Robert F. Sidonio, Jr., MD, MSc

Sidonio discussed how fitusiran may improve the treatment landscape and reduce treatment burden for people with hemophilia A or B with or without inhibitors.

Anticipating Fitusiran’s Approval for Factor-Agnostic Hemophilia A, B, with Robert F. Sidonio Jr., MD, MSc

The FDA is nearing a decision on fitusiran prophylaxis in adults and adolescents over the age of 12 years with hemophilia A or B, with or without inhibitors, as we approach the therapy’s Prescription Drug User Fee Act (PDUFA) date of March 28. The agency previously accepted Sanofi’s biologics license application (BLA) in June 2024.

spoke with Robert F. Sidonio Jr., MD, MSc, who is a Pediatric Hematologist/Oncologist, Medical Director of Hemophilia, and Medical Director of the Clinical Research Office at Aflac Cancer & Blood Disorders Center and Children's Healthcare of Atlanta, as well as an Associate Professor of Pediatrics at Emory University School of Medicine, to learn more about fitusiran and its potential to add to the treatment landscape of both hemophilia A and B.

“Fitusiran being once every 2 months, likely in most patients, that's about as low administrative burden as you can get, short of gene therapy or a definitive cure. So, we're happy about having another option for patients. This could be a really good option for patients that have poor intravenous access, or if they may have not responded to other non-factor therapies… Certainly there'll be some products maybe better for others, but this one is an appealing one,” Sidonio told 

Sidonio stressed that compared to other therapies facing approval, fitusiran benefits from a very large pre-approval study series, the ATLAS series of trials, that has generated years of long-term safety and efficacy data. He anticipates the therapy’s approval, and past barriers of insurance and Medicaid coverage, expects uptake to be enthusiastic.

The ATLAS-PPX trial previously met its primary end point of reducing annualized bleeding rate (ABR), with fitusitan reducing ABR 79.7% (

 = .0021) from baseline compared to a reduction of 46.4% (

= .0598) with bypassing agent /clotting factor concentrate prophylaxis.

Sidonio's relevant disclosures include Biomarin.

1. Press Release: ISTH: Sanofi advances leadership in hemophilia with new data for ALTUVIIIO and fitusiran. News release. Sanofi. June 21, 2024. 

https://www.sanofi.com/en/media-room/press-releases/2024/2024-06-21-05-00-00-2902104

2. Kenet G, Nolan B, Zulfikar B, et al. Fitusiran prophylaxis in people with hemophilia A or B who switched from prior BPA/CFC prophylaxis: the ATLAS-PPX trial. 

. 2024;143(22):2256-2269. doi:10.1182/blood.2023021864

Robert F. Sidonio, Jr., MD, MSc

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