Efficacy and Safety of AMG 570 in Subjects With Active Systemic Lupus Erythematosus (SLE)

Inclusion Criteria Screening Visit: - Subject has provided informed consent prior to initiation of any study-specific activities/procedures. - Age ≥ 18 years to ≤ 75 years at screening visit. - Fulfills classification criteria for SLE according to the 2019 European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) classification criteria for SLE (Aringer et al, 2019), with antinuclear antibody ≥ 1:80 by immunofluorescence on Hep-2 cells being present at screening. - Hybrid SLEDAI score ≥ 6 points with a "Clinical" hSLEDAI score ≥ 4 points. The "Clinical" hSLEDAI is the hSLEDAI assessment score without the inclusion of points attributable to laboratory results, including urine or immunologic parameters. - Additional protocol-specific rules are applied at screening and throughout the study, as follows: • Arthritis: Arthritis (at least 3 tender and swollen joints) must involve joints in the hands or wrists for the hSLEDAI scoring. • Alopecia: Subjects should have hair loss without scarring; should neither have alopecia areata nor androgenic alopecia; and should have a CLASI activity score for alopecia ≥ 2. • Oral ulcers: Ulcers location and appearance must be documented by the investigator. • Scleritis and Episcleritis: the presence of stable SLE-related scleritis and episcleritis must be documented by an ophthalmologist and other causes excluded. • Renal: subjects with urine protein/creatinine ratio < 3000 mg/g (or equivalent method) in a clear catch spot urine sample can enroll and be scored in the hSLEDAI, provided the subject has a clinical hSLEDAI ≥ 4 and did not receive induction treatment for nephritis within the last year. • Pleurisy and Pericarditis: symptoms of pleurisy and pericarditis must be accompanied by objective findings to be scored in the hSLEDAI. - Unless there is a documented intolerance, subjects must be taking: • Only 1 of the following SLE treatments: anti-malarial (hydroxychloroquine, chloroquine, or quinacrine), azathioprine, methotrexate, leflunomide, mycophenolate mofetil/acid mycophenolic, or dapsone. OR • 2 of the above-mentioned SLE treatments in which 1 must be anti-malarial (hydroxychloroquine, chloroquine, or quinacrine). - Treatment should be taken for ≥ 12 weeks prior to screening and must be a stable dose for ≥ 8 weeks prior to screening. - For subjects taking OCS, dose must be ≤ 20 mg/day of prednisone or OCS equivalent, and the dose must be stable at baseline visit for ≥ 2 weeks prior to screening visit. Exclusion Criteria Screening Visit Subjects are excluded from the study if any of the following criteria apply: Disease Related - Urine protein creatinine ratio ≥ 3000 mg/g (or equivalent) at screening or induction therapy for lupus nephritis within 1 year prior to screening visit. - Active CNS lupus within 1 year prior to screening including, but not limited to, aseptic meningitis, ataxia, CNS vasculitis, cranial neuropathy, demyelinating syndrome, optic neuritis, psychosis, seizures, or transverse myelitis.