Pemazyre (pemigatinib) is a kinase inhibitor that targets FGFR1/2/3. It inhibits tumor growth by blocking abnormal FGFR signaling pathways, but its use must strictly adhere to medication guidelines.

Precautions for the Use of Pemazyre (Pemigatinib)

Confirmations Before Medication Use

Genetic Testing: The presence of FGFR2 fusion or rearrangement must be confirmed through FDA-approved testing; otherwise, the drug must not be used.

Ophthalmic Examination: A comprehensive ophthalmic examination including optical coherence tomography (OCT) is required before starting medication. Subsequent re-examinations should be conducted every 2 months (for the first 6 months) and then every 3 months thereafter.

Dosage and Administration

Standard Regimen: 13.5mg orally once daily, taken continuously for 14 days followed by a 7-day drug holiday (a 21-day cycle), until disease progression or intolerable toxicity occurs.

Administration Requirements: Swallow the tablet whole; do not crush or chew it. It can be taken with or without food, but must be taken at a fixed time each day.

Management of Missed Doses: If a dose is missed by more than 4 hours or vomiting occurs after taking the dose, skip that dose and take the next dose as scheduled.

Ocular Toxicity

Retinal Pigment Epithelial Detachment (RPED): It may cause blurred vision, floaters, or photopsia. The incidence rate is approximately 6%, and urgent ophthalmic evaluation is required.

Dry Eye: It occurs in 27% of patients, and the use of artificial tears is recommended for relief.

Hyperphosphatemia

Mechanism of Occurrence: FGFR inhibition leads to increased blood phosphorus levels (incidence rate up to 92%).

When blood phosphorus levels exceed 5.5mg/dL, initiate a low-phosphorus diet.

When blood phosphorus levels exceed 7mg/dL, phosphorus-lowering treatment is required and dosage adjustment should be considered.

When blood phosphorus levels exceed 10mg/dL, the drug must be suspended and the dosage reduced.

Contraception Requirements

Female patients must use effective contraception during medication and for 1 week after discontinuing the drug.

Male patients with reproductive partners must also use contraception simultaneously.

Dosage Adjustments for Pemazyre (Pemigatinib) in Special Populations

Drug Interactions

Strong/Moderate CYP3A Inhibitors (e.g., itraconazole): The dosage needs to be reduced to 9mg or 4.5mg.

CYP3A Inducers (e.g., rifampicin): Concomitant use should be avoided, otherwise it may reduce the efficacy of the drug.

Hepatic and Renal Impairment

Mild to Moderate Hepatic or Renal Impairment: No dosage adjustment is required.

Severe Impairment: The efficacy has not been established, and the drug should be used with caution.