Bladder sparing management for muscle-invasive bladder cancer after a complete clinical response: ready for prime time?-a narrative review.

Background and Objective: A standard of care for muscle-invasive bladder cancer (MIBC) is cisplatin-based neoadjuvant chemotherapy (NAC) followed by radical cystectomy (RC). Given recent improvements in NAC and the morbidity associated with RC, bladder-sparing therapy has been investigated as a promising treatment for patients with MIBC who experience a complete clinical response (CCR) to systemic therapy. However, clinical staging is unreliable, making it challenging to determine ideal candidates for bladder-sparing therapy. Our primary objective is to review the efficacy of NAC, strategies for determining a CCR as a surrogate for a complete pathologic response, and the emerging role of imaging, tumor genomics, and biomarkers in selecting candidates for bladder-sparing therapy. Methods: We surveyed the literature for studies investigating the outcomes of current treatment modalities for MIBC and methods for determining a CCR following systemic therapy as well as the impact this has on pathologic staging. Studies employing imaging, tumor biomarkers, and genomics were included. Key Content and Findings: Clinical staging with cystoscopy or transurethral resection shows significant discordance with final pathology, with high rates of understaging. Multiparametric magnetic resonance imaging (mpMRI) has shown strong utility in determining the presence of MIBC, but it has yet to reliably identify CCR. Meanwhile, somatic DNA damage repair mutations and biomarkers such as circulating and urinary tumor DNA are strong predictors of recurrence, showing promise in predicting and monitoring a CCR to systemic therapy. Multiple ongoing trials are currently assessing the use of biomarkers and genomic analyses in determining eligibility for bladder-sparing therapy. Conclusions: While no one method has reliably demonstrated the ability to detect a true CCR, a multimodal approach involving imaging, biomarkers, and genomic analyses holds promise. We eagerly await the results of clinical trials investigating these tools, which may allow for the safe recommendation of bladder-sparing therapy.