Infigratinib is used to treat cholangiocarcinoma with FGFR2 fusion or rearrangement, and its adverse reactions involve multiple systems. Key monitoring areas include ocular effects, phosphate metabolism, and skin and mucosal toxicity.

I. Ocular Adverse Reactions

1. Retinal Pigment Epithelial Detachment

It can cause blurred vision, and some patients have no obvious symptoms.

Ophthalmic examinations, including optical coherence tomography, are required before treatment, at 1 month, at 3 months, and every 3 months thereafter.

If visual symptoms occur, immediate referral to ophthalmology is required, with follow-up every 3 weeks until resolution or discontinuation.

Treatment may need to be withheld depending on the condition, and most cases resolve after discontinuation.

2. Dry Eye and Other Ocular Problems

Dry eye is common and can be relieved with artificial tears or lubricating eye gels.

Other manifestations include keratitis, increased tearing, eyelash changes, and blurred vision.

If visual changes persist or worsen, inform the doctor promptly.

II. Phosphate Metabolism and Soft Tissue Mineralization

1. Hyperphosphatemia

Infigratinib can increase serum phosphate, which is a common pharmacodynamic effect.

Elevated serum phosphate can lead to soft tissue mineralization, cutaneous calcification, vascular calcification, and myocardial calcification.

Serum phosphate levels should be monitored throughout treatment.

2. Management Principles

When serum phosphate rises, phosphate-lowering therapy should be initiated and the dose of phosphate binders adjusted.

If serum phosphate rises significantly, treatment should be withheld, and after phosphate recovery, it should be evaluated whether to reduce or restart the dose.

In case of life-threatening hyperphosphatemia, treatment should be permanently discontinued.

If muscle cramps, perioral numbness, or tingling occur, inform the doctor immediately.

III. Adverse Reactions in Other Systems

1. Skin and Nail Toxicity

Nail toxicity is common, including onycholysis, nail bed inflammation, nail discoloration, and nail dystrophy.

Alopecia, palmar-plantar erythrodysesthesia syndrome, and dry skin may be seen.

Hand-foot syndrome presents as redness, swelling, peeling, and pain of the hands and feet, requiring symptomatic management.

2. Gastrointestinal Reactions

Stomatitis, dry mouth, diarrhea, vomiting, nausea, constipation, and abdominal pain are common.

Stomatitis may present as oral ulcers and affect eating.

Diarrhea and vomiting require attention to fluid replacement, and dose adjustment if necessary.

3. Systemic and Other Reactions

Fatigue, decreased appetite, weight loss, arthralgia, taste changes, and headache are common.

Eyelash changes, epistaxis, peripheral edema, and fever may occur.

Laboratory abnormalities include increased creatinine, elevated liver enzymes, increased lipase, decreased blood cell counts, and electrolyte disturbances.

4. Embryo-Fetal Toxicity

Based on animal studies and its mechanism of action, it can cause fetal harm or miscarriage.

Women of reproductive potential should have pregnancy status confirmed before treatment and use effective contraception during treatment and for 1 month after the last dose.

Male patients with female partners of reproductive potential should also use effective contraception during treatment and for 1 month after the last dose.