Erdafitinib

BEFORE TREATMENT: the physician must have confirmation of susceptible FGFR3 gene alteration(s) as determined by a validated test method. DURATION: treatment should continue until disease progression or unacceptable toxicity occurs. VOMITING: if vomiting occurs any time after taking a dose, the next dose should be taken the next day. MISSED DOSE: may be taken as soon as possible, resuming the regular daily schedule the next day; extra tablets should not be taken to make up a missed dose. DOSE REDUCTION SCHEDULE: from 9 mg — 8 mg, then 6 mg, then 5 mg, then 4 mg, then stop; from 8 mg — 6 mg, then 5 mg, then 4 mg, then stop. HYPERPHOSPHATAEMIA: phosphate should be assessed before the first dose and monitored monthly; for phosphate 5.5 mg/dL (1.75 mmol/L) or above, restrict phosphate intake to 600-800 mg/day; below 6.99 mg/dL (2.24 mmol/L) continue at current dose; 7.00-8.99 mg/dL (2.25-2.90 mmol/L) continue treatment and start a phosphate binder with food until phosphate is below 7.00 mg/dL, reducing the dose for a sustained level of 7.00 mg/dL or above for 2 months; 9.00-10.00 mg/dL (2.91-3.20 mmol/L) withhold until phosphate returns below 7.00 mg/dL then restart at the same dose level; above 10.00 mg/dL (3.20 mmol/L) withhold until below 7.00 mg/dL then restart at the first reduced dose level, and discontinue permanently if 10.00 mg/dL or above is sustained for more than 2 weeks. Discontinue permanently for significant alteration from baseline renal function or Grade 3 hypocalcaemia due to hyperphosphataemia. EYE DISORDERS: baseline ophthalmological exam, then monthly ophthalmological examinations including an Amsler grid test during the first 4 months and every 3 months afterwards, and urgently at any time for visual symptoms; withhold and manage per SPC Table 3 (Grade 4 — permanently discontinue). All patients should receive dry eye prophylaxis or treatment with ocular demulcents at least every 2 hours during waking hours. OTHER ADVERSE REACTIONS: Grade 3 — withhold until resolution to Grade 1 or baseline then resume at the next lower dose; Grade 4 — permanently discontinue. HEPATIC IMPAIRMENT: no dose adjustment for mild or moderate impairment; limited data in severe impairment — alternative treatment should be considered. ELDERLY: no specific dose adjustments considered necessary; limited data above 85 years. PAEDIATRIC: there is no relevant use of erdafitinib in the paediatric population for urothelial carcinoma, and safety and efficacy under 18 years have not been established. SOURCE NOTE: eMC §4.4 and §4.8 are truncated at the source-fetch limit and no eMC §4.5 interactions section was retrieved; the tagged interaction entries below come from the US prescribing information in the same bundle.