Infiltration of CD3⁺ and CD68⁺ cells in bladder cancer is subtype specific and affects the outcome of patients with muscle-invasive tumors.

OBJECTIVES: Urothelial carcinoma (UC) aggressiveness is determined by tumor inherent molecular characteristics, such as molecular subtypes, as well as by host reactions directed toward the tumor. Cell types responsible for the host's response include tumor-infiltrating lymphocytes (TILs) and tumor-associated macrophages (TAMs). The aim of the present investigation was to explore the immunological response in relation to UC molecular subtypes and to evaluate the prognostic effect of TIL and TAM counts in tissue sections from muscle-invasive (MI) tumors. METHODS AND MATERIALS: Tissue microarrays with 296 tumors spanning all pathological stages and grades were analyzed with antibodies for CD3, CD8, FOXP3, CD68, and CD163. Cases were classified into the following molecular subtypes: urobasal, genomically unstable, and squamous cell carcinoma-like using a combination of immunohistochemistry and histology. The Cox regression and Kaplan-Meier analyses were performed with progression-free survival and disease-specific survival as end points.
RESULTS: UC molecular subtypes demonstrate different degrees of immunological responses; the urobasal subtype induces a weak response, the genomically unstable subtype induces an intermediate response, and the squamous cell carcinoma-like subtype induces a strong response. These subtype specific responses are independent of tumor stage and include both TILs and TAMs. The presence of infiltrating CD3(+) TILs was significantly associated with good prognosis in the MI cases (P<0.01). This positive association was modulated by the presence of CD68(+) TAMs. The strongest association with poor survival was observed for a high ratio between CD68 and CD3 (P = 7×10(-5)).
CONCLUSION: UC molecular subtypes induce immunological responses at different levels. A high CD68/CD3 ratio identifies a bad prognosis group among MI UC cases.