Mim8 for hemophilia

Last updated Oct. 31, 2025, by Andrea Lobo, PhD
Fact-checked by Joana Carvalho, PhD

What is Mim8 for hemophilia?

Mim8 (denecimig) is an antibody therapy being tested to prevent or reduce the frequency of bleeding episodes in people with hemophilia A, with or without neutralizing antibodies (inhibitors).

Hemophilia A is caused by mutations in the F8 gene that cause factor VIII (FVIII), a protein needed for the blood to clot, to be either missing or defective. Standard treatment includes factor replacement therapies, which provide patients with a functional version of FVIII. However, some patients may develop inhibitors against the provided clotting factor, which may limit the therapy’s efficacy.

Mim8’s active ingredient, denecimig, is a next-generation bispecific antibody designed to mimic the function of FVIII and stimulate the production of thrombin, an enzyme involved in blood clotting. Because Mim8 works without providing an external source of FVIII, it can be given to patients with inhibitors.

Administered via subcutaneous, or under-the-skin, injections in clinical trials, the prophylactic therapy is being developed by Novo Nordisk. The company submitted an application to the U.S. Food and Drug Administration (FDA) in late 2025 requesting Mim8’s approval for hemophilia A.

Therapy snapshot

How will Mim8 be administered in hemophilia?

In Phase 3 trials involving people with hemophilia A, Mim8 was administered via subcutaneous injections once weekly, once every two weeks, or once monthly. The treatment’s recommended regimen and dosing schedule, however, will not be known until it is granted regulatory approval.

Mim8 in hemophilia clinical trials

Mim8 was tested in people with hemophilia A in two Phase 3 trials that supported the submission of an application to the FDA requesting its approval.

• FRONTIER2 (NCT05053139) enrolled patients, 12 years and older, with or without inhibitors, who were randomly assigned to receive subcutaneous injections of Mim8 once weekly or once monthly, or continue their routine preventive or on-demand replacement therapy, for about six months. Results showed Mim8 was superior to on-demand or standard preventive therapies at reducing the frequency of bleeding episodes, regardless of inhibitor status.
• FRONTIER3 (NCT05306418) enrolled children, ages 1 to 11, with or without inhibitors, who received Mim8 weekly for approximately six months. After that, they could continue receiving treatment weekly or switch to the once-monthly regimen for another six months. Results similarly showed Mim8 safely and effectively controlled bleeds in children, irrespective of inhibitor status.

Participants who completed these trials or other studies of Mim8 could then enter an open-label extension study called FRONTIER4 (NCT05685238), which is assessing the therapy’s long-term safety and efficacy for up to 5.5 years.

Another open-label Phase 3 trial called FRONTIER5 (NCT05878938) assessed whether it is safe for patients on Hemlibra (emicizumab-kxwh), an approved prophylactic therapy for hemophilia A, to switch to Mim8. During the study, Mim8 was given using a prefilled pen injector and could be self-administered, with weekly, once every two weeks, and monthly dosing options. Results showed the switch was well tolerated in adults and adolescents with hemophilia A, regardless of whether they had inhibitors or not.

Mim8 side effects

Data are still limited about the safety profile of Mim8 for people with hemophilia A. Based on findings from an earlier Phase 2 trial, the most common side effects may include:

• allergic reactions
• injection site reactions.

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