Pacritinib (Vonjo) — Clinical FAQs

Q: How does Pacritinib work (mechanism of action)?

Inhibitor of JAK2, IRAK1 (interleukin-1 receptor-associated kinase 1), and CSF1R. Lacks significant JAK1 inhibition (unlike ruxolitinib), thereby causing less off-target thrombocytopenia from JAK1 pathways, enabling use in patients with severe baseline thrombocytopenia. IRAK1 inhibition may contribute to additional anti-inflammatory activity in the myelofibrosis microenvironment.

Q: How is Pacritinib administered?

Pacritinib is administered Oral (PO). Administer 200 mg orally twice daily (BID) with or without food.

Q: What are the most common side effects of Pacritinib?

The most commonly reported side effects of Pacritinib (≥10% incidence) include: Diarrhea (51% — most common), Nausea (26%), Thrombocytopenia (22%), Peripheral edema (17%), Vomiting (16%) and others (8 total). Consult your oncologist for complete prescribing information.

Q: Does Pacritinib have a black box warning?

Yes. Pacritinib carries FDA black box warning(s) regarding: 1. Fatal and serious cardiac and hemorrhagic events: Increased rates of Grade 3 or higher cardiac failure, atrial fibrillation, and hemorrhagic events were observed in myelofibrosis clinical trials with pacritinib.

Q: Is Pacritinib safe during pregnancy?

Pacritinib pregnancy safety: Category D equivalent — can cause fetal harm; effective contraception required during and for at least 2 weeks after last dose.. Oncologists should review the complete prescribing information and discuss reproductive risks with patients before initiating therapy.

Question 1

What is Pacritinib FDA-approved to treat?

Accepted Answer

Pacritinib is FDA-approved for the following oncology indications: 1. Intermediate- or high-risk primary or secondary (post-PV or post-ET) myelofibrosis in adults with platelet counts below 50×10⁹/L (FDA accelerated approval February 2022; PERSIST-2: improved spleen volume response and total symptom score vs best available therapy including hydroxyurea in patients with platelets <100×10⁹/L).

Question 2

How does Pacritinib work (mechanism of action)?

Accepted Answer

Inhibitor of JAK2, IRAK1 (interleukin-1 receptor-associated kinase 1), and CSF1R. Lacks significant JAK1 inhibition (unlike ruxolitinib), thereby causing less off-target thrombocytopenia from JAK1 pathways, enabling use in patients with severe baseline thrombocytopenia. IRAK1 inhibition may contribute to additional anti-inflammatory activity in the myelofibrosis microenvironment.

Question 3

How is Pacritinib administered?

Accepted Answer

Pacritinib is administered Oral (PO). Administer 200 mg orally twice daily (BID) with or without food.

Question 4

What are the most common side effects of Pacritinib?

Accepted Answer

The most commonly reported side effects of Pacritinib (≥10% incidence) include: Diarrhea (51% — most common), Nausea (26%), Thrombocytopenia (22%), Peripheral edema (17%), Vomiting (16%) and others (8 total). Consult your oncologist for complete prescribing information.

Question 5

Does Pacritinib have a black box warning?

Accepted Answer

Yes. Pacritinib carries FDA black box warning(s) regarding: 1. Fatal and serious cardiac and hemorrhagic events: Increased rates of Grade 3 or higher cardiac failure, atrial fibrillation, and hemorrhagic events were observed in myelofibrosis clinical trials with pacritinib.

Question 6

Is Pacritinib safe during pregnancy?

Accepted Answer

Pacritinib pregnancy safety: Category D equivalent — can cause fetal harm; effective contraception required during and for at least 2 weeks after last dose.. Oncologists should review the complete prescribing information and discuss reproductive risks with patients before initiating therapy.

Pacritinib — Drug Monograph

Mechanism of Action

FDA Indications

Common Side Effects

Clinical Pearl

Related Therapies & Mechanisms