Study of ALXN1920 in Adult Participants With Primary Membranous Nephropathy (PMN)

Inclusion Criteria

• •Participants who have a documented diagnosis of PMN, established by positive antiPLA2R antibody level (\> 20 RU/mL) at Screening, which must be confirmed by a central laboratory
• •Participants are willing to receive the background Standard of Care (SoC)
• •Participants at high risk for disease progression, defined as:
• •1. Receiving ACE inhibitor or ARB for a minimum of 8 weeks prior to Screening, with the dose titrated to the maximally tolerated level. Participants with less than 8 weeks on ACE inhibitor or ARB before Screening or who have not yet reached maximally tolerated dose will enter the Run-in Period.
• •2. Participants who are on ACE inhibitor or ARB for a minimum of 8 weeks with Systolic Blood Pressure \< 140 mmHg in ≥ 75% of the readings within last 8 weeks.
• •3. Having two proteinuria measurements with each \> 3.5 g/day, the second measurement showing ≤50% decrease from the first measurement.
• •eGFR60 mL/min/1.73 m2 during Screening calculated by CKD-EPI 2021 creatinine formula
• •All participants must receive prophylactic treatment with appropriate antibiotics while receiving Rituximab (RTX), and be willing to be vaccinated against Neisseria meningitidis