Pacritinib Improves Spleen Volume and Symptoms in Myelofibrosis


Ashwin Kishtagari, MD, discusses the PERSIST-2 trial of pacritinib for patients with primary myelofibrosis and low platelet counts.

Ashwin Kishtagari, MD, assistant professor of medicine at Vanderbilt University Medical Center, discusses the PERSIST-2 trial (NCT02055781) of pacritinib (Vonjo) for patients with primary myelofibrosis and low platelet counts.

The phase 3 PERSIST-2 trial, which led to the approval of pacritinib, differs from the PERSIST-1 trial (NCT01773187) because patients had not received prior JAK (Janus kinase) inhibitor in the first trial. In PERSIST-2, patients could have received a prior JAK inhibitor including ruxolitinib (Jakafi) and had a platelet count of 100,000/µL or lower. Patients were randomly assigned to 3 arms including pacritinib at 400 mg once daily, pacritinib 200 mg twice daily, and best available therapy (BAT) which could include ruxolitinib.

The spleen volume reduction with pacritinib in patients with baseline platelets below 50,000/µL was 29% versus 3% for BAT. In terms of symptom improvement, a pooled analysis of the PERSIST-1 and PERSIST-2 populations found a total symptom score improvement of 50% or better at week 24 in 26% of those receiving pacritinib versus only 9% who received BAT. Based on these findings, the FDA approved pacritinib for patients with platelet count below 50,000/µL.


0:08 | PERSIST-2, which actually led to the FDA approval of this medication is also a randomized study, but here they put patients who already were exposed to JAK inhibitors, so [it was] a relapsed/refractory patient population. The treatment arms [were] pacritinib 400 mg once a day, 200 mg twice a day, as well as the BAT, which could include patients who are on ruxolitinib.

0:42 | The most important response they had was the spleen volume response, which is an important mark for drug approval in myelofibrosis. In the treatment arm, 29% had a spleen volume reduction of 35% compared [with] BAT of 3%. Then looking at the total symptom score, this is one of the main indications why we initiate treatment for this patient population. The treatment arm had a 26% reduction in symptom score at week 24 compared [with] 9% in the BAT arm. With these fantastic findings, pacritinib received FDA approval in patients with platelet count less than 50,000/µL.

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