The purpose of this study is to assess the PK, PD, and safety of anifrolumab as SC administration or IV infusion in adult participants with systemic lupus erythematosus (SLE).

This is a multicentre, randomised, phase I open-label study.

The study will comprise of the following:

• Screening period: Up to 30 days
• Two treatment periods
• Part A: Randomised SC vs IV Treatment Period: 5 weeks
• Part B: Optional Extended Treatment Period: Up to 47 weeks
• Safety follow-up period: 12 weeks after the final dose

Part A will include all participants who will be randomised into SC anifrolumab via autoinjector (AI) or IV anifrolumab.

Part B is an optional extended treatment period where participants will receive SC anifrolumab via accessorised prefilled syringe (aPFS).

Inclusion Criteria:

• Participants who have a diagnosis of adult SLE according to the European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) 2019 criteria for ≥ 24 weeks prior to signing the informed consent form (ICF).
• "Clinical" Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) ≥ 4 points at Screening.
• Antinuclear antibody (ANA)-positive at Screening.
• Must be on stable background standard therapy with oral corticosteroids (OCS), antimalarials, and/or immunosuppressants alone or in combination.

Exclusion Criteria:

• Active severe or unstable neuropsychiatric SLE.

• Active severe SLE-driven renal disease.

• Known history of primary immunodeficiency, splenectomy, or any underlying condition predisposing to infection, or a positive result for Human Immunodeficiency Virus (HIV) infection confirmed by central laboratory at Screening.

• At Screening, confirmed positive test for hepatitis B serology or positive test for hepatitis C antibody.

• Any severe case of herpes zoster infection at any time prior to Week 0 (Day 1).

• Opportunistic infection requiring hospitalisation or IV antimicrobial treatment within 3 years of randomisation

• History of cancer, apart from:

  1. Squamous or basal cell carcinoma of the skin treated with documented curative success ≥ 3 months prior to Day 1.
  2. Cervical cancer in situ treated with apparent curative success ≥ 1 year prior to Day 1.

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.