Erdafitinib — Drug Monograph

Brand names: Balversa

Drug class: Tyrosine Kinase Inhibitor

Mechanism of Action

Pan-FGFR (fibroblast growth factor receptor 1–4) tyrosine kinase inhibitor. Erdafitinib binds competitively and reversibly to the ATP-binding pocket of FGFR1, FGFR2, FGFR3, and FGFR4, blocking receptor autophosphorylation and downstream RAS–MAPK and PI3K–AKT signaling. FGFR3 mutations (R248C, S249C, G372C, Y375C) and FGFR2/3 fusions are present in ~20% of advanced urothelial carcinomas and drive oncogenesis through constitutive kinase activation.

FDA Indications

• Locally advanced or metastatic urothelial carcinoma with susceptible FGFR3 or FGFR2 genetic alterations — adults who have had platinum-containing chemotherapy (NORSE/BLC2001)

Common Side Effects

• Hyperphosphatemia (≥70% — pharmacodynamic marker; used for dose titration)
• Stomatitis/mucositis
• Diarrhea
• Dry mouth
• Nail toxicity (onycholysis, nail ridging)
• Fatigue
• Decreased appetite
• Dysgeusia
• Alopecia
• Palmar-plantar erythrodysesthesia

Clinical Pearl

Erdafitinib requires FGFR2/3 alteration testing before use — approximately 20% of advanced urothelial carcinomas harbor susceptible mutations or fusions. Serum phosphate is the key pharmacodynamic biomarker: rising phosphate confirms target engagement, and the dose-titration protocol (8 mg → 9 mg based on Day 14–21 phosphate) is unique among approved TKIs. Retinal toxicity (RPED) is a class effect of FGFR inhibitors and mandates baseline and monthly ophthalmologic monitoring; any visual change…

Related Therapies & Mechanisms

• Afatinib (Gilotrif) — Tyrosine Kinase Inhibitor
• Alectinib (Alecensa) — Tyrosine Kinase Inhibitor
• Alpelisib (Piqray) — Tyrosine Kinase Inhibitor
• Asciminib (Scemblix) — Tyrosine Kinase Inhibitor