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Thomas Flaig, MD


Phase II Trial Update on Potential Bladder-Sparing Treatment

By: Anna Fanelli
Posted: Tuesday, March 14, 2023

Final results from the phase II RETAIN BLADDER trial, presented by Fox Chase Cancer Center researchers at the 2023 American Society of Clinical Oncology (ASCO) Genitourinary (GU) Cancers Symposium (Abstract 438), showed that half of the experimental group of patients with muscle-invasive bladder cancer successfully kept their bladders and reached the 2-year endpoint without developing metastatic cancer. The goal of this study is to identify whether certain patients with muscle-invasive urothelial carcinoma could ultimately undergo bladder-sparing treatment.

“Whether it’s in the next trial or the trial after that, we’re continuously trying to, in an iterative process, improve upon the way we treat patients, preserve quality of life, and provide some options for organ preservation,” commented Daniel M. Geynisman, MD, of Fox Chase Cancer Center, Philadelphia, in a press release.

Researchers compared results for 26 patients with muscle-invasive urothelial carcinoma who showed no evidence of cancer after neoadjuvant chemotherapy and were spared a cystectomy (the active surveillance group) and 45 patients who received the standard of care (the control group); standard treatment consisted of cisplatin-based neoadjuvant chemotherapy followed by cystectomy or chemoradiotherapy. The endpoint for the trial was metastasis-free survival after 2 years.

After 2 years, 46% of the 26 patients in the active surveillance group had not developed metastatic disease and retained their bladders, with no radiation therapy. However, 38% of the active surveillance patients (10 of 26) developed metastatic disease, a statistically similar proportion as was seen in the control group, in which 31% developed metastasis. The 2-year metastasis-free survival was also statistically similar between the two groups—77% with active surveillance and 67% with the standard treatment.

“Would [an] earlier cystectomy have cured the 10 patients in the observation cohort who later developed metastatic disease, and if so, how can we better find out who they are to route them to earlier surgery while sparing cystectomy for those who can safely keep their native bladders?” said coauthor Elizabeth R. Plimack, MD, MS, also of Fox Chase Cancer Center, in a press release.

Disclosure: For full disclosures of the study authors, visit

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