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

The purpose of this study is to evaluate the efficacy and safety of MK-6194 in adult participants with systemic lupus erythematosus.

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 unstable angina pectoris within 6 months prior to Screening. * Has a severe chronic pulmonary disease requiring oxygen therapy. * Has a transplanted organ which requires continued immunosuppression. * Has a known systemic hypersensitivity to interleukin-2 (IL-2), or modified IL-2 including MK-6194, or its inactive ingredients. * Has a known history of lymphoproliferative disease, including lymphoma, or signs and symptoms suggestive of possible lymphoproliferative disease, such as lymphadenopathy and/or splenomegaly. * Has drug-induced cutaneous lupus erythematosus (CLE) and/or drug-induced SLE in the setting of continued treatment with a causative agent. * Has active or unstable neuropsychiatric lupus including but not limited to the following: seizure, new or worsening impaired level of consciousness, psychosis, delirium or confused state, aseptic meningitis, cranial neuropathy, cerebrovascular accident, ascending or transverse myelitis, chorea, cerebellar ataxia, mononeuritis multiplex, or demyelinating syndromes. * Has a diagnosis of antiphospholipid syndrome (APS) with history of vascular thrombosis, catastrophic APS, or pregnancy morbidity within 6 months prior to Screening. * Has a history of any malignancy, except for successfully treated non-melanoma skin cancer or localized carcinoma in situ of the cervix. * Has an active or clinically significant infection requiring hospitalization or treatment with anti-infectives. * Has evidence of active tuberculosis (TB), latent TB, or inadequately treated TB. * Has confirmed or suspected coronavirus disease of 2019 (COVID-19) infection. * Has had major surgery within 3 months prior to Screening or has a major surgery planned during the study. * Is taking more than 1 immunosuppressant. * Is taking more than 1 oral nonsteroidal anti-inflammatory drug (NSAID), excluding low-dose aspirin (\