title: Tumor-infiltrating lymphocyte composition, organization and PD-1/ PD-L1 expression are linked in breast cancer.
abstract: The clinical relevance of tumor-infiltrating lymphocytes (TIL) in breast cancer (BC) has been clearly established by their demonstrated correlation with long-term positive outcomes. Nevertheless, the relationship between protective immunity, observed in some patients, and critical features of the infiltrate remains unresolved. This study examined TIL density, composition and organization together with PD-1 and PD-L1 expression in freshly collected and paraffin-embedded tissues from 125 patients with invasive primary BC. Tumor and normal breast tissues were analyzed using both flow cytometry and immunohistochemistry. TIL density distribution is a continuum with 25% of tumors identified as TIL-negative at a TIL density equivalent to normal breast tissues. TIL-positive tumors (75%) were equally divided into TIL-intermediate and TIL-high. Tumors had higher mean frequencies of CD4+T cells and CD19+B cells and a lower mean frequency of CD8+T cells compare with normal tissues, increasing the CD4+/CD8+T-cell ratio. Tertiary lymphoid structures (TLS), principally located in the peri-tumoral stroma, were detected in 60% of tumors and correlated with higher TIL infiltration. PD-1 and PD-L1 expression were also associated with higher TIL densities and TLS. TIL density, TLS and PD-L1 expression were correlated with more aggressive tumor characteristics, including higher proliferation and hormone receptor negativity. Our findings reveal an important relationship between PD-1/PD-L1 expression, increased CD4+T and B-cell infiltration, TIL density and TLS, suggesting that evaluating not only the extent but also the nature and location of the immune infiltrate should be considered when evaluating antitumor immunity and the potential for benefit from immunotherapies.
authors.affiliation: Molecular Immunology Unit, Institut Jules Bordet, Université Libre de Bruxelles, Brussels, Belgium; Breast Cancer Translational Research Laboratory J-C Heuson, Institut Jules Bordet, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Laurence
authors.identifier: 0000-0002-3751-0819
authors.initials: L
authors.lastname: Buisseret
authors.affiliation: Molecular Immunology Unit, Institut Jules Bordet, Université Libre de Bruxelles , Brussels, Belgium.
authors.forename: Soizic
authors.initials: S
authors.lastname: Garaud
authors.affiliation: Department of Pathology, Institut Jules Bordet , Brussels, Belgium.
authors.forename: Alexandre
authors.initials: A
authors.lastname: de Wind
authors.affiliation: Department of Pathology, GZA Ziekenhuizen, Sint-Augustinus campus , Wilrijk, Belgium.
authors.forename: Gert
authors.initials: G
authors.lastname: Van den Eynden
authors.affiliation: Molecular Immunology Unit, Institut Jules Bordet, Université Libre de Bruxelles , Brussels, Belgium.
authors.forename: Anais
authors.initials: A
authors.lastname: Boisson
authors.affiliation: Molecular Immunology Unit, Institut Jules Bordet, Université Libre de Bruxelles , Brussels, Belgium.
authors.forename: Cinzia
authors.identifier: 0000-0001-6782-8708
authors.initials: C
authors.lastname: Solinas
authors.affiliation: Molecular Immunology Unit, Institut Jules Bordet, Université Libre de Bruxelles , Brussels, Belgium.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Gu-Trantien
authors.affiliation: Molecular Immunology Unit, Institut Jules Bordet, Université Libre de Bruxelles , Brussels, Belgium.
authors.forename: Céline
authors.initials: C
authors.lastname: Naveaux
authors.affiliation: Molecular Immunology Unit, Institut Jules Bordet, Université Libre de Bruxelles , Brussels, Belgium.
authors.forename: Jean-Nicolas
authors.initials: JN
authors.lastname: Lodewyckx
authors.affiliation: Molecular Immunology Unit, Institut Jules Bordet, Université Libre de Bruxelles, Brussels, Belgium; Flow Cytometry Facility, Institut Jules Bordet, Brussels, Belgium.
authors.forename: Hugues
authors.initials: H
authors.lastname: Duvillier
authors.affiliation: Department of Pathology, Institut Jules Bordet , Brussels, Belgium.
authors.forename: Ligia
authors.initials: L
authors.lastname: Craciun
authors.affiliation: Department of Surgery, Institut Jules Bordet , Brussels, Belgium.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Veys
authors.affiliation: Department of Pathology, Institut Jules Bordet , Brussels, Belgium.
authors.forename: Denis
authors.initials: D
authors.lastname: Larsimont
authors.affiliation: Department of Medicine Institut Jules Bordet , Brussels, Belgium.
authors.forename: Martine
authors.initials: M
authors.lastname: Piccart-Gebhart
authors.affiliation: Université de Montréal, Centre de Recherche du CHUM , Montreal, Quebec, Canada.
authors.forename: John
authors.initials: J
authors.lastname: Stagg
authors.affiliation: Breast Cancer Translational Research Laboratory J-C Heuson, Institut Jules Bordet, Université Libre de Bruxelles , Brussels, Belgium.
authors.forename: Christos
authors.initials: C
authors.lastname: Sotiriou
authors.affiliation: Molecular Immunology Unit, Institut Jules Bordet, Université Libre de Bruxelles , Brussels, Belgium.
authors.forename: Karen
authors.identifier: 0000-0002-1150-1295
authors.initials: K
authors.lastname: Willard-Gallo
keywords: Breast cancer; PD-1; PD-L1; tertiary lymphoid structures; tumor-infiltrating lymphocytes