Relationship between hyperphosphatemia with infigratinib (BGJ398) and efficacy in FGFR3-altered advanced/metastatic urothelial carcinoma (aUC).

576 Background: Infigratinib (BGJ398) is a potent and selective FGFR1–3 inhibitor with significant clinical activity in aUC bearing FGFR3 alterations. A common adverse event is hyperphosphatemia, a class effect associated with FGFR1 inhibition. We sought to better understand the relationship between hyperphosphatemia and response to infigratinib in patients with aUC. Methods: Eligible patients had aUC with activating FGFR3 mutations/fusions and...