A Phase 1, first-in-human, three-part, randomized, double-blind, placebo-controlled study to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of SAR443726 in healthy adult participants and in adult participants with moderate-to-severe atopic dermatitis.

PDY16891:
- Confirmed diagnosis of moderate-to-severe AD for at least 1 year prior to
first administration of IMP on Day 1
- Quantiferon® - tuberculosis (TB) Gold test must be negative with no prior
history of documented tuberculosis irrespective of treatment.
- Eczema Area and Severity Index (EASI) score * 12 at screening and * 16 at
Baseline
- Validated IGA score of at least 3 or 4 at Baseline
- Atopic dermatitis involvement of *10% of BSA at Baseline
- Normal or clinically acceptable vital signs, standard 12-lead ECG parameters,
laboratory parameters within the normal range
- Body weight between 50.0 and 105.0 kg, inclusive, if male, and between 45.0
and 95.0 kg, inclusive, if female, body mass index between 18.0 and 32.0 kg/m2,
inclusive
- Documented history, within 6 months prior to Baseline, of either inadequate
response to topical treatments or inadvisability of topical treatments
- Participants should make every effort to apply a stable dose of topical bland
emollient (simple moisturizer, no additives [eg, urea]) on lesional area at
least twice daily for at least 7 consecutive days before Baseline.
- Male participants must accept to use, during sexual intercourse, a double
contraception method.
- A female participant is eligible to participate if she is not pregnant or
breastfeeding, and one of the following conditions applies: is a woman of
nonchildbearing potential (WONCBP) ORIs a woman of childbearing potential
(WOCBP) and agrees to use a contraceptive method that is highly effective

PDY16891:
- Presence of dermatologic diseases other than AD that are susceptible to
interfere with clinical assessment of AD.
- Co-morbid clinically significant disease that might interfere with the
evaluation of IMP (eg. but not limited to: uncontrolled diabetes, severe
hypertension, severe ischemic heart disease, unstable angina in the last 6
months, unstable cardiac arrhythmias, and Class IV heart failure, renal,
hepatic or pulmonary disease, neurological condition, cancer any type).
Controlled hypertension under stable (unchanged in the last 6 months) treatment
with 1 antihypertensive is allowed.
- Evidence of acute or chronic infection requiring treatment with
antibacterials, antivirals, antifungals, antiparasitics, or antiprotozoals
within 4 weeks before Screening visit, significant viral infections within 4
weeks before Screening visit that may not have received antiviral treatment
(eg, influenza receiving only symptomatic treatment).
- Participants with autoimmune disease or using systemic immunosuppressive
therapy for autoimmune disease (eg, rheumatoid arthritis, inflammatory bowel
disease, primary biliary cirrhosis, systemic lupus erythematosus, multiple
sclerosis, etc).
- Significant blood loss (including blood donation [>450 mL] or plasma donation
[>200 mL], within 2 months prior to Screening.
- Symptomatic postural hypotension, irrespective of the decrease in blood
pressure, or asymptomatic postural hypotension defined as a decrease in
systolic blood pressure *30 mmHg within 3 minutes when changing from supine to
standing position.
- Presence or history of drug hypersensitivity, or relevant allergic disease
diagnosed and treated by a physician. Participants with a history of mild
seasonal allergies may be included at investigator discretion.
- History or presence of drug or alcohol abuse (alcohol consumption more than
40 g per day on a regular basis).
- Known or suspected history of immunosuppression, including history of
invasive opportunistic infections (eg, tuberculosis, histoplasmosis,
listeriosis, coccidioidomycosis, pneumocystosis, aspergillosis), despite
infection resolution; or unusually frequent, recurrent or prolonged infections,
per Investigator's judgment.
- Diagnosed active parasitic infection (helminths), suspected or high risk of
parasitic infection, unless clinical and (if necessary) laboratory assessments
have ruled out active infection before randomization.
- Any prior history of malignancy or active malignancy, including
lymphoproliferative diseases (except successfully treated carcinoma in-situ of
the cervix, non-metastatic squamous cell or basal cell carcinoma of the skin)
within 5 years prior to Screening visit.
- Treatment with TCS/TCI within 2 weeks prior to Baseline or systemic
corticosteroids within 4 weeks prior to Baseline for the management of AD.
- Treatment with phototherapy within 2 weeks prior to Baseline for the
management of AD.
- Exposure to investigational therapies (excluding biologics) within 3 months
prior to Baseline.
- Any recall vaccination with non-live vaccines including recall vaccination
for COVID-19 within the last 4 weeks before first IMP administration (Day 1).
- Administration of a live attenuated virus vaccine within 3 months before
Baseline/first IMP administration (Day 1).
- Initiation of prescription moisturizers (with or without additives such as
ceramide, hyaluronic acid, urea, or filaggrin), topical anesthetics or
antihistamines during the Screening period.
- Use of mycophenolate mofetil, azathioprine, methotrexate, cyclosporine,
dapsone, intravenous immunoglobulin (IVIG), Kineret (anakinra), Enbrel
(etanercept), or any other immunosuppressant not mentioned in this exclusion
criterion within 4 weeks or 5 half lives (whichever is longer) prior to
baseline.
- Use of infliximab, adalimumab, golimumab, abatacept, tocilizumab,
certolizumab pegol, secukinumab, interferon-gamma (IFN-*), JAK inhibitors,
dupilumab, and any other biologic or targeted synthetic disease modifier drug
not mentioned in this exclusion criterion or in exclusion criterion E 32, as
well as plasmapheresis within 12 weeks or 5 half-lives (whichever is longer)
prior to baseline.
- Use of anti-CD20 drugs such as rituximab, ofatumumab, other long-acting
biologics within 6 months prior to baseline (or shorter if there is documented
B cell reconstitution for anti CD20 drugs).
NOTE: Other Inclusion/Exclusion criteria may apply.
The above information is not intended to contain all considerations relevant to
a patient's potential participation in a clinical trial.