Programmed Death Ligand 1 (PDL1) Expression in Neoadjuvant Triple-Negative Breast Cancer: Association With...

Area of Science:

• Oncology
• Immunology
• Pathology

Background:

• Programmed death ligand 1 (PDL1) expression is a biomarker for immune evasion and a predictor of response to PDL1 inhibitors in various cancers.
• Triple-negative breast cancer (TNBC) is a subtype of breast cancer that often lacks targeted therapies, making immune checkpoint inhibitors a potential treatment option.
• Limited data exists on PDL1 expression in Pakistani breast cancer patients, highlighting the need for local studies.

Purpose of the Study:

• To evaluate the frequency of PDL1 expression in TNBC patients in Pakistan.
• To determine the correlation between PDL1 expression and clinicopathological characteristics and prognostic factors in TNBC.
• To assess the association between PDL1 expression and response to neoadjuvant chemotherapy in TNBC.

Main Methods:

• A cross-sectional study was conducted on 128 biopsy-proven TNBC cases treated with neoadjuvant chemotherapy.
• PDL1 immunohistochemical staining was performed on pre-chemotherapy needle biopsies.
• PDL1 expression was quantified using the combined positive score (CPS), with CPS ≥10 considered PDL1-positive.

Main Results:

• PDL1 expression was observed in 18.8% of TNBC cases.
• A significant association was found between PDL1 expression and neoadjuvant chemotherapy response (p < 0.01).
• PDL1-positive cases exhibited a higher pathological complete response (pCR) rate (66.7%) compared to PDL1-negative cases (25%) and a lower frequency of high residual cancer burden (RCB-II/III).

Conclusions:

• PDL1 expression is relatively low in Pakistani TNBC patients but is significantly associated with a better response to neoadjuvant chemotherapy.
• PDL1 positivity correlates with lower Ki67 index and older age.
• Routine PDL1 testing in TNBC is recommended to predict neoadjuvant chemotherapy response and identify patients eligible for immunotherapy.