3319 - Tri-Modality Treatment with or without Pembrolizumab for Selected Patients with Muscle-Invasive Bladder Cancer
Presenter(s)
S. B. Qin1, W. Yu2, X. S. Gao1, H. Hao2, C. J. Zhang3, L. Yao3, H. Z. Li1, and Z. S. He2; 1Department of Radiation Oncology, Peking University First Hospital, Beijing, China, 2Department of Urology, Peking Universtiy First Hospital, Beijing, China, 3Department of Urology, Peking University First Hospital, Beijing, China
Purpose/Objective(s): Tri-modality (TMT) with Pembrolizumab maintenance therapy in muscle-invasive bladder cancer (MIBC) patients was well-tolerated with promising efficacy in the single arm early analysis. However, no direct comparison has published between TMT and TMT with Pembrolizumab. The present study aimed to assess the efficacy and late toxicity of these two treatment strategies in patients with locally advanced bladder cancer. Â
Materials/Methods: We collected individual patient data from patients with MIBC (cT2-4aN0M0), enrolled in two single arm single-site trials in China: One (ChiCTR1800017355; assessing SABR boost to bladder tumor and concurrent radio-chemotherapy) and the other (NCT05072600; assessing Pembrolizumab maintenance following TMT). In each trial, Patients received SABR to the tumor or tumor bed in the bladder followed by conventionally fractionated RT (CFRT) to pelvis and total bladder with concomitant weekly low-dose Gemcitabine chemotherapy. During SABR intravesical installation of isovolumetric saline through urinary catheter ensured adequate bladder filling. Response rate was assessed by cystoscopic evaluation and pelvic MRI or CT.
Results: 112 patients with MIBC (52 from TMT with Pembrolizumab trial and 60 from TMT without Pembrolizumab trial) were included in our analysis. Median follow up was 26 months in all patients. The 2-year progression free survival (PFS) were 71.1%, 75.5% and 67.9% in all patients, TMT with and without Pembrolizumab. The 2-year local control rate (LCR) were 91.1%, 88.9% and 92.8% in all patients, TMT with and without Pembrolizumab. The late ≥ G3 GU toxicity were 5.1% in TMT without Pembrolizumab trial. No patients experienced ≥G3 GI or GU toxicities in TMT with Pembrolizumab trial, but 7.7% patients reported G3 AEs including myocarditis, pneumonitis, and cystitis.
Conclusion: Two strategies of TMT with or without Pembrolizumab maintenance therapy were well-tolerated with promising efficacy in the early analysis. Pembrolizumab following TMT did not provide PFS benefit in our analysis. These results will be confirmed in randomized controlled trials.