[PD-L1 expression and PD-1/PD-L1 inhibitors in breast cancer]

Area of Science:

• Oncology
• Immunotherapy
• Cancer Research

Background:

• Immune checkpoint inhibitors (ICIs) targeting PD-1/PD-L1 have revolutionized cancer treatment.
• Their efficacy is well-established in various solid tumors, including melanoma and lung cancer.
• Breast cancer represents a critical area for exploring ICI applications.

Purpose of the Study:

• To review current data on PD-L1 expression in breast cancer.
• To synthesize preliminary clinical outcomes of PD-1/PD-L1 inhibitors in breast cancer patients.
• To highlight the association between PD-L1 expression and breast cancer characteristics.

Main Methods:

• Literature review of studies on PD-L1 expression in breast cancer.
• Analysis of preliminary clinical trial data for PD-1/PD-L1 inhibitors in breast cancer.
• Synthesis of information on prognostic and predictive factors.

Main Results:

• PD-L1 expression in breast cancer is heterogeneous and linked to poor prognostic factors and aggressive subtypes.
• Prognostic value of PD-L1 is controversial via immunohistochemistry but potentially favorable in triple-negative cancers at the mRNA level.
• Early trials show efficacy of PD-1/PD-L1 inhibitors in refractory metastatic breast cancer, particularly triple-negative subtype.

Conclusions:

• PD-1/PD-L1 inhibitors demonstrate preliminary efficacy in metastatic breast cancer, especially triple-negative.
• Ongoing trials are evaluating ICIs in both metastatic and neoadjuvant settings.
• Identifying predictive biomarkers for ICI response is crucial for optimizing breast cancer treatment.