurance. Higher nodal stage, higher income, and treatment at academic centers were associated with greater odds of NACT-IO use, while older age, higher comorbidity burden and urban residence were associated with lower odds. Patients treated with NACT-IO were more likely to undergo BCS compared to those who received NACT alone (aOR=1.05; 95%CI 1.01-1.11). Among NACT-IO recipients, pCR rates increased from 38.8% in 2017 to 51.6% in 2022 (p0.001). Black patients (aOR=0.88; 95%CI 0.80-0.97), larger tumor size and higher nodal stage were associated with lower pCR rates. Notably, achieving a pCR was associated with significantly lower risk of death (aHR=0.21; 95%CI 0.16-0.27). Conclusions: Since the approval of NACT-IO for early-stage, high-risk TNBC, its use has increased substantially, accompanied by rising pCR rates and greater likelihood of BCS. However, significant disparities persist, with Black and Hispanic patients and those with public or no insurance less likely to receive NACT-IO. Achieving a pCR was strongly associated with improved OS, emphasizing the importance of optimizing treatment delivery and outcomes. These findings highlight the need for equitable access to innovative therapies and ongoing real-world evaluation of their impact to maximize benefit for all eligible patients. Citation Format: I. Jackson, X. Lei, M. Sullivan, S. H. Giordano, M. Chavez-MacGregor. Real-world adoption, disparities and impact of neoadjuvant chemoimmunotherapy (NACT-IO) in early-stage, high-risk triple negative breast cancer (TNBC) abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PD1-05.