C3 and cold agglutinin disease: Complement pathway biomarker data, as measured by the Wieslab, factor Bb and sC5b‐9 levels, indicated that full target engagement of factor B by iptacopan was sustained throughout the Part A treatment period for most patients in both the ITP (Figure S2A–C) and CAD cohorts (Figure S3A–C), whereas no significant impact on complement components C3 (Figures S2D,S3D) and C4d was observed (Figures S2E,S3E).