MSC2364447C Phase 1b in Systemic Lupus Erythematosus

Inclusion Criteria:

- Male or female of 18 to 65 years of age

- Diagnosis of systemic lupus erythematosus (SLE) (at least 4 of the 11 American College
of Rheumatology [ACR] classification criteria for SLE) of at least 6 months duration
at the Screening visit

- Positive test results for anti-nuclear antibody (ANA) (human epithelial cell-2 ANA
greater than or equal to [>=] 1:80) and/or anti-dsDNA antibody (>= 30 international
units per milliliter [IU/mL]) at the Screening visit

- At least 1 SLE disease manifestation (assessed by Systemic Lupus Erythematosus Disease
Activity Index-2000 [SLEDAI-2K]) other than positive antidsDNA and no central nervous
system (CNS) SLE (psychosis, organic brain syndrome, cranial nerve disorder, lupus
headache, or new-onset cerebrovascular accident)

- History of vaccinations as follows or vaccination against these pathogens during
Screening:

1. Vaccination against Streptococcus pneumoniae with pneumococcal polysaccharide
vaccine 23 or pneumococcal 13-valent conjugate vaccine as per local guidelines,
and

2. Vaccination against influenza virus (as per local seasonal recommendations).
Subjects receiving 1 or more of these vaccinations during screening must have at
least 2 weeks between the vaccination(s) and the date of randomization at Day 1.

- Other protocol defined inclusion criteria could apply

Exclusion Criteria:

- Active clinically significant CNS SLE

- Initiation or change in dose of anti-malarial treatment after the screening visit

- Within 2 weeks prior to Screening or during Screening: use of oral corticosteroids
greater than (>) 40 mg daily prednisone equivalent, use of any injectable
corticosteroids, or change in dose of corticosteroids

- Within 2 weeks prior to Screening, initiation or change in dose of
angiotensin-converting enzyme inhibitor or angiotensin receptor blocker, or
nonsteroidal anti-inflammatory drugs (NSAIDs).

- Within 2 months prior to Screening or during Screening: initiation of or change in
dose of methotrexate, mycophenolate (mofetil or sodium), or azathioprine

- Within 2 months prior to Screening or during Screening, use of cyclosporine,
tacrolimus, leflunomide, abatacept, anti-tumor necrosis factor alpha agents,
intravenous immunoglobulin, plasmapheresis, or other disease-modifying,
immunosuppressive, or immunomodulatory therapies not otherwise specified in protocol

- Within 6 months prior to Screening or during Screening: use of cyclophosphamide or
chlorambucil

- Within 12 months prior to screening or during screening: use of rituximab, belimumab,
or any other B cell-depleting or modulating therapies

- Within 1 month prior to Screening or during Screening, vaccination with live or
live-attenuated virus vaccine.

- Active clinically significant viral, bacterial or fungal infection, or any serious
episode of infection requiring hospitalization within the last 6 months - Estimated
glomerular filtration rate by the Modification of Diet in Renal Disease equation of
less than (<) 60 milliliter per minute per 1.73 square meter (mL/min/1.73 m^2), or
recent decline in kidney function, or proteinuria >= 3 gram per day (g/day) (spot
urine protein/creatinine ratio >= 3 mg/mg)

- Other protocol defined exclusion criteria could apply