that the U.S. Food and Drug Administration (FDA) has granted Fast Track designation to PRM-151 for the treatment of primary myelofibrosis, post-polycythemia vera myelofibrosis, and post-essential thrombocythemia myelofibrosis.
Myelofibrosis is a rare hematologic cancer that affects approximately 18,000 Americans per year. At present, the only approved orphan drug for myelofibrosis is Jakafi (ruxolitinib) and the only potential ‘curative’ treatment is allogeneic bone marrow transplant. Average survival time for patients with myelofibrosis is 5 years.
In June, preliminary data from a phase 2 study of PRM-151 was presented
at American Society for Clinical Oncology (ASCO) 2014 Annual Meeting. In that presentation, data from 18 patients with myelofibrosis who had completed 24 weeks of therapy was shown. In the ASCO presentation, PRM-151 demonstrated a 50% reduction in symptoms according to the MPN-SAF Total Symptom Score in 7 patients, 5 of which have persisted for ≥12 weeks and are therefore confirmed IWG-MRT Clinical Improvement symptom responses; 5 reductions in bone marrow fibrosis by ≥1 grade, with 2 of 3 patients confirmed 12 weeks later and 2 patients pending confirmatory biopsy; a ≥20% reduction in spleen volume reduction in 5 patients with one 50% reduction lasting 8 weeks; and improvements in hemoglobin and platelets. Also 15 out of 18 patients who have completed the 24 week study are continuing treatment in a study extension.
From a safety perspective, most adverse events observed in the study were Grade 1 or 2 and considered unrelated to PRM-151. Overall, there were 14 severe adverse events in 5 study patients, including 3 deaths, 2 from pneumonia and 1 from progressive multi-organ failure. Other severe adverse events were abdominal pain, bone marrow biopsy site hematoma, sialadenitis, gastroenteritis and respiratory syncytial virus.
The phase 2 trial is a multi-center, 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, post-polycythemia vera myelofibrosis, or post-essential thrombocythemia myelofibrosis. The first stage has 27 patients enrolled and the second stage expects to have 80 additional patients.
The Fast Track designation allows the company to expedite the review of new drugs that are intended to treat serious or life-threatening conditions, such as myelofibrosis. PRM-151 was given orphan drug designation in September 2014.
Beth Tréhu, MD, FACP, Chief Medical Officer of Promedior said:
“We are extremely pleased to have received Fast Track designation for PRM-151 as we believe that PRM-151 offers the potential to better meet the needs of patients with myelofibrosis."
“This designation validates our perspective that there is a clear and compelling need for a novel mechanism for the treatment of myelofibrosis that specifically targets the underlying fibrotic processes of the disease. We will continue to work expeditiously to advance this program through the clinic and look forward to presenting the full data set from the first stage of our Phase 2 study later this year.”