The purpose of this study is to investigate the safety, tolerability, and pharmacokinetics (PK) of AZD4604 when administered as single or multiple inhaled doses to healthy Japanese and Chinese participants.

This study will comprise of two parts: Part 1 and Part 2

Part 1 will investigate the safety, tolerability, and PK of inhaled AZD4604 following single ascending and multiple doses in healthy Japanese participants.

Part 1a will include three single ascending dose (SAD) cohorts and Part 1b will include one multiple dose cohort.

Part 2 will investigate the safety, tolerability, and PK of inhaled AZD4604 following single ascending and multiple doses in healthy Chinese participants.

Part 2a will include two SAD cohort and Part 2b will include one multiple dose cohort.

Part 1a and Part 2a will comprise of:

1. A Screening Visit within 28 days before dosing.
2. A treatment period (Day 1 to Day 7)
3. A final assessment on Day 7

Part 1b and Part 2b will comprise of:

1. A Screening Visit within 28 days before dosing.
2. A treatment period (Day 1 to Day 13)
3. A final assessment on Day 13

Inclusion Criteria:

• Japanese participants who are born in Japan, has 2 Japanese biological parents, 4 Japanese grandparents as confirmed by the interview and has lived outside Japan for less than 10 years at the time of screening.
• Chinese participants who are born in China, has 2 Chinese biological parents, 4 Chinese grandparents as confirmed by the interview and has lived outside China for less than 10 years at the time of screening.
• Have body mass index (BMI) between 18 and 30 kg/m2 and weigh at least 45 kg.
• Healthy participants must have a Forced Expiratory Volume at first breath (FEV1) ≥ 80% of the predicted value in accordance with American Thoracic Society (ATS)/European Respiratory Society (ERS) criteria at the Screening and admission visits.
• Female participants must have a negative pregnancy test.

Exclusion Criteria:

• History or presence of clinically important disease which may put participant at risk because of participation in study.
• Participant has an increased risk of infection.
• History of malignancy other than superficial basal cell carcinoma, having a first degree relative with lung cancer or disease history suggesting abnormal immune function.
• Has received any vaccine 30 days prior to first dose.
• Has a body temperature of > 37.7°C on Day -1.
• History or presence of gastrointestinal, hepatic, or renal disease or any other condition known to interfere with absorption, distribution, metabolism, or excretion of drugs.
• Any clinically important illness, medical/surgical procedure, or trauma within 4 weeks of the first administration of study intervention.
• Known or suspected history of drug abuse, alcohol abuse or excessive intake of alcohol.
• Current smokers or those who have smoked or used nicotine products (including e-cigarettes, vaping, and nicotine replacement therapy) within the previous 6 months or has a smoking history of > 5 pack-years.
• History of a serious or severe adverse reaction to AZD4604 or any of its additive constituents.
• History of severe allergy/hypersensitivity or ongoing clinically important allergy/hypersensitivity or history of hypersensitivity to drugs with a similar chemical structure or class to AZD4604.
• Plasma donation within 1 month of the Screening Visit or any blood donation/blood loss> 500 mL during the 3 months prior to the Screening Visit.
• Any clinically important abnormalities in rhythm, conduction or morphology of the resting electrocardiogram (ECG) and any clinically important abnormalities in the 12-lead safety ECG.
• Female participants who are planning a pregnancy during the study period or within 1 month after the last dose of study intervention.
• Abnormal vital signs at the Screening Visit, after 5 minutes supine rest.
• History of any significant respiratory disorders such as asthma (a history of childhood asthma without symptoms or treatment after the age of 10 years is allowable), chronic obstructive pulmonary disease, or idiopathic pulmonary fibrosis.

Qualified researchers can request access to anonymized individual patient-level data from AstraZeneca group of companies sponsored clinical trials via the request portal Vivli.org. All requests will be evaluated as per the AZ disclosure commitment: https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.

"Yes", indicates that AZ are accepting requests for IPD, but this does not mean all requests will be approved.

AstraZeneca will meet or exceed data availability as per the commitments made to the EFPIA/PhRMA Data-Sharing Principles. For details of our timelines, please refer to our disclosure commitment at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.

When a request has been approved AstraZeneca will provide access to the anonymized individual patient-level data via secure research environment Vivli.org. A Signed Data Usage Agreement (non-negotiable contract for data accessors) must be in place before accessing requested information.