TLSs are frequently present in TNBC and are closely associated with TILs. TILs provide additional prognostic information in patients with TNBC with a higher pTNM stage.

Abundant TILs are an independent prognostic factor in HR-/HER2+ breast cancers. Evaluation of TILs in HR-/HER2+ breast cancers may provide valuable information regarding the prognosis of patients treated using adjuvant chemotherapy and trastuzumab.

Tumor-infiltrating lymphocytes (TILs) have been known for their strong prognostic and predictive significance in triple-negative breast cancer (TNBC). Several mechanisms for TIL influx in TNBC have been elucidated. Major histocompatibility complex class II (MHC-II) is an essential component of the adaptive immune system and is generally restricted to the surface of antigen-presenting cells. However, it has been reported that interferon-gamma signaling may induce MHC-II in almost all cell types, including those derived from cancer. We aimed to examine the relationship between MHC-II expression in tumor cells and the amount of TILs in 681 patients with TNBC. Further, the prognostic significance of MHC-II and the association of MHC-II with a couple of molecules involved in the interferon signaling pathway were investigated using immunohistochemical staining. Higher MHC-II expression in tumor cells was associated with the absence of lymphovascular invasion (p = 0.042); larger amounts of TILs (p < 0.001); frequent formations of tertiary lymphoid structures (p < 0.001); higher expression of myxovirus resistance gene A, one of the main mediators of the interferon signaling pathway (p < 0.001); and higher expression of double-stranded RNA-activated protein kinase, which can be induced by interferons (p = 0.008). Moreover, tumors that showed high MHC class I expression and any positivity for MHC-II had larger amounts of CD4- and CD8-positive T lymphocytes (p < 0.001). Positive MHC-II expression in tumor cells was associated with better disease-free survival in patients who had lymph node metastasis (p = 0.009). In conclusion, MHC-II expression in tumor cells was closely associated with an increase in TIL number and interferon signaling in TNBC. Further studies are warranted to improve our understanding regarding TIL influx, as well as patients’ responses to immunotherapy.

PurposeThe tertiary lymphoid structure (TLS) is an important source of tumor-infiltrating lymphocytes (TILs), which have a strong prognostic and predictive value in triple-negative breast cancer (TNBC). A previous study reported that the levels of CXCL13 mRNA expression were associated with TLSs, but measuring the gene expression is challenging in routine practice. Therefore, this study evaluated the MECA79-positive high endothelial venule (HEV) densities and their association with the histopathologically assessed TLSs in biopsy samples. In addition, the relationship of TLSs with the CXCL13 transcript levels and clinical outcomes were examined.Materials and MethodsA total of 108 TNBC patients treated with neoadjuvant chemotherapy (NAC) were studied. The amounts of TILs and TLSs were measured histopathologically using hematoxylin and eosin–stained slides. The HEV densities and TIL subpopulations were measured by immunohistochemistry for MECA79, CD3, CD8, and CD20. CXCL13mRNA expression levels using a NanoString assay (NanoString Technologies).ResultsThe mean number of HEVs in pre-NAC biopsies was 12 (range, 0 to 72). The amounts of TILs and TLSs, HEV density, and CXCL13 expression showed robust correlations with each other. A lower pre-NAC clinical T stage, higher TIL and TLS levels, a higher HEV density, CD20-positive cell density, and CXCL13 expression were significant predictors of a pathologic complete response (pCR). Higher CD8-positive cell density and levels of CXCL13 expression were significantly associated with a better disease-free survival rate.ConclusionMECA79-positive HEV density in pre-NAC biopsies is an objective and quantitative surrogate marker of TLS and might be a valuable tool for predicting pCR of TNBC in routine pathology practice.

The level of tumor-infiltrating lymphocytes and presence of tertiary lymphoid structures are significant prognostic and predictive factors in primary breast cancer. However, the understanding about differences in tumor-infiltrating lymphocytes and tertiary lymphoid structures at various metastatic sites or between primary breast tumors and metastatic sites is limited. A total of 335 cases of metastatic breast cancer from four metastatic sites (lung, liver, brain, and ovary) were included. We analyzed the percentages of tumor-infiltrating lymphocytes and presence of tertiary lymphoid structures in the primary and metastatic sites. The mean level of tumor-infiltrating lymphocytes in the lung metastases was higher than in the liver, brain, ovary, and matched primary tumors, while metastatic tumors of the liver and brain showed lower levels of tumor-infiltrating lymphocytes than primary tumors. Tertiary lymphoid structures were only found in the lung and liver, and in cases of brain metastases the change of tertiary lymphoid structures from present to absent significantly affected the level of tumor-infiltrating lymphocytes in metastases compared with that in matched primary tumors. Patients with a lower histological grade, hormone receptor positivity in primary tumors and metastases, a lower level of tumor-infiltrating lymphocytes and absence of tertiary lymphoid structures in primary tumors, a higher level of tumor-infiltrating lymphocytes and presence of tertiary lymphoid structures in metastases, and lung metastases showed significantly better overall survival. Our results showed that metastatic breast tumors in the lung had more tumor-infiltrating lymphocytes than did tumors at other sites and matched primary tumors. In addition, the presence of tertiary lymphoid structures in metastatic sites is a critical factor for the level of tumor-infiltrating lymphocytes.

