• Male and female adult participants ≥ 18 years of age with diagnosis of aHUS for whom etiologies of other types of TMA and non-aHUS kidney disease have been excluded.

• Currently on the recommended weight-based dosage regimen of anti-C5 antibody treatment for at least 3 months prior to the screening visit.

• Clinical evidence of response to anti-C5 antibody treatment (in absence of PE/PI) for at least 3 months prior to entering the screening period as defined by:

‣ Hematological normalization in platelet count ≥150 x 109/L and LDH below upper limit of normal \[ULN\], and

⁃ Stable or improving kidney function as defined by ≤15% increase in serum creatinine.

• Vaccination against Neisseria meningitidis and Streptococcus pneumoniae infections is required prior to the start of treatment with iptacopan.

• If not received previously or if a booster is required, vaccination against Haemophilus influenzae infection, should be given, if available and according to local regulations.