Fibroblast growth factor receptor inhibitor-induced hyperphosphatemia: Lessons for the nephrologist.

Introduction: Fibroblast growth factor inhibitors (FGFRi) are novel cancer drugs that offer new hope for patients with advanced biliary tract cancers and metastatic urothelial tumors. Despite their effectiveness, they often cause hyperphosphatemia.

Materials and methods: We investigated the incidence and characteristics of hyperphosphatemia in patients treated with FGFRi at Northwell Health, comparing findings with clinical trials and the FDA Adverse Event Reporting System database.

Results: 94% of patients in our series developed hyperphosphatemia, predominantly grade 2. The time-to-onset of hyperphosphatemia was longer than noted in clinical trials. Patients on erdafitinib showed a higher-than-expected incidence and grade of hyperphosphatemia.

Conclusion: Collaboration between nephrologists and oncologists is crucial for optimizing treatment benefits and managing side effects. Further research is warranted to refine management strategies and to understand the clinical implications of hyperphosphatemia.