There has been a number of clinical studies on one of the newer drugs on the market for hemophilia A: efmoroctocog alfa. It has generated excitement among the medical community because it is not a traditional intravenous (IV) replacement therapy; instead, it is a prophylactic medication and has a longer half-life than conventional factor VIII (FVIII) preparations, meaning that less frequent injections are required. 

Certainly, the prospect of a prophylactic medication for hemophilia A is deeply encouraging. It has the potential to break the cycle that patients with severe hemophilia face—going from bleeding crisis to bleeding crisis. Now scientists are racing to conduct studies to better understand just how effective this drug is. 

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James E. Frampton, a New Zealand researcher, has conducted a review of the uses of efmoroctocog alfa in hemophilia A. We will review his work to examine how this drug works, as well as explore the evidence on how effective it is as a prophylactic hemophilia A drug. 

A Step Forward 

One of the signs that medical progress has not stagnated is the introduction of newer drugs with a different mechanism of action than the ones currently available. The drug efmoroctocog alfa certainly fits the bill, and in a broader sense shows that research devoted to hemophilia A research is yielding results. 

It should be noted that FVIII replacement therapy remains the mainstay of treatment for hemophilia A. However, prophylaxis has an incredibly important role to play in treating hemophilia A. Frampton raised 2 main points on what we hope prophylactic medication in hemophilia A can achieve: preserve joint health and reduce the formation of FVIII inhibitors (one of the most serious complications of FVIII replacement therapy). 

“Efmoroctocog alfa, a first-in-class rFCVII-Fc fusion protein consisting of a single molecule of recombinant B-dominant deleted human FVIII covalently linked to the dimeric Fc domain of human immunoglobulin GI, is one such extended half-life rFVIII preparation,” Frampton wrote on the technical properties of this drug. Importantly, it is approved for use in the USA, the EU, and Japan.

Promising Clinical Trial Results

So how well does it work? Frampton quoted 2 studies on the use of efmoroctocog alfa in previously treated patients with severe hemophilia A. One trial involved adults and adolescent males aged 12 or more years, and another trial involved children aged less than 12 years. Data revealed that efmoroctocog alfa was able to achieve low bleeding rates, improve joint health, and improve health-related quality of life in previously treated patients with severe hemophilia A. None of the patients developed a neutralizing antibody to FVIII during the studies.

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What about medication adherence? It is well and good that a drug shows promise; whether patients consent to take it as prescribed is quite another matter. This is the subject of a clinical trial conducted by Pitance et al. 

Pitance and colleagues wanted to assess medical adherence to efmoroctocog alfa. They first placed participants on standard FVIII prophylaxis for 12 months, then switched them to efmoroctocog alfa, which has a longer half-life. This meant a decrease in the mean number of weekly prophylactic injections. 

The results indicated that adherence after (and before) the switch in medication were high; there was a trend towards greater medication adherence after the switch, although not enough to be statistically significant. 

At the very least, the findings of this study indicate that medication adherence holds steady when patients are switched from a standard half-life prophylactic medication to the longer half-life efmoroctocog alfa. 

Another benefit of efmoroctocog alfa highlighted by Frampton is that it reduces the cost of health care in the long term. He wrote, “In practice, FVIII product choice may be influenced not only by pharmacokinetic differences and patient preference, but also by cost.” 

How does efmoroctocog alfa reduce cost in the long run? The main reason is its ability to reduce the formation of FVIII inhibitors. Hemophilia A treatment, at present, requires lifelong administration. The reduced formation of FVIII inhibitors means hemophilia A patients can potentially experience lifelong therapy without the added burden of developing FVIII inhibitors. This means treatment is more efficient and fewer complications can be expected. 

Long-Term Benefit Seen 

We have seen in this article that efmoroctocog alfa offers substantial benefits compared to traditional hemophilia therapy. Evidence suggests that its prophylactic properties are indeed present and working, offering long-term clinical benefit to the patient.

As more studies are conducted, no doubt we will have a fuller appreciation of the merits and limitations of this drug. As for now, Frampton wrote, “In conclusion, efmoroctocog alfa is an established and effective extended-half life FVIII replacement therapy for the management of hemophilia A.” 


Frampton JE. Efmoroctocog alfa: a review in haemophilia A. Drugs. 2021;81(17):2035-2046. doi:10.1007/s40265-021-01615-w

Pitance V, Désage S, Lienhart A, Meunier S, Chamouard V. Haemophilia A patients’ medication adherence to prophylaxis with efmoroctocog alfa. Haemophilia. 2021;27(3):e368-e375. doi:10.1111/hae.14301