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Purpose: To compare C-C chemokine receptor type 5 (CCR5) expression in urothelial carcinoma tissue to other common malignancies using a specific CCR5 inhibitor-based assay.

Methods: We used an immunohistochemistry (IHC) assay to compare the expression of  CCR5 in urothelial carcinoma to different types of common cancer. The IHC assay was based on labeled PRO140 (PRO140 CCR5 Hu IgG4a), a CCR5 inhibitor with potential therapeutic uses. The expression levels were compared using Percent Scores and H-Score methods. 

Results: Quantification of CCR5 expression utilized a panel of 63 evaluable samples from 9 cancer indications as follows: 6 UC, 7 non-small cell lung (NSCL) adenocarcinoma, 9 NSCL squamous cell carcinoma, 5 triple negative breast cancer, 5 breast cancer, 7 pancreatic cancer, 9 colorectal cancer, 7 head, and neck cancer, and 8 sarcoma. Overall, most of the 63 cases evaluated tended to have either H-Scores >175 (highly reactive) (24/63) or <100 (low or non-reactive) (32/63). Urothelial cancer had the highest expression (H score=183.3), while sarcoma exhibited the most moderate expression of CCR5 (H score =23.6).

Conclusions: We show, for the first time, a high expression of CCR5 in the tissue of urothelial carcinoma using an assay based on a safe and effective receptor inhibitor. Our findings may have therapeutic implications if validated in more extensive studies.