Margarida Maia, PhD, —

An experimental therapy being developed by Omeros can nearly double the level of hemoglobin safely after three doses in severely anemic people with paroxysmal nocturnal hemoglobinuria (PNH). That’s according to interim data from an ongoing Phase 1b clinical trial that’s evaluating the effect of once-monthly subcutaneous (under-the-skin) injections of the therapy, called OMS906, in people with PNH who’ve never been treated with a complement inhibitor. “We are excited by the data resulting from this trial of treatment-naïve patients,” Gregory A. Demopulos, MD, Omeros’ chairman and CEO, said in a company press release. “The degree of hemoglobin improvement in such a severely anemic population is remarkable.” Company plans to increase number of trial participants and test higher doses. The company is planning to change testing from Phase 1b to Phase 2 to increase the number of participants, test higher doses, and prepare to meet with regulatory authorities to discuss a plan for getting the treatment approved. PNH is most often caused by certain mutations that cause blood cells to be erroneously primed for destruction. The complement system — a cascade of proteins that work with the immune system to protect the body against infection — is called into action and set against blood cells. Patients with PNH often develop anemia, which happens when red blood cells are destroyed and there is a shortage of these cells in the bloodstream. One way to check for anemia is by measuring the amount of hemoglobin in the blood. Hemoglobin is the protein in red blood cells that carries oxygen. Approved medications for PNH all work by blocking steps in the activation of the complement system. As a result, people who take these medications may be at an increased risk of developing an infection. Unlike these medications, OMS906 does not block the part of the complement system that helps protect the body against infections. Instead, it blocks the so-called alternative complement pathway by targeting a protein called MASP-3. This protein is found at a low level in the bloodstream and has a slow turnover, which means that older proteins aren’t replaced as quickly by new ones. This should allow OMS906 to keep working against its target for a long time. Increase in hemoglobin level was rapid and consistent over time. The nine people with PNH who’ve entered the trial so far have all received the lowest dose of OMS906 being tested; among them, seven received two or more doses, four got three or more doses, and three have received four doses. Besides PNH, some participants also had low blood iron, myelodysplastic syndrome (a type of blood cancer), or chronic kidney failure. At the time of study entry (baseline), participants’ mean hemoglobin level was at 6.78 g/dL. After two doses, hemoglobin levels increased significantly by a mean of 4.75 g/dL. By day 85 — after three doses of OMS906 — mean hemoglobin level was at 12.4 g/dL, which was nearly double of that seen at baseline. The increase in hemoglobin level was rapid and consistent over time. The mean level of lactate dehydrogenase, a marker of cell damage, was nearly eight times the upper limit of normal at baseline. Eight days after the first dose of OMS906, its level began to drop and was further reduced over time. None of the patients needed or received blood transfusions during the trial. Trial data 'quite impressive' “These trial data are quite impressive,” said Eleni Gavriilaki, MD, PhD, an assistant professor of hematology at Aristotle University of Thessaloniki, in Greece. Based on data from healthy individuals in a Phase 1 clinical trial and people with PNH, the company determined that OMS906 may be given less frequently, once every three months, either by subcutaneous or intravenous (into-the-vein) injection. “Achievement of once-quarterly dosing would be well received by physicians and their patients, representing a paradigm shift in the treatment of PNH and other alternative pathway disorders,” Gavriilaki said. Omeros also is testing OMS906 in people with PNH who did not respond well to Ultomiris (ravulizumab), an approved medication for PNH that’s marketed by AstraZeneca. Preliminary data from this trial is expected later this year. “The results observed to date demonstrate that OMS906 provides clinically effective inhibition of the alternative pathway, opening for the drug the wide range of alternative pathway-related diseases, a good number of which already have been clinically validated by agents on the market or in development,” Demopulos said.

Margarida Maia, PhD, —

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