Neoadjuvant cisplatin-based chemotherapy followed by selective bladder preservation chemoradiotherapy in muscle-invasive urothelial carcinoma of the bladder: Post hoc analysis of two prospective studies.

e16583 Background: Bladder preservation chemoradiotherapy (CRT) in patients with a clinical complete response (cCR) following cisplatin-based neoadjuvant chemotherapy (NAC) is a promising treatment strategy for muscle-invasive bladder urothelial carcinoma (MIBC). A combined analysis of raw data from two prospective phase II studies (Sung HH, Investig Clin Urol 2022; Kim H, Cancer Res Treat 2023) was performed to better evaluate the feasibility of selective bladder preservation CRT. Methods: The analysis was based on primary efficacy data from two independent studies, including 76 MIBC patients receiving NAC followed by bladder preservation CRT. The efficacy data included metastasis-free survival (MFS) and disease-free survival (DFS). For the present analysis, starting point of survival was defined as the date of commencing CRT. Results: Among 76 patients, 66 had a cCR following NAC. Sixty-four patients received gemcitabine/cisplatin (GC) combination chemotherapy in neoadjuvant setting, and 12 received nivolumab plus GC. Bladder preservation CRT following NAC was generally well-tolerated, with low urinary tract symptoms being the most common late complication. With a median follow-up of 64 months, recurrence was recorded in 43 patients (57%): intravesical only (n = 20), metastatic only (n = 16), and both (n = 7). In 27 patients with intravesical recurrence, transurethral resection and BCG treatment was given to 17 patients. Salvage cystectomy was performed in 10 patients. Median DFS was 46.3 (95% CI, 25.1-67.5) months, and the median MFS was not reached. Neither DFS nor MFS appeared to be affected by any of the baseline characteristics. However, DFS was significantly longer in patients with a cCR than in those without (HR, 0.465; 95% CI, 0.222-0.976). Conclusions: The strategy of NAC followed by selective bladder preservation CRT based on the cCR is feasible in the treatment of MIBC. A standardized definition of cCR is needed to better assess disease status post-NAC.