Pacritinib: Additional Ph III PERSIST-2 data

Additional data from 221 patients with myelofibrosis and platelet counts <100,000/µL in the intent-to-treat (ITT) population of the open-label, international Phase III PERSIST-2 trial showed that oral pacritinib given as 200 mg twice daily or 400 mg once daily led to a ≥35% reduction in spleen volume from baseline to week 24, a co-primary endpoint, in 18% of patients vs. 3% of patients receiving investigator’s choice of best available therapy, including Jakafi ruxolitinib (p=0.001). Pacritinib also led to a total symptom score reduction of ≥50% per the modified MPN-SAF 2.0 diary from baseline to week 24, a co-primary endpoint, in 25% of patients vs. 14% of patients receiving best available therapy (p=0.079). The co-primary endpoints compared pooled data for both dosing regimens of pacritinib to the control group.

On secondary endpoints, the 200 and 400 mg doses of pacritinib led to a ≥35% reduction in spleen volume from baseline to week 24 in 22% and 15% of patients, respectively, vs. 3% of patients receiving best available therapy (p=0.001 and p=0.017, respectively). The 200 and 400 mg doses also led to a total symptom score reduction of ≥50% from baseline to week 24 in 32% and 17% of patients vs. 14% for best available therapy (p=0.011 and p=0.652, respectively). Data were presented at the American Society of Hematology meeting in San Diego. CTI previously reported that pacritinib met the spleen volume endpoint, but missed the total symptom score endpoint (see BioCentury, Sept. 5, 2016). The company said the secondary endpoints could not be "evaluated formally" due to the trial missing 1 of the co-primary endpoints...