State-of-the-Art Imaging in Antibody-Drug Conjugate Treatment for Advanced Bladder Cancer.

Antibody-drug conjugates (ADCs) have revolutionized the treatment landscape for advanced bladder cancer, particularly enfortumab vedotin and trastuzumab deruxtecan, which target Nectin-4 and human epidermal growth factor receptor 2 (HER 2), respectively. These ADCs have shown substantial efficacy, improving survival in patients who have progressed after chemotherapy and immunotherapy. Imaging plays a pivotal role in ADC-based therapy, extending beyond diagnosis and staging to assessing treatment response, detecting recurrence, and evaluating toxicity. Computed tomography (CT), multiparametric magnetic resonance imaging (MRI), and fluorodeoxyglucose positron emission tomography (FDG-PET) are widely used for these purposes. Despite the efficacy of ADCs, resistance mechanisms such as antigen loss and payload resistance continue to pose challenges, necessitating the development of next-generation ADCs. Response assessment largely relies on Response Evaluation Criteria in Solid Tumors (RECIST) 1.1, with growing interest in multiparametric MRI for evaluating complete response in bladder lesions. Additionally, imaging helps identify ADC-related toxicities, including pneumonitis and gastrointestinal complications. Radiologists must be aware of these evolving therapeutic and imaging paradigms to optimize patient management. The integration of imaging with ADC-based treatment requires a multidisciplinary approach to improve outcomes. This review highlights the critical role of imaging in ADC therapy and underscores the need for radiologists to adapt to these advancements in bladder cancer treatment.