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Programmed Death-Ligand 1 (PD-L1) as Immunotherapy Biomarker in Breast Cancer
Martín Núñez Abad1, Silvia Calabuig-Fariñas2,3,4,5, Miriam Lobo de Mena1
1Department of Medical Oncology, Hospital General Universitario de Valencia, 46014 Valencia, Spain.
Cancers
|January 21, 2022
Summary
Programmed death-ligand 1 (PD-L1) shows promise as a biomarker in breast cancer (BC) subtypes. Immunotherapy targeting PD-1/PD-L1 is effective for triple-negative BC, but its role in other subtypes needs further research.
Area of Science:
- Oncology
- Immunology
- Medical Biomarkers
Background:
- Breast cancer (BC) is a leading cause of cancer death globally, with a significant portion diagnosed at advanced stages or relapsing, indicating its incurable nature.
- Programmed death-ligand 1 (PD-L1) is an immune checkpoint molecule involved in T-cell regulation and implicated in various cancers, including BC.
- The PD-1/PD-L1 pathway is a target for cancer immunotherapy, aiming to restore anti-tumor immune responses.
Purpose of the Study:
- To review the role of PD-L1 as a biomarker across different breast cancer subtypes.
- To analyze clinical trials of immune checkpoint inhibitors targeting the PD-1/PD-L1 axis in breast cancer.
- To evaluate the clinical utility and predictive value of PD-L1 in breast cancer treatment decisions.
Main Methods:
- Systematic review of diverse clinical trials involving anti-PD-1/PD-L1 immunotherapy in breast cancer.
- Inclusion of prospective and retrospective cohort studies assessing PD-L1 expression in breast cancer.
- Analysis of treatment outcomes and prognostic correlations based on PD-L1 status and breast cancer subtype.
Main Results:
- PD-L1 expression appears correlated with a worse prognosis in the hormone receptor-positive (HR+) breast cancer subtype.
- Immune checkpoint inhibitors targeting the PD-1/PD-L1 axis show significant response rates in triple-negative breast cancer (TNBC), particularly when combined with chemotherapy.
- The predictive utility of PD-L1 as a biomarker remains uncertain for most breast cancer subtypes beyond TNBC.
Conclusions:
- While immunotherapy offers a new treatment avenue for TNBC, the role of PD-L1 as a predictive biomarker is not yet established for all breast cancer subtypes.
- Predictive responses to immunotherapy vary based on tumor stage, highlighting the need for further investigation.
- Enhanced understanding of the tumor microenvironment and the identification of novel biomarkers or composite scores are crucial for optimizing patient selection for PD-1/PD-L1 blockade therapies.
