Novo Nordisk’s Mim8 shows promising efficacy and safety in haemophilia A children, phase 3 interim results reveal

Novo Nordisk A/S has announced encouraging interim results from its phase 3 FRONTIER3 clinical trial, highlighting the potential of its investigational drug, Mim8, as a game-changing treatment for children living with haemophilia A, both with and without inhibitors. The data, presented at the 18th Annual Congress of the European Association for Haemophilia and Allied Disorders (EAHAD 2025) in Milan, Italy, demonstrated that 74.3% of children receiving once-weekly Mim8 prophylaxis treatment experienced zero treated bleeds, showcasing a promising advance in managing this rare bleeding disorder.

Mim8, a Factor VIIIa (FVIIIa) mimetic bispecific antibody, is designed to restore haemostasis through subcutaneous administration, offering the potential for flexible dosing regimens, including once-weekly, bi-weekly, or once-monthly schedules. Although Mim8 is still investigational and not yet approved by regulatory authorities, these interim results suggest it could significantly improve the lives of children with haemophilia A, a condition that affects over one million people worldwide.

What is Mim8 and how does it work in haemophilia A treatment?

Mim8 is an innovative drug designed to mimic the function of the missing or defective Factor VIII protein in individuals with haemophilia A, a genetic disorder that impairs the body’s ability to form blood clots. The drug functions as a bispecific antibody that bridges Factor IXa and Factor X, effectively replacing Factor VIII’s role in the clotting process. This mechanism helps restore the body’s thrombin generation capacity, enabling more effective blood clot formation and reducing the risk of spontaneous or prolonged bleeding episodes.

Administered under the skin, Mim8 aims to provide sustained protection against bleeds with the convenience of less frequent dosing. This is particularly beneficial for young children, as traditional haemophilia treatments often require multiple intravenous infusions per week, which can be both physically and emotionally challenging for patients and their families.

How effective is once-weekly Mim8 in reducing bleeds in children?

The phase 3 FRONTIER3 trial enrolled 70 children aged 1 to 11 years, including 14 with haemophilia A and inhibitors and 56 without inhibitors. During the first part of the study, all participants received once-weekly Mim8 prophylaxis treatment for 26 weeks. The interim results revealed that the mean annualised bleeding rate (ABR) for treated bleeds was just 0.53, while the median ABR was zero. Remarkably, 74.3% of participants experienced zero treated bleeds, and all children with inhibitors reported no treated bleeds during the study period.

Following the initial 26 weeks, participants had the option to either continue with the weekly dosing schedule or switch to once-monthly Mim8. Approximately 45% chose the once-monthly regimen, while 55% remained on weekly dosing, reflecting the flexibility and convenience that Mim8 offers based on individual preferences and lifestyles.

What do safety data from the FRONTIER3 trial reveal about Mim8?

Safety is a paramount concern in the development of new therapies, particularly for paediatric populations. The FRONTIER3 trial reported no major safety concerns associated with Mim8 prophylaxis treatment. There were no deaths, thromboembolic events, or severe treatment-related adverse events observed during the study. Additionally, there was no clinical evidence of neutralising anti-drug antibodies (ADAs), which can sometimes reduce the effectiveness of biologic treatments.

Injection site reactions were minimal, occurring in less than 1% of all injections, and were generally mild. This favourable safety profile aligns with previous trials evaluating Mim8, suggesting consistent results across different study populations.

Professor Johnny Mahlangu, lead investigator and Director of the Haemophilia Comprehensive Care Centre at Charlotte Maxeke Johannesburg Hospital in South Africa, emphasised the significance of these findings. He noted that managing haemophilia A in children requires a delicate balance of effective treatment, minimal disruption to daily life, and support for emotional and social well-being. According to Mahlangu, the data indicate that Mim8 could offer an efficacious and flexible dosing option, potentially reducing the treatment burden on families.

How does Mim8 improve the quality of life for children and caregivers?

Beyond clinical efficacy, the FRONTIER3 trial also evaluated patient- and caregiver-reported outcomes, offering valuable insights into how Mim8 prophylaxis treatment impacts daily life. The results were overwhelmingly positive. At the 26-week mark, 98% of caregivers expressed a preference for Mim8 over previous treatments, with 73% stating they ‘very strongly’ preferred it.

Caregivers reported that Mim8 significantly reduced the treatment burden, improved physical function, and enhanced the overall quality of life for their children. Improvements were observed in physical activity levels, such as running and playing, which are often limited in children with haemophilia due to the risk of bleeding. Additionally, positive trends were noted in quality of life scores compared to baseline, highlighting the potential for Mim8 to support both physical health and emotional well-being.

Ludovic Helfgott, executive vice president for Rare Disease at Novo Nordisk, highlighted the company’s commitment to addressing the unmet needs of the rare bleeding disorders community. He stated that Mim8 is designed to offer flexibility in treatment, enabling families to choose dosing schedules that best fit their lifestyles without compromising safety or efficacy. Helfgott added that the strong preference for Mim8 among caregivers reflects its potential to transform haemophilia care.

What’s next for Mim8 in the regulatory process?

Novo Nordisk plans to submit Mim8 for regulatory approval in 2025, marking an important milestone in the drug’s development. The company will continue to present data from the ongoing phase 3 FRONTIER clinical programme, which includes additional studies such as FRONTIER2, FRONTIER4, and FRONTIER5. These studies will provide further insights into Mim8’s long-term efficacy, safety, and patient-reported outcomes.

As more data emerge, Novo Nordisk aims to solidify Mim8’s role as a potential new standard of care for haemophilia A in children. If approved, Mim8 could offer a revolutionary approach to managing this rare disorder, providing effective bleed prevention with greater convenience and flexibility than current treatment options.