For patients with life-threatening metastatic urothelial cancer and poorly controlled diabetes, experts advise starting enfortumab vedotin (EV) without delay. The immediate cancer threat outweighs the risks of a high hemoglobin A1C. Aggressive glucose monitoring and early endocrinologist involvement are initiated simultaneously to manage the hyperglycemia.
When a patient's bladder cancer has both FGFR and HER2 alterations, the preferred second-line treatment is an FGFR inhibitor like erdafitinib. This choice is driven by its supportive Phase 3 trial data, which represents a higher level of evidence compared to the smaller studies for trastuzumab deruxtecan (TDXD) in this cancer type. Patient preference for oral versus IV therapy is also a factor.
While hyperphosphatemia is an expected on-target effect of the FGFR inhibitor erdafitinib, clinicians find that side effects like stomatitis, diarrhea, dry mouth, and fatigue more frequently lead to dose reductions or discontinuation. Proactive management of these seemingly secondary toxicities is crucial for keeping patients on this effective therapy.
While useful for initial genomic screening, using circulating tumor DNA (ctDNA) to monitor treatment response in the metastatic setting is discouraged. A positive ctDNA result in a patient with negative scans can create significant patient anxiety without a clear clinical action, as treatment decisions are still typically based on radiographic progression.