On May 31, 2017, FDA approved Rebinyn, Novo Nordisk’s longer-acting GlycoPEGylated recombinant factor IX product. It is indicated for on-demand treatment and control of bleeding episodes and for perioperative (before, during and after surgery) management of bleeding. Rebinyn has polyethylene glycol (PEG) polymer chains attached to the carbohydrate (glyco) side chains of the factor IX molecule to give it a lifetime in the bloodstream approximately five times longer than normal factor IX. Rebinyn also appears to maintain higher factor IX levels between infusions.
Note that Rebinyn was not approved for prophylaxis, although its European approval (it’s called Refixia in Europe) did include a prophylaxis indication. This may be a reflection of concern about the unknown effect of PEG over time in the body. Although there are currently several PEG-containing drugs on the market, most of them are not taken chronically over a long period of time as Rebinyn would be for prophylaxis. Presumably, Novo Nordisk will do further studies to try to demonstrate the safety of the product in prophylaxis, since the longer half-life and higher factor IX levels would be real benefits in that scenario. Novo plans to introduce the product in the U.S. market in the first half of 2018.