Tumor-infiltrating lymphocytes (TILs) in triple-negative breast cancer (TNBC) have a strong prognostic and predictive significance. However, the mechanism of TIL influx in TNBC is unclear. Expression of major histocompatibility complex class I (MHC I) on the tumor cell is essential for the effective killing of tumor by cytotoxic TILs. In our current study, human leukocyte antigen (HLA) expression was inversely correlated with estrogen receptor (ER) expression in normal and cancerous breast tissue and positively correlated with TILs in breast cancer. The ER score was inversely correlated with TILs in breast cancer. HLA-A and CD8B gene expression was negatively correlated with ESR1 and positively correlated with interferon-associated gene expression in The Cancer Genome Atlas (TCGA) data. Negative correlation between ESR1 and HLA and positive correlation between interferon-associated and HLA gene expression were also confirmed in Cancer Cell Line Encyclopedia (CCLE) data. Taken together, our data suggest that a lower expression of HLA in luminal-type tumors might be associated with low level of TILs in those tumors. Further investigation of the mechanism of higher HLA expression and TIL influx in TNBC may help to boost the host immune response.

Adoptive cell transfer (ACT) of ex vivo expanded tumor-infiltrating lymphocytes (TILs) has been successful in treating a considerable proportion of patients with metastatic melanoma. In addition, some patients with several other solid tumors were recently reported to have benefited clinically from such ACT. However, it remains unclear whether ACT using TILs is broadly applicable in breast cancer, the most common cancer in women. In this study, the utility of TILs as an ACT source in breast cancers was explored by deriving TILs from a large number of breast cancer samples and assessing their biological potentials. We successfully expanded TILs ex vivo under a standard TIL culture condition from over 100 breast cancer samples, including all breast cancer subtypes. We also found that the information about the percentage of TIL and presence of tertiary lymphoid structure in the tumor tissues could be useful for estimating the number of obtainable TILs after ex vivo culture. The ex vivo expanded TILs contained a considerable level of central memory phenotype T cells (about 20%), and a large proportion of TIL samples were reactive to autologous tumor cells in vitro. Furthermore, the in vitro tumor-reactive autologous TILs could also function in vivo in a xenograft mouse model implanted with the primary tumor tissue. Collectively, these results strongly indicate that ACT using ex vivo expanded autologous TILs is a feasible option in treating patients with breast cancer.

The prognostic significance of tumor-infiltrating lymphocytes and immune signals has been described previously in triple-negative breast cancer (TNBC). Furthermore, recent studies have shown that immunologic parameters are relevant for the response to neoadjuvant chemotherapy (NAC) in breast cancer as well as for outcomes after adjuvant chemotherapy. However, immune signals are variable, and which signals are important is largely unknown. We, therefore, evaluated the expression of immune-related genes in TNBC treated with NAC. We retrospectively evaluated biopsy tissue from 55 patients with primary TNBC treated with NAC (anthracycline, cyclophosphamide, and docetaxel) against the NanoString nCounter GX Human Immunology Panel (579 immune-related genes). Higher expression of cytotoxic molecules, T cell receptor signaling pathway components, cytokines related to T helper cell type 1 (Th1), and B cell markers was associated with a pathologic complete response (pCR). Higher expression of NFKB1, MAPK1, TRAF1, CXCL13, GZMK, and IL7R was significantly associated with pCR, higher Miller-Payne grade, and lower residual cancer burden class. Expression of NFKB1, TRAF1, and CXCL13genes, in particular, was significantly correlated with a longer disease-free survival rate. Conversely, patients those who failed to achieve a pCR showed increased expression of genes related to neutrophils. Higher expression of cytotoxic molecules, T cell receptor signaling pathway components, Th1-related cytokines, and B cell markers is correlated with pCR and survival in TNBC patients treated with NAC. Our results suggest that the activation status of neutrophils may provide additional predictive information for TNBC patients treated with NAC.