Inclusion Part A and B

* Participants must be capable of giving informed consent and have provided informed consent.
* Participants must be 18 to 65 inclusive at time of signing of informed consent.
* Participants must have a Body Mass Index between 18.0 to 30 kg/m2 and total body weight ≥ 40 kg at screening.
* Participants must be overtly healthy as determined by the investigator based on medical evaluation and study screening procedures.
* Female participants must be of non-childbearing potential.

Inclusion Part C

* Participants must be capable of giving informed consent and have provided informed consent.
* Participants must be 18 to 65 inclusive at time of signing of informed consent.
* Participants must have documentation of physician diagnosed asthma for ≥ 12 months prior to screening.
* Participants must have documented bronchodilator responsiveness of forced expiratory volume in 1 second (FEV1) ≥ 12% and ≥200 mL in the 12 months before screening or at the screening visit.
* Participants must have a pre-bronchodilator percent predicted FEV1 between 55 and 85% inclusive at screening visit and Day -1.
* Participants must have peripheral blood eosinophils ≥ 300 /ul at screening visit and Day -1
* Participants must have a fractional exhaled nitric oxide (FeNO) ≥ 30 ppb at screening visit and Day -1.
* Participant must not use inhaled corticosteroids (ICS) or must be treated with low-dose or medium-dose ICS and on a stable dose for a minimum of 12 weeks prior to screening.

Exclusion (applicable to all study parts)

* History of malignancy (except for in situ cervical cancer or surgically excised non-melanoma skin cancer occurring more than 5 years prior to randomization).
* History of anaphylaxis or hypersensitivity to biologic therapy or sensitivity to mammalian derived products.
* History of immunodeficiency or history of severe infection within the last 3 years requiring IV antibiotics.
* History of tuberculosis (TB), TB symptoms, or positive interferon gamma release assay.
* History of untreated or unresolved helminthic infection within 24 weeks of day 1.
* Positive human immunodeficiency virus (HIV) antibodies, hepatitis B core antigen, hepatitis B core antibody, or hepatitis C virus (HCV) ribonucleic acid (RNA).
* Male participants unwilling to follow contraceptive requirements.

Additional Exclusion for Part C only

* Female of childbearing potential not willing to use 2 methods of contraception with one being a highly effective method of contraception.
* History of pulmonary disease that may interfere with interpretation of study results.
* History of upper respiratory infection within 6 weeks of screening.
* Asthma Control Questionnaire (ACQ-6) \> 3
* Asthma symptoms or exacerbations requiring 2 or more systemic corticosteroid bursts (≥10 mg/day prednisone or equivalent for ≥ 3 days each) in the previous 12 months.
* More than one hospitalization or emergency department visit in the last year.
* History of life-threatening asthma exacerbation requiring admission to intensive care unit.

Note: Other protocol defined Inclusion/Exclusion Criteria may apply.

Eligibility last updated 6/12/2025. Questions regarding updates should be directed to the study team contact.