MRI-based evaluation for predicting pathological response and monitoring reactive angioma evolution in triple-negative breast cancer undergoing neoadjuvant chemoimmunotherapy

Neoadjuvant chemotherapy combined with anti-programmed cell death protein-1 (PD-1) immunomodulators (NACI) has been proven to improve outcomes in triple-negative breast cancer (TNBC). However, the role of MRI in predicting therapeutic response remains underexplored. This study aims to investigate the utility of MRI for early response prediction and longitudinal assessment of reactive angiomatous changes in TNBC patients undergoing NACI therapy. This secondary analysis pooled data from the CamRelief, NeoTENNIS, and other randomized controlled trials (RCTs) investigating NACI in our center between January 2020 and December 2023. Data collected included baseline clinical-pathological characteristics, MRI features, and histopathological response outcomes. MRI evaluation incorporated both BI-RADS descriptors and quantitative apparent diffusion coefficient (ADC) histogram metrics derived from whole-tumor segmentation. Univariate and multivariate two-step logistic regression analyses identified independent predictors of pathological complete response (pCR). A prognostic model integrating significant MRI and histopathological variables was developed. Longitudinal reactive angioma evolution during NACI were analyzed by non-parametric test and chi-square test. A total of 61 TNBC patients undergoing NACI were enrolled. Univariate analysis identified four independent predictors of pCR. While elevated Ki-67 index (p < 0. 001) and CD8-T cell infiltration (p = 0. 004) reflected baseline pathological predictors, washout kinetic curve (p = 0. 004) and reduced medianADC value (p = 0. 021) of MRI provided unique insights with pCR. Moreover, the combined multi-dimensional model achieved a high prediction accuracy, got AUC of 0. 89. Serial MRI monitoring identified transient reactive changes characterized by multiple small masses emerging (mean 8. 82 ± 0. 67 mm) during NACI unrelated to response, peaking at post-cycle-2 MRI, followed by progressive regression. One was histopathologically confirmed as benign reactive angiomatous remodeling. MRI demonstrated dual clinical utility in NACI management of TNBC. The integrative model combining MRI biomarkers with clinicopathological features demonstrated superior predictive accuracy for pCR, while reactive angiomatous remodeling exhibited a transient change.