Sanofi's treatment for rare anemia hits goal in 2nd phase 3

Paul Hudson
Sanofi CEO Paul Hudson (Sanofi)

A second phase 3 clinical trial of Sanofi’s sutimlimab in people with cold agglutinin disease has met its primary endpoint. The success of the second clinical trial positions Sanofi to seek approval for the C1s inhibitor in the EU.

Sanofi shared data from the first phase 3 trial late in 2019 before going on to seek FDA approval on the strength of the single pivotal study the next year. The FDA hit Sanofi with a complete response letter in November over deficiencies found in a pre-license inspection of a third-party manufacturing facility but cited no clinical nor safety deficiencies in the rejection.

A resubmission to the FDA is planned for the second half of the year. With the second phase 3 trial providing further evidence of the efficacy of sutimlimab, Sanofi is now also set up to file for approval in Europe in patients with the chronic autoimmune hemolytic anemia cold agglutinin disease.

The second phase 3 study randomized 42 patients to receive a fixed weight-based dose of sutimlimab or placebo via intravenous infusion. Sixteen of the 22 patients on sutimlimab had a 1.5-g/dL or more improvement in hemoglobin and were free from transfusions and the need for other non-permitted therapies after Week 5. The three measures made up the composite primary endpoint.

Hemoglobin improvements were statistically significant over placebo. The study that reported results in 2019 had a single arm, making the data shared by Sanofi at the European Hematology Association 2021 Congress the first time sutimlimab has shown efficacy over placebo in a randomized trial. 

Other data points discussed by Sanofi include fatigue as measured by FACIT-Fatigue assessment and change in bilirubin, a key marker of hemolysis. The C1s inhibitor comfortably beat placebo by those measures.

One patient had a treatment-emergent serious adverse event (TESAE) deemed by the investigator to be related to sutimlimab, namely a case of cerebral venous thrombosis in a person with a history of diabetes. The TESAEs headache, hypertension, rhinitis, Raynaud’s phenomenon and acrocyanosis were more common in the sutimlimab group than in the placebo cohort. 

Buoyed by the data, Sanofi, which picked up sutimlimab in its $11.6 billion takeover of Bioverativ, is pitching the drug as a potentially important therapy for the small number of people with the disease. 

“Cold agglutinin disease causes the body’s immune system to mistakenly destroy its healthy red blood cells. People living with cold agglutinin disease experience the crippling impact of chronic hemolysis that can cause severe anemia, profound fatigue and can have acute hemolytic crisis,” principal investigator Alexander Röth, M.D., of the University of Duisburg-Essen said in a statement.