Sanofi announced the results of its ATLAS-PPX study, which were presented at the International Society on Thrombosis and Haemostasis (ISTH) congress. They report that the fitusiran prophylaxis was significantly associated with a reduction in the estimated annualised bleeding rate (ABR) in adults and adolescents with severe haemophilia A or B.
Fitusiran is a small RNA interference-based therapy conjugated with GalNAc. The ATLAS-PPX study evaluated its efficacy for treating patients with haemophilia A or B. The clinical trial enrolled 80 patients (aged 12 years or more) with severe haemophilia A or B. The participants continued their usual prophylaxis regimen with a factor or bypassing agents for a six-month period followed by fitusiran treatment once monthly for seven months. The primary endpoint of the study was the overall median ABR.
No ABR was seen with fitusiran prophylaxis as compared to 4.4 ABR with prior prophylaxis. Further, 63.1% of adults treated with fitusiran did not experience any bleeding events as compared to only 16.9% of patients treated with prior factors. Also, median ABR for patients was zero with fitusiran in patients treated with or without inhibitors as compared to 6.6 and 4.4 for those on prior prophylaxis. The most common adverse events associated with fitusiran were increased alanine aminotransferase, nasopharyngitis and upper respiratory tract infection. Also, thromboembolic events were seen in two patients.
Fitusiran, an Investigational siRNA Therapeutic Targeting Antithrombin for the Treatment of Hemophilia: First Results from a Phase 3 Study to Evaluate Efficacy and Safety in People with Hemophilia a or B without Inhibitors (ATLAS-A/B)