Interim results of a phase 3 study suggest favorable efficacy, immunogenicity, and safety of rurioctocog alfa pegol for the treatment of severe hemophilia A, according to an article published in the Expert Review of Hematology.

The researchers recruited patients with severe hemophilia A who had previously not been treated or with a maximum exposure of 2 days prior to screening. Of 80 patients, 59 (73.8%) received at least 1 dose of rurioctocog alfa pegol, 54 received prophylaxis, and 35 received on-demand treatment.

The primary endpoint was the incidence of factor VIII (FVIII) inhibitor development. The researchers conducted the interim analysis after 50 patients had completed at least 50 exposure days without developing FVIII inhibitors or had developed a confirmed inhibitor at any time.

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According to the results, the incidence of inhibitor development was 0.19 (10/52). The total annualized bleeding rate was 3.2 (2.0-5.0) for those who received prophylaxis and 3.2 (1.6-6.3) for patients receiving treatment on demand.

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At least 1 dose of the experimental drug was given to 5 patients for immune tolerance induction and it yielded favorable results in 1 of them. Moreover, the hemostatic efficacy of most bleedings was regarded as “excellent” or “good” after 24 hours and at resolution.

Treatment-related adverse events were reported in 13 patients, including 10 cases of FVIII inhibitor development.

“No thromboembolic adverse events were reported, and no patients experienced drug hypersensitivity when treated with rurioctocog alfa pegol for immune tolerance induction, even when the high-dose regimen was used. These data indicate that rurioctocog alfa pegol has a safety and efficacy profile in previously untreated patients consistent with that reported in previously treated pediatric, adolescent, and adult patients with hemophilia A for the treatment and prevention of bleeds,” Sidonio and colleagues wrote.

Development of FVIII inhibitors occurs in approximately 20% to 35% of previously untreated patients with severe hemophilia A, which might interfere with the effectiveness of FVIII concentrate treatment.


Sidonio RF Jr, Thompson AA, Peyvandi F, et al. Immunogenicity, safety, and efficacy of rurioctocog alfa pegol in previously untreated patients with severe hemophilia A: interim results from a phase 3, prospective, multicenter, open-label study. Expert Rev Hematol. Published online September 7, 2023. doi:10.1080/17474086.2023.2247160