Sanofi plans 2021 restart for pediatric hemophilia trial hit by fallout from thrombotic events

Paul Hudson
Sanofi CEO Paul Hudson (Sanofi)

Sanofi is planning to restart dosing and recruitment in its pediatric fitusiran clinical trial later this year. The study has been on hold since the identification of vascular thrombotic events in the wider hemophilia program late last year.

After pausing dosing in all fitusiran studies in late October, Sanofi restarted administration of the RNAi drug to adolescents and adults in the U.S. in December. As Sanofi explained at the Annual Congress of the European Association for Haemophilia and Allied Disorders in February, the restart was enabled by a change in the dosing regimen and the targeting of higher antithrombin levels.

At that time, Sanofi said the risk mitigation plan for the pediatric study was still in development. The French Big Pharma provided additional details in its first-quarter results Wednesday, outlining plans to restart dosing and recruitment of pediatric hemophilia A and B patients later this year.  

Sanofi disclosed its pediatric plans as part of a broader update about its pipeline, including details of its decision not to opt in on Regeneron’s REGN4018, REGN5459 or REGN5458. 

REGN4018 is a Mucin 16 bispecific antibody in phase 1/2 clinical development as a treatment for ovarian cancer. REGN5459 and REGN5458 are both anti-BCMA bispecifics Regeneron is studying in first-in-human multiple myeloma trials.  

Recent changes leave Sanofi free to develop rival drugs. “Sanofi no longer has any non-compete obligations on refused candidates under the amended and restated IO Discovery and Development agreement, which terminated on March 16 2021,” the French Big Pharma wrote in its update. 

Separately, Sanofi terminated development of ROR gamma T antagonist SAR441169 in psoriasis. Sanofi developed the drug through its collaboration with Lead Pharma and took it into phase 1 in 2019. Finally, Sanofi discontinued development of T-cell engaging multispecific antibody SAR440234 in leukemia. Sanofi took the anti-CD123 candidate into the clinic in 2018.