TKT and urinary bladder cancer: In addition, treatment with a reduced tk-JCPyV VLP-SPB concentration of 1 μg in combination with GCV significantly inhibited the growth of tumors from HT-1376 bladder cancer cells with approximately the same effect as 100 μg of tk-JCPyV VLP-SPB (Fig. 5A, right side of the fourth and fifth panels).