(UroToday.com) The Société Internationale D’Urologie (SIU) 2021 annual meeting included a master class on biomarkers in cancer and a presentation by Dr. Wassim Kassouf discussing DDR mutations and response to chemotherapy. For context, Dr. Kassouf noted that for metastatic muscle-invasive bladder cancer, 25% of patients do not response to first-line cisplatin-based chemotherapy, and even among responders the majority will subsequently relapse. For patients with localized muscle-invasive disease, neoadjuvant chemotherapy + radical cystectomy is the standard of care, however, the majority of these patients do not benefit from neoadjuvant chemotherapy. Additionally, this is the cohort of patients that may benefit from an assessment of bladder preservation.