Pacritinib is a JAK2/FLT3 inhibitor used for the treatment of splenomegaly or symptoms associated with myelofibrosis.

I. Patient Assessment Before Treatment

1. Platelet Count Assessment

(1) Baseline platelet levels must be measured before treatment.

(2) Although pacritinib can be used in patients with low platelet counts, clinical studies have shown that thrombocytopenia and fatal bleeding events (including intracranial hemorrhage) pose serious safety risks.

(3) Extreme caution is required when using this drug in patients with severely low platelet counts.

2. Cardiac Function Assessment

(1) An electrocardiogram should be performed at baseline to assess the QT interval.

(2) QTc prolongation has been observed, and patients with a history of heart failure or arrhythmias are at higher risk.

3. Liver and Kidney Function Testing

(1) Liver and kidney function should be tested before treatment.

(2) Patients with renal impairment have increased drug exposure and require close monitoring.

4. Bleeding Risk Assessment

Due to reports of serious bleeding events such as subdural hematoma and intracranial hemorrhage, concomitant use of anticoagulants or antiplatelet agents should be assessed before treatment.

II. Monitoring and Risk Management During Treatment

1. Hematologic Monitoring

(1) Regular monitoring of complete blood count should be performed during treatment.

(2) If severe hematologic toxicity occurs, dose adjustment or treatment interruption should be considered.

2. Bleeding Event Monitoring

(1) Watch for any signs of abnormal bleeding, including bruising, nosebleeds, gum bleeding, black stools, etc.

(2) If active bleeding occurs, the drug should be discontinued immediately.

3. Management of Gastrointestinal Adverse Reactions

(1) Diarrhea, nausea, and vomiting are the most common adverse reactions.

(2) Patients are advised to maintain adequate hydration during treatment and to contact a doctor if severe diarrhea occurs.

4. Cardiac Toxicity Monitoring

If new symptoms such as difficulty breathing, lower extremity edema, palpitations, or chest pain occur during treatment, immediate medical evaluation is required.

5. Infection Monitoring

If signs of infection such as fever, cough, or chills occur during treatment, prompt evaluation is necessary.

III. Contraindicated Populations and Drug Interactions

1. Pregnancy and Breastfeeding

(1) Pacritinib has shown embryotoxicity and teratogenicity in animal studies and is contraindicated during pregnancy.

(2) Women of childbearing potential should use effective contraception during treatment and after discontinuation.

2. CYP3A4 Interactions

(1) Pacritinib is primarily metabolized by CYP3A4.

(2) Avoid concomitant use with strong CYP3A4 inhibitors or inducers.

3. Elderly Patients

The incidence of adverse reactions in elderly patients is higher than in younger patients, and enhanced monitoring is required.

4. Prior JAK Inhibitor Treatment History

Data on the safety and efficacy of switching from other JAK inhibitors to pacritinib are lacking.