The purpose of this study is to assess the safety, tolerability, pharmacokinetic, and efficacy of surovatamig administered by subcutaneous injection in adult participants with primary membranous nephropathy.

This is a Phase II open-label study to assess the safety, tolerability, Pharmacokinetics, and efficacy of surovatamig in adult participants with pMN, who are positive for anti-PLA2R antibodies and have heavy and persistent proteinuria with a high risk of progressing to end stage kidney disease.

The study will be conducted across approximately 30 to 40 study sites in approximately 10 countries. The study consists of 2 parts (Part A Multiple ascending with sentinel dosing and Part B Multiple ascending doses), with each consisting of 3 periods (ie, screening period, treatment period, and follow-up period; up to 26 months in total).

Inclusion Criteria:

1. Participant must be 18 (or the legal age of consent in the jurisdiction in which the study is taking place) to 75 years of age inclusive, at the time of signing the informed consent.
2. Diagnosis of anti-PLA2R antibody-positive pMN.
3. All participants must have received SoC therapy with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers for ≥ 4 weeks, with exceptions in case of intolerance, contraindications, or low blood pressure, before the screening period.
4. Positive for anti-PLA2R.
5. Up to date with required vaccinations as per institutional guidelines (eg, influenza, pneumococcal, and severe acute respiratory syndrome coronavirus 2) prior to study entry.
6. Male and/or female assigned at birth, inclusive of all gender identities. Contraceptive use by participants or participant partners should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies.
7. Capable of giving signed informed consent

Exclusion Criteria:

1. Receipt of B cell-depleting therapy including CD19- or CD20-directed monoclonal antibodies < 9 months before screening.
2. Immunomodulatory therapy <3 months before screening.
3. Secondary causes of membranous nephropathy
4. Diabetes mellitus with haemoglobin A1C > 8.5% tested at screening visit.
5. Malignancies
6. History of HLH/MAS. 7 Significant CNS co-morbidity

8. History of chronic significant respiratory disease. 9. Significant opportunistic infection in the medical history deemed relevant by the Investigator.

10. Abnormal vital sign after 10 minutes sitting at rest. 11. Administration of corticosteroids such as prednisolone at doses exceeding 20 mg or an equivalent agent < 2 months before screening.

Qualified researchers can request access to anonymized individual patient-level data from AstraZeneca group of companies sponsored clinical trials via the request portal Vivli.org. All requests will be evaluated as per the AZ disclosure commitment: https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.

Yes, indicates that AZ are accepting requests for IPD, but this does not mean all requests will be shared.

AstraZeneca will meet or exceed data availability as per the commitments made to the EFPIA PhRMA Data Sharing Principles. For details of our timelines, please rerefer to our disclosure commitment at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.

When a request has been approved AstraZeneca will provide access to the anonymized individual patient-level data via secure research environment Vivli.org. Signed Data Usage Agreement (non-negotiable contract for data accessors) must be in place before accessing requested information.