Subclassifying triple-negative breast cancers and its potential clinical utility

Area of Science:

• Oncology
• Pathology
• Immunotherapy

Background:

• Accurate molecular subtyping of triple-negative breast cancer (TNBC) is crucial for personalized treatment strategies.
• Understanding the clinicopathologic features and survival correlates of TNBC subtypes is essential for effective patient management.
• Assessing PD-L1 expression and its relationship with immunotherapeutic outcomes in Chinese TNBC patients is a key area of investigation.

Purpose of the Study:

• To characterize the clinicopathologic features of different TNBC subtypes.
• To identify factors associated with patient survival in TNBC.
• To evaluate PD-L1 expression and its correlation with immunotherapeutic treatment outcomes in Chinese TNBC patients.

Main Methods:

• Utilized immunohistochemical (IHC) markers (CD8, FOXC1, AR) based on histologic features to classify TNBC subtypes.
• Classified 93 TNBC patients into Luminal Androgen Receptor (LAR), Immunomodulatory (IM), Basal-like Immune-Suppressed (BLIS), and Mesenchymal (MES) subtypes.
• Assessed PD-L1 expression and mismatch repair deficiency (dMMR) in relation to clinicopathologic characteristics and survival.

Main Results:

• Classified 93 TNBC patients into LAR (23), IM (24), BLIS (39), and MES (7) subtypes.
• PD-L1 positivity was found in 49.6% of cases, predominantly in the IM subtype.
• Significant differences in histologic grade, pT stage, and PD-L1 status were observed among subtypes, but no significant differences in recurrence-free or breast cancer-specific survival were found.

Conclusions:

• IHC marker-based TNBC molecular subtyping provides a foundation for precision treatment.
• PD-L1 expression is a relevant factor for immunotherapeutic treatment planning in TNBC.
• Mismatch repair deficiency (dMMR) is unlikely to be a substantial predictor of immunotherapeutic efficacy in TNBC patients.