FDA Approves Fitusiran as Prophylaxis of Bleeding Episodes Due to Hemophilia A or B

The FDA approved fitusiran (Qfitlia; Sanofi) for routine prophylaxis to prevent or reduce the frequency of bleeding episodes for patients 12 years and older with hemophilia A or B, with or without factor VIII or IX inhibitors. Fitusiran is a subcutaneous injection that is administered once every 2 months.¹

Fitusiran (Qfitlia) is approved for patients 12 years and older with or without factor VIII or IX inhibitors. | Image Credit: ImageFlow | stock.adobe.com

"Today's approval of Qfitlia is significant for patients with hemophilia because it can be administered less frequently than other existing options," Tanya Wroblewski, MD, deputy director of the division of non-malignant hematology in the FDA's Center for Drug Evaluation and Research, said in a news release.¹ "This new treatment option highlights our continued efforts to improve the lives of patients with hemophilia."

The approval was based on 2 multicenter, randomized clinical trials that included a total of 177 adults and pediatric male patients who had either hemophilia A or B. In the first study (NCT03417102), investigators aimed to determine the frequency of bleeding episodes for individuals who received fitusiran as prophylactic treatment compared with those who received their regular medication. The total time of the study, including screening, was up to 11 months, and patients had the opportunity to enroll in the extension study. Treatment duration with fitusiran was 9 months. For those who did not enroll in the extension, the total time was up to 17 months due to an additional 6 months of follow-up to monitor for antithrombin levels.²

Investigators included male patients 12 years or older with either hemophilia A or B with inhibitors and a minimum of 6 bleeding episodes requiring bypassing agent treatment in the last 6 months. The primary outcomes included estimated and annualized annualized bleeding rate (ABR) for treated bleeding from day 29 to day 246. The secondary outcomes included estimated and observed ABR from day 1 up to day 246, estimated and observed annualized spontaneous bleeding rates from day 29 up to day 246, estimated and observed annualized joint bleeding rates from day 29 up to day 246, health-related quality of life, and the number of individuals with treatment-emergent adverse events (AEs).²

In the second study (NCT03417245), investigators compared fitusiran with on-demand treatment with factor concentrates. Patients included were 12 years or older with severe hemophilia A or B without inhibitors and a minimum of 6 bleeding episodes requiring factor concentrate treatment within the last 6 months. The primary and secondary outcomes were the same for this trial.⁴

Investigators found that there was a 73% reduction in estimated ABR compared with patients who received on-demand treatment with a bypassing agent in study 1 and 71% for those receiving closing factor concentrates in study 2. The most common AEs included viral infection, nasopharyngitis, and bacterial infection.¹

Furthermore, the FDA included a boxed warning for thrombotic events and gallbladder disease as well as warnings of liver toxicity that should be monitored monthly for at least 6 months following initiating treatment or increasing the dose.¹

REFERENCES

1. FDA approves novel treatment for hemophilia A or B, with or without factor inhibitors. News release. FDA. March 28, 2025. Accessed March 28, 2025. https://prnmedia.prnewswire.com/news-releases/fda-approves-novel-treatment-for-hemophilia-a-or-b-with-or-without-factor-inhibitors-302414562.html

2. A study of fitusiran (ALN-AT3SC) in severe hemophilia A and B patients with inhibitors (ATLAS-INH). ClinicalTrials.gov identification: NCT03417102. Updated March 28, 2022. Accessed March 28, 2025. https://clinicaltrials.gov/study/NCT03417102

3. A study of fitusiran (ALN-AT3SC) in severe hemophilia A and B patients without inhibitors. ClinicalTrials.gov identification: NCT03417245. Updated March 28, 2022. Accessed March 28, 2025. https://clinicaltrials.gov/study/NCT03417245