Antitumor activity of an oncolytic measles virus against canine urinary bladder transitional cell carcinoma cells

The prognosis of canine transitional cell carcinoma (TCC) of urinary bladder is generally poor because it is difficult to diagnose at early stages and conventional therapies, such as surgical resection and/or chemotherapy, are often not curative treatments. Based on our previous report that recombinant measles virus (rMV-SLAMblind) therapy could be a new treatment for canine mammary tumor, the applicability of rMV-SLAMblind in canine urinary bladder TCC was examined in this study. A canine TCC cell line was established from a TCC patient dog by transplanting a piece of the tumor mass into an immunodeficient mouse and then isolating the primary TCC cells from the grown tumor mass. The primary cultured cells, named TCC-NU1, express nectin-4, a receptor for rMV-SLAMblind infection. The rMV-SLAMblind infected TCC-NU1 cells, and dose-dependently showed cell cytotoxicity. Moreover, intratumoral administration of rMV-SLAMblind in a xenograft model bearing TCC-NU1 cells significantly suppressed the tumor growth reducing the endpoint mass of tumors in treated mice compared to control mice. These results suggest that virotherapy with rMV-SLAMblind be a new candidate therapy for canine TCC.