Background: The aim of this study is to evaluate the clinical impact of intravesical Bacillus Calmette-Guérin (BCG)-induced changes in blood/urinary immune markers. Methods: Time-course changes in blood/urinary clinical parameters and mRNA expression of 13 genes in urine sediment taken eight times during the treatment course of intravesical BCG (before, every 2 weeks for 8 weeks, and after) in 24 patients with non-muscle invasive bladder cancer. The genes examined include cellular markers of four immune checkpoint proteins (PD-L1, PD-L2, PD-1, and CTLA-4), immunosuppressive cells (regulatory T cells, tumor-associated macrophages, and myeloid-derived suppressor cells), pan-T lymphocytes, B lymphocytes, and neutrophils. Results: Significant transient increase in gene expression was observed for PD-L1, PD-1, FOXP3, and CD204 at 6−8 doses of BCG. The patients were stratified into two groups depending on the number of genes with increased mRNA expression. Fourteen (58%) had 0−1 genes upregulated, while 10 (42%) had 2−4 genes with increased expression. No patient in the 0−1 group experienced recurrence, while 70% of patients in the 2−4 group experienced recurrence (p value = 0.037, hazard ratio = 5.93). Conclusions: Our findings suggested that increases in more than one of PD-L1, PD-1, FOXP3, and CD204, expression in the urine sediments was associated with resistance to BCG treatment.
