Esperoct (turoctocog alfa pegol) is an approved treatment for hemophilia A developed by Novo Nordisk. Esperoct can be used as a preventive, or prophylactic, treatment to help prevent bleeding, or as an on-demand treatment to help stop a bleeding episode.

Esperoct is approved for use in adults and children in the U.S., and Canada, and for adults and teenagers age 12 and older in the EU.

How does Esperoct work?

Hemophilia A is a rare genetic disorder in which the body does not produce enough or produces mutated forms of a protein called factor VIII, which is needed for blood to clot.

Esperoct is a modified glyco-PEGylated factor VIII protein, in which the B-domain (a region within the protein) is missing. This enables this special factor VIII protein to be broken down more slowly and remain in the body for longer periods of time to help protect against bleeding — meaning it has an extended half-life, and typically dosing is needed less frequently.

The activation of the blood-clotting pathway results in the removal of the PEG molecule, generating recombinant factor VIII similar in structure to natural factor VIII.

Esperoct in clinical trials

Esperoct was evaluated in a Phase 1 dose-escalation and safety trial (NCT01205724), called Pathfinder 1, in 26 people with severe hemophilia A. Participants received one of three doses (25, 50, or 75 IU per kg) of Esperoct. Its pharmacokinetics (movement within the body) was a primary assessment.

Trial results showed the treatment was well-tolerated at all doses, and no participants developed inhibitors against it. The mean terminal half-life of the factor concentrate was 19 hours, representing a 1.6-fold prolongation in comparison to the FVIII products previously used.

A Phase 3 multinational and open-label trial (NCT01480180), called Pathfinder 2, evaluated the safety, pharmacokinetics, and effectiveness of Esperoct used as a prophylaxis and to treat episodic bleeds in 186 people with severe hemophilia A, ages 12 and above.

The results of this trial were published in the Journal of Thrombosis and Haemostasis. Most of those enrolled, 175 people, were given Esperoct as a prophylaxis (50 IU/kg of bodyweight) every fourth day. Their median annual bleed rate (the number of bleeds a person experiences over one year) was 1.33, and 70 patients (40% of all enrolled) had no bleeds during the trial. Bleeding episodes were treated at doses ranging from 20 to 75 IU/kg, and, overall, 84% of these episodes resolved after a single infusion of Esperoct and 95.5% with two infusions. The treatment was generally well-tolerated. One person tested positive for anti-FVIII inhibitors after 93 exposure days to Esperoct, and withdrew from the study.

Another Phase 3 trial (NCT01731600), called Pathfinder 5, evaluated the safety, pharmacokinetics, and effectiveness of Esperoct used as prophylaxis in children younger than 12 years with severe hemophilia A. Patients received twice-weekly intravenous injections of Esperoct for prophylaxis, and were also given doses to treat bleeding episodes.

Findings in its Phase 3 studies showed that Esperoct had a 1.6-fold better half-life in adults and adolescents, and a 1.9-times longer half-life in children, compared to standard factor VIII products.

Pathfinder 2 and Pathfinder 5 study results were also addressed in an article, published in the journal Patient Preference and Adherence, that investigated how treatment affected patients’ health-related quality of life (HRQoL) and overall treatment satisfaction (TS). It found Esperoct’s use improved HRQoL and TS in children, adolescents, and adults.

Pathfinder 3, another Phase 3 trial (NCT01489111), looked at Esperoct’s effectiveness during surgical procedures in adolescents and adults with hemophilia A, including joint replacements. Patients were given intravenous injections of Esperoct before, during, and after surgery to help with bleeding.

The results of the Pathfinder 2, Pathfinder 3, and Pathfinder 5 trials were summarized in an article published in the journal Blood in 2019. These results showed that Esperoct was effective as a prophylactic agent, with bleeds “generally” being controlled with a single dose, and effective as a treatment during bleeding episodes in both adults and children.


Last updated: Feb. 12, 2020


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