The Bioverativ acquisition looks unlikely to be worth the $11.6bn that Sanofi spent on it, but a couple of interesting rare disease assets are emerging from the pipeline. Today Ash saw the first detailed data on sutimlimab in cold agglutinin disease (CAD), a complement-mediated and very rare form of autoimmune haemolytic anaemia, in which sufferer’s red blood cells are destroyed. CAD patients suffer periods of acute and dangerous anaemia called acute haemolytic crises; these require blood transfusions or plasmapheresis and severe patients become transfusion-dependent. The Cardinal data concern these patients – a pre-transfusion trial called Cadenza reads out next year – and for now the signs are promising. 54.2% of patients responded, meeting the primary endpoint, while 71% remained free of transfusions out to week 26 – encouraging considering that existing treatments wane in effectiveness in this condition. Sutimlimab was declared “practice changing” by investigators although commercially it will not move the needle much for Sanofi; consensus sits at $167m in 2024, according to EvaluatePharma. Still, other markets might open up yet for sutimlimab: data from a small trial in immune thrombocytopenia, a condition that is also driven by complementary activating autoantibodies, should emerge soon.