Peri-operative treatment patterns in real-world muscle-invasive bladder cancer patients undergoing radical cystectomy in the era of adjuvant immunotherapy.

704 Background: Muscle-invasive bladder cancer (MIBC) has traditionally been managed with radical cystectomy (RC) and pelvic lymph node dissection combined with neoadjuvant (NAD) and/or adjuvant (AD) chemotherapy in eligible patients. In late 2021, adjuvant nivolumab, was approved in the US among patients with certain high-risk of recurrence (HRR) features. Contemporary peri-operative treatment utilization patterns in MIBC patients post-RC is lacking. This study aimed to characterize demographics, clinical features, treatment patterns, and surgical outcomes, in a contemporary cohort of MIBC patients undergoing RC in the post-immunotherapy era. Methods: The US Syapse Learning Health Network Enriched Bladder Cancer Cohort, comprised of patients from community-based practices with cancer registry data supplemented and validated by chart review, was used to identify adults with clinically diagnosed MIBC (T2-T4aN0M0, T1-T4aN1M0) undergoing RC from February 19, 2021 (6-months prior to nivolumab approval) to December 31, 2023, with a minimum 6-month follow-up post-RC (except in cases of patient death). Patients with history of other primary cancer, non-bladder systemic antineoplastic therapies, prior partial cystectomy, NAD radiation, or clinical trial participation were excluded. Real-world HRR following resection was defined using a combination of NAD agent receipt and pathological staging (PS) from RC: received NAD cisplatin-based therapy and pT2-T4a or pN+; or, if patient did not receive NAD cisplatin-based therapy, pT3-4a or pN+. Pathological complete response (pCR) was defined as pT0N0. Results: Of 138 eligible patients, mean age was 66 years, and the majority were male (82%), white (83%), current/former smokers (68%), presented as de novo MIBC (97%), and had urothelial histology (91%). Overall, 49% (67/138) of patients received RC without NAD or AD treatment. Around 46% (64/138) received NAD chemotherapy; of these, one-third achieved pCR (20/61 NAD chemotherapy-treated patients with complete PS data post-RC). The most prevalent NAD regimens were cisplatin + gemcitabine (58%; 37/64) and methotrexate + vinblastine + doxorubicin + cisplatin (30%; 19/64). Only 14% (20/138) of all patients received AD treatment, with 10% (14/138) receiving AD nivolumab. Half of patients had HRR following resection (63/125 patients with complete PS data post-RC). Among the HRR subgroup, 22% (14/63) received AD treatment, with 19% (12/63) receiving nivolumab. Conclusions: In this contemporary cohort of MIBC patients undergoing RC, nearly half received NAD treatment (mainly gemcitabine and cisplatin) while there was limited use of AD treatment. Since FDA approval, AD nivolumab use was 10% among all RC-treated MIBC patients and less than a fifth among HRR patients (nivolumab eligible).