Regeneron Pharmaceuticals has reported positive results from an ongoing Phase II clinical trial of pozelimab (REGN3918) in patients with paroxysmal nocturnal hemoglobinuria (PNH), a rare blood disorder.

Pozelimab is a monoclonal antibody inhibiting the pathway associated with haemolysis of red blood cells. The drug is intended to decrease LDH levels and the incidence of breakthrough haemolysis.

The open-label, single-arm, two-part Phase II study involved active symptomatic PNH patients. It assessed an 800mg weekly subcutaneous dose of the drug, followed by an initial intravenous loading dose.

Top-line data showed that the drug decreased the haemolysis. All six participants in the initial cohort had normal levels of lactate dehydrogenase (LDH), a blood biomarker of high haemolysis, at week eight.

The adverse events (AEs) experienced by the participants were not serious or had not resulted in discontinuation. Three patients had treatment-related AEs at the analyses cut-off date, including headache, injection site reaction, and nausea.

Regeneron Pharmaceuticals president and chief scientific officer George Yancopoulos said: “In our view, any new medicine for PNH must deliver real change for patients, such as more patients achieving normal LDH levels, or a reduced treatment burden that potentially allows for at-home self-administration.

“We are encouraged by these early pozelimab results, with patients achieving normal levels of LDH by week eight using the subcutaneous dosing regimen. We look forward to speaking with regulators about the next phase of our program for these patients.”

Regeneron said that the Phase II trial data could support an orphan disease indication for pozelimab. The company has commenced the second part of the trial and is planning for a Phase III programme.