This is a multinational, randomized, placebo-controlled, parallel treatment, Phase 2, double-blind, 2 arm study evaluating the efficacy and safety of SAR441344 in comparison with placebo in the treatment of participants aged 18 to 70 years with active Systemic Lupus Erythematosus (SLE). Study details include:

• Study duration: 36 weeks
• Treatment duration: 24 weeks
• Visit frequency: every 2 weeks

Inclusion Criteria:

• Diagnosis of SLE for at least 6 months prior to screening by fulfilling the Revised Criteria for Classification of SLE according to the 1997 Update of the 1982 ACR criteria
• Positive antinuclear antibody (ANA) (titer ≥1:80) during screening
• Positivity for at least one serological characteristic
• Total hSELENA-SLEDAI score ≥6 (including points attributed from arthritis and rash) during screening and at least 4 points from clinical features at randomization as confirmed by a Sponsor-selected independent reviewer(s)
• At least 1 BILAG A score or 2 BILAG B scores during screening as confirmed by a Sponsor-selected independent reviewer(s)
• Receiving at least one of the standard of care (SOC) for SLE (combination is possible)
• Body weight within 45 kg to 120 kg (inclusive) at screening
• Contraceptive use by men or women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies.

Exclusion Criteria:

• Primary diagnosis of a rheumatic disease besides SLE or an inflammatory joint or skin disease other than SLE that could confound the disease activity assessments
• Active and severe lupus nephritis
• Active severe or unstable neuropsychiatric SLE including but not limited to seizures, psychosis, acute confusional state, transverse myelitis, central nervous system vasculitis and optic neuritis
• Known or suspected drug-induced lupus
• History, clinical evidence, suspicion or significant risk, for thromboembolic events, as well as myocardial infarction, stroke, and/or antiphospholipid syndrome and any participants requiring antithrombotic treatment
• History or current hypogammaglobulinemia
• Serious systemic viral, bacterial or fungal infection
• Participants with a history of invasive opportunistic infections, such as, but not limited to histoplasmosis, listeriosis, coccidioidomycosis, candidiasis, pneumocystis jirovecii, and aspergillosis, regardless of resolution
• Evidence of active or untreated latent tuberculosis as documented by medical history (eg, chest Xrays) and examination, and tuberculosis testing
• High dose of steroids, or a change in dose within 4 weeks prior to randomization
• High dose of antimalarial, or a change in dose within 12 weeks prior to randomization
• High dose of immunosuppressants or a change in dose within 12 weeks prior to randomization
• Use of cyclophosphamide within 3 months prior to screening
• Previous parenteral (IV), intramuscular (IM), or intra-articular steroid administration within 4 weeks prior to randomization
• Participants likely to require multiple courses of oral corticosteroid (OCS) during the study for chronic diseases other than SLE
• Administration of any live (attenuated) vaccine within 3 months prior to randomization (eg, varicella zoster vaccine, oral polio, rabies)
• Administration of any non-live vaccine (eg, seasonal influenza, COVID-19) within 4 weeks prior to randomization

The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org