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Published on: October 30, 2013
Decoding Immune Mechanisms in BCG-unresponsive Non-muscle Invasive Bladder Cancer
Mohamad Abou Chakra1, Igor Duquesne2, Michael A O'Donnell1
1Department of Urology, University of Iowa Health Care, Iowa City, IA 52242, USA.
Frontiers in Bioscience (Landmark Edition)
|May 30, 2026
Summary
Bacillus Calmette-Guérin (BCG) therapy for non-muscle-invasive bladder cancer (NMIBC) often fails due to immune evasion within the tumor microenvironment. Novel intravesical immunotherapies show promise but require combination strategies targeting these escape mechanisms.
Area of Science:
- Oncology
- Immunology
- Cancer Research
Background:
- Non-muscle-invasive bladder cancer (NMIBC) represents a significant portion of bladder cancer diagnoses.
- Intravesical Bacillus Calmette-Guérin (BCG) is the standard treatment for intermediate- and high-risk NMIBC, but treatment failure occurs in up to 40% of patients.
- Radical cystectomy, while effective, involves substantial morbidity, necessitating bladder-sparing alternatives.
Purpose of the Study:
- To review the immunologic mechanisms underlying BCG therapy efficacy and failure in NMIBC.
- To examine multifactorial immune evasion mechanisms within the tumor microenvironment (TME) that contribute to BCG resistance.
- To highlight emerging intravesical immunotherapies for BCG-unresponsive NMIBC.
Main Methods:
- Review of immunologic mechanisms of BCG therapy and immune evasion in NMIBC.
- Identification and discussion of ten principal immune suppression mechanisms in the TME.
- Summary of emerging intravesical immunotherapies and their platforms.
Main Results:
- Ten key immune suppression mechanisms in the TME hinder BCG efficacy, including myeloid-derived suppressor cells, regulatory T cells, PD-1/PD-L1, NKG2A/HLA-E, CD6-ALCAM signaling, T cell exhaustion, and cancer-associated fibroblasts.
- These mechanisms disrupt antigen presentation, suppress immune responses, and promote tumor progression.
- Emerging immunotherapies like nadofaragene firadenovec, nogapendekin alfa inbakicept-pmln, cretostimogene grenadenorepvec, and detalimogene voraplasmid show promise but lack comparative data.
Conclusions:
- Understanding TME immune dynamics is crucial for developing effective bladder-sparing alternatives to BCG.
- Combination strategies targeting multiple immune escape mechanisms are needed for BCG-unresponsive NMIBC.
- Further research with comparative studies and predictive biomarkers is essential for optimizing novel immunotherapy selection.
