Abstract 59P
Background
Bladder cancer, the most common malignancy of the urinary tract, is divided into non-muscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC). Intravesical Bacillus Calmette-Guérin (BCG) therapy is the standard treatment for high-risk NMIBC, but recurrence and progression remain significant challenges. This review aims to explore immune checkpoint inhibitors (ICIs), particularly pembrolizumab, as emerging therapies for BCG-unresponsive NMIBC.
Methods
This systematic review and meta-analysis followed PRISMA guidelines. We included clinical trials and randomized controlled trials (RCTs) focused on BCG-unresponsive NMIBC treated with ICIs. Statistical analysis was performed using R software, while Risk of bias was assessed using RoB 2 for RCTs and ROBINS-I for non-randomized studies.
Results
A total of nine studies were included, with six single-arm clinical trials and three non-randomized controlled trials. The efficacy of ICIs varied, with complete response (CR) rates of 0.36 at three months, 0.25 at six months, and 0.18 at twelve months. Pembrolizumab demonstrated superior efficacy compared to other ICIs at twelve months. The proportion of patients undergoing radical cystectomy (RC) was 0.14, with lower rates in those treated with atezolizumab. Safety data revealed a high incidence of treatment-related adverse events (TrAEs), with a pooled incidence of 0.67 for grade 1-2 TrAEs and 0.15 for grade 3-5. Immune-related adverse events (IrAEs) were reported in 0.22 of patients for grade 1-2 and 0.06 for grade 3-5. Serious adverse events occurred in 0.15 of patients, with a higher occurrence in the atezolizumab subgroup compared to pembrolizumab (0.21 vs. 0.11).
Conclusions
Immune checkpoint inhibitors, particularly pembrolizumab, offer a promising treatment option for patients with BCG-unresponsive NMIBC, demonstrating favorable efficacy and a manageable safety profile. However, variability in treatment response and adverse event rates highlights the need for further large-scale, randomized trials to better understand the long-term outcomes and optimize patient selection for ICIs.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.