This is a 3-part, parallel group treatment, Phase 1, randomized, double-blind, placebo-controlled study to assess the safety, tolerability and pharmacokinetics after sequential single and multiple ascending doses of SAR443765 in healthy adult participants, and after a single dose of SAR443765 in participants with mild-to-moderate asthma.

The anticipated study duration per participant is up to 14 weeks

Inclusion Criteria:

• Diagnosis of asthma for at least 12 months and confirmed at screening based on the Global Initiative for Asthma (GINA) 2020 Guidelines
• Controlled asthma defined as no more than 1 canister of rescue inhaler per month over the last 3 months prior to baseline
• Elevated FeNO level defined as ≥25 ppb
• Participants, using as-needed SABA, ICS-naïve or with existing stable treatment (at least for 3 months prior to screening) with low to medium daily dose ICS (≤500 mcg of fluticasone propionate or comparable ICS daily dosage) potentially in combination with a LABA and/or LAMA as second controller, and/or with stable daily leukotriene receptor antagonist, leukotriene synthesis inhibitor and/or chromones
• Prebronchodilator forced expiratory volume in 1 second (FEV1) ≥60% of predicted normal
• Reversibility of at least 12% and 200 mL in FEV1 or forced vital capacity (FVC) after administration of 4 puffs (400 mcg) of albuterol/salbutamol or levalbuterol/levosalbutamol during screening or documented history of a reversibility test that meets this criteria within 5 years prior to screening or documented positive response to methacholine challenge (a decrease in FEV1 by 20% [PC20] of <8 mg/mL) within 5 years prior to screening visit
• Body weight between 50.0 and 105.0 kg, inclusive, if male, and between 40.0 and 95.0 kg, inclusive, if female, body mass index between 18.0 and 32.0 kg/m2
• Male participants are eligible to participate if they use condom during study period
• 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 non-childbearing potential (WONCBP) OR Is a woman of childbearing potential (WOCBP) and agrees to use a contraceptive method that is highly effective
• A WOCBP must have a negative highly sensitive pregnancy test within 36 hours before the first administration of study intervention

Exclusion Criteria:

Participants are excluded from the study if any of the following criteria apply:

• Any clinically relevant abnormal findings in medical history, physical examination, vital signs, 12-lead ECG.
• Chronic lung disease, or another diagnosed pulmonary or systemic disease associated with elevated peripheral eosinophil counts.
• History of life-threatening asthma, asthma exacerbation or use of systemic steroid within 3 months prior to screening visit
• Worsening of asthma or respiratory infection within the last 6 weeks prior screening visit.
• Symptomatic postural hypotension,history or presence of drug or alcohol abuse, current smoker or previous smoker with a smoking history >10 pack-years.
• Excessive consumption of beverages containing xanthine bases (more than 4 cups or glasses per day).

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.

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