The US Food and Drug Administration (FDA) has granted accelerated approval to Vonjo (pacritinib) for the treatment of adults with intermediate or high-risk primary or secondary (post-polycythemia vera or post-essential thrombocythemia) myelofibrosis with a platelet count below 50×109/L.

Vonjo is an oral kinase inhibitor with activity against wild-type JAK2, JAK2V617F, and FLT3. Myelofibrosis is often associated with dysregulated JAK2 signaling.

The approval was based on data from the randomized, controlled, phase 3 PERSIST-2 trial ( Identifier: NCT02055781), which evaluated the efficacy and safety of pacritinib in adults with thrombocytopenia and primary or secondary myelofibrosis. Patients were randomly assigned 1:1:1 to receive pacritinib at 400 mg orally once daily (n=104), 200 mg twice daily (n=107), or best available therapy (BAT; n=100). 

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Among 31 evaluable patients who received pacritinib at 200 mg twice daily and had a platelet count less than 50×109/L, 29% (95% CI, 14.2-48.0) of patients achieved a reduction in spleen volume of at least 35% at week 24 (as measured by MRI or CT) vs 3.1% (95% CI, 0.1-16.2) of those treated with BAT (most common agents included ruxolitinib, watchful waiting, and hydroxyurea).

The median reduction in spleen volume for patients with a platelet count less than 50×109/L was 27.3% for patients treated with pacritinib at 200 mg twice daily compared with 0.9% for those treated with BAT.

The most common adverse reactions reported with pacritinib were diarrhea, thrombocytopenia, nausea, anemia, and peripheral edema. The benefits and risks of treatment should be discussed with patients as another JAK inhibitor was shown to increase the risk for major adverse cardiac events, thrombosis, secondary malignancies, and serious infections.

Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory clinical trial. To fulfill the post-approval requirement, CTI BioPharma Corp. expects to complete its confirmatory PACIFICA trial ( Identifier: NCT03165734), with results expected by mid-2025.

Vonjo is supplied as 100 mg capsules in 120-count bottles.


  1. CTI BioPharma announces FDA accelerated approval of Vonjo (pacritinib) for the treatment of adult patients with myelofibrosis and thrombocytopenia. News release. CTI BioPharma Corp. February 28, 2022. Accessed March 1, 2022.
  2. Vonjo. Package insert. CTI BioPharma Corp.; 2022. Accessed March 1, 2022.

This article originally appeared on MPR