Immune Checkpoint Profiling in Humanized Breast Cancer Mice Revealed Cell-Specific LAG-3/PD-1/TIM-3 Co-Expression and Elevated PD-1/TIM-3 Secretion

Abstract

Checkpoint blockade is particularly based on PD-1/PD-L1-inhibiting antibodies. However, an efficient immunological tumor defense can be blocked not only by PD-(L)1 but also by the presence of additional immune checkpoint molecules. Here, we investigated the co-expression of several immune checkpoint proteins and the soluble forms thereof (e.g., PD-1, TIM-3, LAG-3, PD-L1, PD-L2 and others) in humanized tumor mice (HTM) simultaneously harboring cell line-derived (JIMT-1, MDA-MB-231, MCF-7) or patient-derived breast cancer and a functional human immune system. We identified tumor-infiltrating T cells with a triple-positive PD-1, LAG-3 and TIM-3 phenotype. While PD-1 expression was increased in both the CD4 and CD8 T cells, TIM-3 was found to be upregulated particularly in the cytotoxic T cells in the MDA-MB-231-based HTM model. High levels of soluble TIM-3 and galectin-9 (a TIM-3 ligand) were detected in the serum. Surprisingly, soluble PD-L2, but only low levels of sPD-L1, were found in mice harboring PD-L1-positive tumors. Analysis of a dataset containing 3039 primary breast cancer samples on the R2 Genomics Analysis Platform revealed increased TIM-3, galectin-9 and LAG-3 expression, not only in triple-negative breast cancer but also in the HER2+ and hormone receptor-positive breast cancer subtypes. These data indicate that LAG-3 and TIM-3 represent additional key molecules within the breast cancer anti-immunity landscape.

Neoadjuvant radiotherapy in ER+, HER2+, and triple-negative -specific breast cancer based humanized tumor mice enhances anti-PD-L1 treatment efficacy

“…HTM were generated as previously described ( 29 ) and illustrated in Supplementary Figure 1A . In more detail, human cord blood samples (n=23) were obtained from the Department of Gynecology and Obstetrics (University Medical Center Regensburg) upon signed informed consent and subsequently diluted 1:1 with PBS.…”

PD‐L2 Expression in Breast Cancer Promotes Tumor Development and Progression

“…In recent years, numerous reports have revealed that PD-L2 is elevated in many cancers, including ovarian cancer [ 11 ], lung adenocarcinoma [ 12 ], gastric cancer [ 13 , 14 ], and esophageal squamous cell carcinoma [ 15 ]. In contrast, only a few studies have demonstrated a connection between PD-L2 and breast cancer [ 16 , 17 , 18 ]. Therefore, it is of significant clinical importance to explore PD-L2 expression within breast cancer.…”

“…Among them, anti-PD-1 or anti-PD-L1 antibodies have altered the treatment of advanced cancers, such as melanoma [ 28 , 29 ], lung cancer [ 30 ], kidney cancer [ 31 ], or various others [ 32 , 33 ]. However, immunotherapy has shown limited success in breast cancer, and the effect of PD-L2 on regulating breast cancer remains largely unknown [ 16 , 17 , 18 ].…”