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The following is a summary of “Peritumoral Infiltration of Regulatory T Cells Reduces the Therapeutic Efficacy of Bacillus Calmette–Guérin Therapy for Bladder Carcinoma In Situ,” published in the March 2025 issue of International Journal of Urology by Fukiage et al. 

Bacillus Calmette–Guérin (BCG) is the standard treatment for bladder carcinoma in situ (CIS), but predictive factors for its efficacy remain unknown. 

Researchers conducted a retrospective study on immune cells within 20 μm of tumor cells to identify factors predicting BCG efficacy. 

They analyzed 82 formalin-fixed, paraffin-embedded bladder CIS samples from BCG-treated patients. Responders and non-responders were classified based on relapse. Tissue sections were immunostained for CD4, CD8, and forkhead box P3 (FOXP3). Immune cells within 20 μm of the basement membrane were counted and compared. 

The results showed that peritumoral Treg density and Treg⁺/CD4⁺ ratio were higher in non-responders. Recurrence-free survival (RFS) was longer in the low Treg density and Treg+/CD4+ ratio groups (P = 0.005, P < 0.001). 

They found that higher peritumoral FOXP3-positive cell density and FOXP3⁺/CD4⁺ ratio was linked to shorter relapse intervals. Distant metastasis occurred only in the high FOXP3⁺/CD4⁺ ratio group, suggesting a higher metastatic risk. 

Source: onlinelibrary.wiley.com/doi/10.1111/iju.70044