Sanofi has reported that results from Part A of the pivotal Phase III CARDINAL study showed its investigational, humanised monoclonal antibody, sutimlimab, hindered C1-activated hemolysis in patients with primary cold agglutinin disease (CAD).

Sutimlimab can potentially target and stop C1s in the classical complement pathway, which is part of the innate immune system.

A chronic autoimmune hemolytic anaemia, CAD causes the immune system of the body to wrongly attack healthy red blood cells and lead to their rupture (hemolysis).

Part A of the 26-week, open-label, single-arm study enrolled 24 CAD patients with recent blood transfusion history.

The trial met the primary and secondary endpoints and showed continued inhibition of classical complement pathway-mediated hemolysis by sutimlimab with improvements in anaemia a week after the treatment was administered.

Data showed that 54% of the subjects met the composite endpoint criteria while 62.5% achieved a haemoglobin ≥12 g/dL or a hike of at least 2g/dL and 71% were transfusion-free after week five.

The study results also demonstrated improvements in normalisation of bilirubin and fatigue and 22 of 24 patients (91.7%) experienced at least one treatment-related adverse event.

The trial principal investigator Alexander Röth said: “The New England Journal of Medicine ’s publication of these pivotal results underscore the clear and clinically meaningful treatment effect of sutimlimab on classical complement pathway activation, which triggers chronic hemolysis and anaemia experienced by people living with cold agglutinin disease.

“These results are promising because of patients’ sustained response to sutimlimab over the duration of the study.”

On concluding the Part A treatment period, eligible subjects were enrolled in an extension study to receive sutimlimab for an additional 24 months (Part B) to assess the long-term safety and durability of response.

Sutimlimab has received Breakthrough Therapy and Orphan Drug designations from the US Food and Drug Administration.