Promedior announced that the Food and Drug Administration (FDA) has granted Orphan Drug designation for PRM-151 for the treatment of myelofibrosis. PRM-151 is a recombinant form of an endogenous human protein, pentraxin-2 (PTX-2) that acts as a monocyte/macrophage differentiation factor to prevent and potentially reverse fibrosis.

Earlier this year, Promedior announced Phase 2 results for PRM-151 in patients with myelofibrosis. The trial was a multicenter, two stage, adaptive design study to determine the efficacy and safety of PRM-151 as a single agent or added to a stable dose of ruxolitinib in patients with Primary Myelofibrosis (PMF), Post-Polycythemia Vera MF (post-PV MF), or Post-Essential Thrombocythemia MF (post-ET MF). Twenty-seven patients were enrolled in the first stage of the study; up to 80 additional patients will be enrolled in the second stage.

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Clinical data demonstrated improvements in four independent treatment groups of myelofibrosis patients who received PRM-151 weekly or monthly, either as a single agent or in patients with no further improvements on a stable dose of ruxolitinib. PRM-151 demonstrated a 50% reduction in symptoms according to the MPN-SAF Total Symptom Score in seven patients, five of which have persisted for ≥12 weeks and are therefore confirmed IWG-MRT Clinical Improvement symptom responses; five reductions in bone marrow fibrosis by ≥1 grade, with two of three patients confirmed 12 weeks later and two patients pending confirmatory biopsy; a ≥20% reduction in spleen volume reduction in five patients with one 50% reduction lasting eight weeks; and improvements in hemoglobin and platelets.

PRM-151 was previously designated Orphan Drug designation for the treatment of idiopathic pulmonary fibrosis.

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