A major diagnostic challenge in bladder-sparing therapy for T4 tumors is the "fibrotic scar." When a large tumor responds to therapy, it leaves behind fibrotic tissue that is indistinguishable from residual cancer on an MRI, making it nearly impossible to confirm a true complete response.

Experts caution that the new consensus definition of cCR, combining imaging and cystoscopy, is for clinical trials only. Applying it prematurely in routine practice could harm patients, as its correlation with true pathologic response is still being validated with modern therapies.

The trial's 57.1% pathologic complete response (pCR) rate is deceptively conservative. It categorized patients who responded well but declined surgery as non-responders, suggesting the treatment's true biological efficacy is even higher than the already impressive reported figure.

In the SUNRISE 2 trial, 44% of patients had no detectable tumor after pre-treatment resection. This high baseline inflates the final clinical complete response (CR) rates (e.g., 59% in the control arm), making CR a misleading indicator of the actual therapeutic benefit, which was a much smaller improvement over baseline.

While bladder preservation is a key goal, there is an unavoidable risk. Forgoing definitive local treatment like surgery means a subset of patients will not be cured by systemic therapy alone and will miss their opportunity for a potentially curative operation, a crucial ethical consideration.

While circulating tumor DNA (ctDNA) is a powerful prognostic marker, it is not yet part of the formal "clinical complete response" definition for bladder-sparing trials. Experts lack data on its ability to predict the superficial, non-muscle invasive relapses common in this setting.

An expert argues forcefully that the PD-L1 biomarker should be "ditched" in bladder cancer. Citing its repeated failure to predict overall survival benefit across multiple major trials, it is deemed an oversimplified and unreliable tool that leads to both over- and under-treatment of patients.

New bladder-sparing trials mandate nine cycles of EV-Pembro to replicate the conditions of successful surgical trials. This conservative approach ignores that patient response is front-loaded while toxicity is back-loaded, likely overtreating many patients to ensure comparable efficacy.

With pathologic complete response rates approaching 67% in patients completing neoadjuvant EV-Pembro, a majority of cystectomies are now removing cancer-free bladders. This creates an ethical and clinical imperative to rapidly launch prospective trials to validate bladder preservation strategies and avoid overtreatment.