PRM-151: Preliminary Phase II data

Preliminary data from 27 patients with primary MF and post polycythemia vera/essential thrombocythemia MF (PPV-MF/PET-MF) in the first stage of a 2-stage, open-label, North American Phase II trial showed that once-weekly or once-monthly 10 mg/kg IV PRM-151 with or without a stable dose of ruxolitinib led to a 50% reduction in symptoms as measured by MPN-SAF total symptom score, a secondary endpoint, in 7 patients. Of those 7 patients, 5 responses have persisted for >=12 weeks and Promedior said are therefore considered confirmed IWG-MRT clinical improvement symptom responses. Additionally, PRM-151 led to reductions in bone marrow fibrosis of >=1 grade in 5 patients. The company said all treatment groups met the pre-specified efficacy criteria for proceeding to the second stage of the trial, which will enroll up to an additional 80 patients.

Weekly and monthly dosing of PRM-151 were both well tolerated alone and in combination with ruxolitinib, with no evidence of myelosuppression observed. Serious adverse events included pneumonia, progressive multi-organ failure, abdominal pain, bone marrow biopsy site hematoma, sialadenitis, gastroenteritis and respiratory syncytial virus. Promedior said 15 of the 18 patients who completed the 24-week first stage of the trial are continuing treatment in a study extension. Data were presented at the American Society of Clinical Oncology meeting in Chicago. Complete data from the first stage of the trial are expected by year end. PRM-151 is also in a Phase Ib trial to treat idiopathic pulmonary fibrosis (IPF), for which the product has Orphan Drug designation in the U.S. and EU. ...