A Study to Investigate Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of AZD5492 in Adult Participants With Systemic Lupus Erythematosus or Idiopathic Inflammatory Myopathies or Rheumatoid Arthritis.

Inclusion Criteria15

• Participant must be 18 to 70 years of age inclusive, at the time of signing the informed consent.
• Diagnosis of SLE:
• Diagnosis of SLE according to the 2019 EULAR/ACR classification criteria for SLE
• Positive for one or more of: anti-nuclear antibodies (titre ≥ 1:80), anti-dsDNA or anti-Sm at screening.
• Active, moderate-severe disease at screening, defined as clinical SLEDAI-2K ≥ 4.
• Intolerance to, or inadequate response following at least 3 months of use to, ≥ 3 available treatments, such as the following: corticosteroids, anti-malarial drugs, calcineurin inhibitor, methotrexate, azathioprine, leflunomide, mycophenolic acid or its derivatives, cyclophosphamide, belimumab, anifrolumab, telitacicept, or B-cell depleting monoclonal antibodies.
• Diagnosis of IIM:
• Must have "probable" or "definite" diagnosis of PM or DM (excluding IBM and cancer associated myositis) according to the 2017 EULAR/ACR classification criteria for adult myositis.
• Positive for ≥ 1 disease-specific autoantibody at screening.
• MMT-8 score of ≤ 142/150 and/or CDASI-A ≥ 6
• Fulfill at least one of the following criteria of active disease at screening:
• (i) One or more muscle enzyme elevation (CK, AST, ALT, aldolase, LDH) ≥ 1.3 × ULN (ii) If criterion 3(d)(i) is not met, then at least one of the following criteria must be met: a. Report from MRI performed within 3 months prior to screening with evidence of muscle inflammation b. Report from muscle biopsy performed within 3 months prior to screening that demonstrates active inflammation c. Report from electromyography performed within 3 months prior to screening that exhibits irritable myopathic pattern.
• (e) Intolerance or inadequate response to corticosteroids and ≥2 other SoC treatments, used for at least 3 months each, for which at least one must be a biologic SoC, immunoglobulin or cyclophosphamide.
• Diagnosis of RA:
• (a) Diagnosis of RA as defined by the 2010 EULAR/ACR classification criteria (b) Positive for ≥ 1 disease-specific autoantibody performed by the central laboratory at screening: RF or ACPA (c) Moderate or severe disease activity defined as: (i) ≥6 tender joints and ≥6 swollen joints AND (ii) DAS28-CRP \>3.2. (d) Intolerance to or inadequate response following approximately 3 month's treatment or longer to ≥2 b/tsDMARDs (with different mechanisms of action) after failing csDMARD therapy (unless csDMARD therapy is contraindicated). There is no minimum duration for taking a treatment in cases of intolerance.