Prevalence of FoxP3 + Cells in Canine Tumours and Lymph Nodes Correlates Positively with Glucose Transporter 1 Expression

FoxP3 and IDO in Canine Melanocytic Tumors

Human melanoma is one of the deadliest forms of cancer, with poor prognosis and high resistance to chemotherapy and radiotherapy. The discovery of immunosuppressive mechanisms in the human melanoma microenvironment led to the use of new prognostic markers and to the development of immunotherapies targeting immune checkpoint molecules. Immunoescape mechanisms in canine melanoma have not yet been investigated, and no such immunotherapy has been tested. The aim of this study was to provide preliminary data on the expression of transcription factor forkhead box protein P3 (FoxP3) and indoleamine 2,3-dioxygenase (IDO) in primary canine melanocytic tumors and to investigate their prognostic role. Formalin-fixed, paraffin-embedded samples from 74 canine melanocytic tumors (26 oral melanomas, 23 cutaneous melanomas, and 25 cutaneous melanocytomas) were retrospectively evaluated by immunohistochemistry to explore the expression of FoxP3 and IDO. An increased risk of death due to melanoma was associated with a higher number of FoxP3+ cells per high-power field (FoxP3+/HPF), a higher percentage of CD3+ cells that were also FoxP3+ infiltrating and surrounding the tumor (%FoxP3), and a higher number of IDO+ cells/HPF (IDO+/HPF). A prognostic value for FoxP3 and IDO is suggested by our study, with optimal cutoffs of 14.7 FoxP3+ cells/HPF, 6.1 IDO+ cells/HPF, and 12.5% FoxP3+ cells. Both markers were also associated with tumor type. Multivariable analysis identified IDO+/HPF ( P < .001) as an independent prognostic marker. Even though stratification by diagnosis caused a loss of significance, results from the present study suggest a prognostic role for IDO and FoxP3, possibly related to the establishment of an immunosuppressive microenvironment.

Foxp3 expression in lymph node metastases in patients with head and neck cancer

INTRODUCTION

The prevalence and activity of regulatory T cells in patients with cancer correlates with poor prognosis. These cells are characterized by their expression of Forkhead box protein-3 (Foxp3). Squamous cell carcinoma is the most prevalent type of cancer in the head and neck region with overall poor survival rates, also due to early spread of metastatic cells.

MATERIAL AND METHODS

Primary tumor specimens as well as lymph node specimens harvested during neck dissection of 65 patients with a diagnosis of HNSCC were subjected to immunohistochemical and H-score analysis of Foxp3 expression. Demographics, diagnoses, histopathology and subsequent outcome were analyzed.

RESULTS

The primary cancer was squamous cell carcinoma in all patients (male/female 55:10) with the following tumor locations: oral cavity n = 16, oropharynx n = 28, hypopharynx n = 11 and larynx n = 10 (Stage III n = 18; Stage IVA n = 45; Stage IVB n = 2). The H-score for Foxp3 expression in the primary lesion as well as metastatic lymph nodes was significantly higher in advanced stages compared to early stages with differences among tumor locations, which were not significant. High Foxp3 expression was associated with inferior overall survival rates at a mean follow-up of 83.4 months (6-204 months) Conclusions: Foxp3 expression in HNSCC varied from the anatomical site and correlated positively with tumor stage and was associated with poor prognosis. Therefore, Foxp3 expressions in primary lesions as well as lymphogenic metastases appear to predict high-risk HSNCC patients. Novel therapeutic approaches targeting Foxp3⁺ cells might seem promising for this patient population.

T Lymphocytes in Histiocytic Sarcomas of Flat-Coated Retriever Dogs

Flat-Coated Retriever dogs are predisposed to the development of histiocytic sarcoma (HS), a poorly differentiated, highly malignant neoplasm. The authors have previously documented a significant lymphocytic infiltrate in such tumors. The objective of this study was to examine the presence and expression of regulatory T cells in HS tumor samples. Forty tumors were included in this study. All tumors were immunolabeled for CD3, CD79a, CD25, CD45RA, and FOXP3. The proportion of positive cells was compared between tumors presenting as a localized primary soft tissue mass (soft tissue origin HS) and disseminated HS affecting viscera, especially the spleen (splenic origin HS). By immunohistochemistry, 95% of infiltrating T cells were positive for Foxp3 in all sections, suggesting the presence of regulatory T cells. The proportion of cells positive for FOXP3 was higher in the tumors arising in soft tissues, whereas the proportion of CD45RA-positive cells was higher in the splenic origin HS. Canine HS has an aggressive clinical behavior and is uniformly fatal. The difference in the proportion of tumor-infiltrating lymphocytes positive for these 2 markers in the 2 locations may represent differences in tumor microenvironment between the 2 sites.