The following article features coverage from the 61st American Society of Hematology Annual Meeting and Exposition. Click here to read more of Hematology Advisor’s conference coverage.

Simoctocog alfa may be effective for treating and preventing bleeding episodes in previously untreated patients with severe hemophilia A, according to research presented at the 61st American Society of Hematology (ASH) Annual Meeting in Orlando, Florida.

Among patients with hemophilia A, especially those who were previously untreated, the development of FVIII inhibitors presents a serious clinical challenge. According to previously published data, recombinant FVIII (rFVIII) treatments developed using hamster cell lines appear to be effective for preventing and treating inhibitor development in previously untreated patients.

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For the open label, phase 3 NuProtect study, researchers evaluated whether simoctocog alfa, a fourth-generation rFVIII product created using a human cell line, is safe and effective among previously untreated patients with severe hemophilia A.

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Of 108 participants who consented to the study, 105 were previously untreated. Patients were treated for a median of 101 exposure days; 96 patients were treated for at least 100 days or until inhibitor development. Most patients with available genetic data (90/102; 88.2%) had null F8 mutations; 13 (12%) had a familial history of inhibitor development.

The all-inhibitor development rate was 27.9%, with 17.6% of patients developing high-titer inhibitors. No previously untreated patients with non-null F8 mutations had inhibitor development.

Among previously untreated patients who received simoctocog alfa for at least 6 months, the mean annualized bleeding rate was 0.54 for spontaneous bleeding events and 3.61 for all bleeding events. However, of the 804 noted bleeding events, treatment was successful in 92.9% of cases.

One patient had a noninhibitor adverse event during the trial, which was a mild rash.

“These results complement results in previously treated patients and support the use of simoctocog alfa in the prevention and treatment of bleeding episodes in [both] previously untreated patients and previously treated patients,” the researchers concluded.

Disclosures: Some authors have declared affiliations with the pharmaceutical industry. Please refer to the original study for a full list of disclosures.


1.     Liesner R, Neufeld EJ. Inhibitor development with simoctocog alfa in previously untreated patients with severe haemophilia A: final results of the NuProtect study. Oral presentation at: 61st ASH Annual Meeting and Exposition; December 7-10, 2019; Orlando, FL. Abstract 903.