Bladder Tumor-Focused Adaptive Radiotherapy Shows Feasibility in Phase 2 Trial

Dose-escalated adaptive image-guided radiotherapy (DART) has shown to be safe and effective for patients with muscle invasive bladder cancer (MIBC), according to the phase 2 RAIDER trial. The study enrolled 345 patients across 49 clinical trial sites in Europe and Australia, assigning them to receive standard whole bladder radiotherapy (WBRT), standard-dose adaptive radiotherapy (SART), or DART.

The primary endpoints focused on meeting radiotherapy dose constraints and assessing treatment-emergent radiotherapy-related toxicity. Results showed that 86% to 90% of DART participants met the mandatory medium plan dose constraints. Safety data indicated low rates of grade 3 or higher treatment-emergent radiotherapy-related toxicity.

Efficacy outcomes revealed a 2-year locoregional disease control rate of 74% in the DART arm, with no significant difference compared to the WBRT and SART arms. The 2-year overall survival rate was 80% in the DART arms, similar to the WBRT and SART arms. The study concluded that DART enables radiotherapy dose escalation to over 86% of patients’ bladder tumors without a significant increase in toxicity, achieving promising tumor control and survival rates similar to cystectomy.

The RAIDER trial's phase 2 is ongoing, with final completion anticipated for March 2029. The findings support further investigation into DART for bladder cancer treatment, highlighting its potential as a viable alternative to cystectomy with low rates of salvage cystectomy.