Efficacy and Safety of MK-6194 in Adult Participants With Systemic Lupus Erythematosus (MK-6194-006)

Inclusion Criteria: The main inclusion criteria include but are not limited to the following: * Has a diagnosis of systemic lupus erythematosus (SLE) ≥6 months prior to Screening. * Is taking at least 1 background therapy (1 immunosuppressant or dapsone and/or 1 antimalarial and/or oral corticosteroids) for SLE. * Has positive antinuclear antibody (+ANA; titer ≥1:80) or positive anti-double-strand deoxyribonucleic acid (dsDNA) antibody or positive anti-Smith (anti-Sm) antibody, or positive anti-Sjögren's Syndrome A (SSA)/Ro antibody. * Has the presence of at least 1 of the following manifestations of SLE: active lupus rash with Cutaneous Lupus Erythematosus Disease Area and Severity Index-Activity (CLASI-A) erythema and scale/hypertrophy combined score \>2, or \>2 tender and swollen joints in wrists, metacarpophalangeals (MCPs), or proximal interphalangeals (PIPs). * Has a hybrid Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) total score of ≥6 and clinical hybrid SLEDAI score of ≥4. Exclusion Criteria: The main exclusion criteria include but are not limited to the following: * Has a concurrent clinically significant disease or clinically relevant laboratory abnormalities, or a history of any illness or medical condition that might confound the results of the study or poses an additional risk to the participant by their participation in the study. * Has symptomatic heart failure (New York Heart Association Class III or IV) or myocardial infarction or unstabl…