A Study to Evaluate the Safety, Tolerability and Pharmacokinetics of AZD5148 in Healthy Adults

Inclusion Criteria:

• Healthy participants with suitable veins for cannulation or repeated venipuncture atthe time of consent.

• All women must have a negative serum pregnancy test at the Screening Visit.

• Women of childbearing potential must have a negative urine pregnancy test onadmission to the Clinical Unit.

• Women of childbearing potential must not be lactating and if heterosexually activemust agree to use an approved method of highly effective contraception, to avoidpregnancy from 3 months prior to administration of the study drug and until 360 daysafter the dose of the study drug.

• Women of non-childbearing potential must be confirmed at the Screening Visit byfulfilling one of the following criteria:

1. Postmenopausal defined as amenorrhea for at least 12 months following cessationof all exogenous hormonal treatments and follicular stimulating hormone (FSH)levels in the postmenopausal range.

2. Documentation of irreversible surgical sterilization by complete hysterectomy,bilateral oophorectomy, or bilateral salpingectomy but not tubal ligation ortubal occlusion.

• Have a Body mass index ≥ 18.0 to ≤ 32.0 kg/m2 and weigh ≥ 45 kg and ≤ 110 kg.

• Willing and able to complete the Follow-up Period through Day 361.

• Healthy Chinese participants - participants of Chinese descent are eligible based onmeeting all of the following specific criteria for these two cohorts (Cohorts 2b and 4b):

1. Participant with Chinese ancestry, born in mainland China, Hong Kong, orTaiwan.

2. Participant is the descendant of 4 ethnic Chinese grandparents and 2 ethnicChinese parents.

3. Participant has lived outside China for ≤ 10 years at the time of Screening.

4. Exhibits no significant change in lifestyle, including diet, since leavingChina.

Exclusion Criteria:

• History of any clinically important disease or disorder which may either put theparticipant at risk because of participation in the study or influence the resultsor the participant's ability to participate in the study.

• Any clinically important illness, medical/surgical procedure, or trauma within 4weeks of the first administration of study drug.

• History of malignancy other than treated non-melanoma skin cancers or locallytreated cervical cancer in previous 5 years.

• Any medical history of symptomatic CDI within the prior 2 years.

• Any clinically important abnormalities in laboratory values, vital signs, clinicalchemistry, hematology, or urinalysis results.

• Any positive result on Screening for serum Hepatitis B surface antigen (HBsAg) orHepatitis C virus (HCV).

• Primary or acquired immunodeficiency, including HIV infection or due to drugs,including any course of glucocorticoid therapy exceeding 2 weeks of prednisone orequivalent within 6 months prior to Screening. Human immunodeficiency virus (HIV)testing must be negative at Screening Visit.

• Any clinically important abnormalities in rhythm, conduction, or morphology of theresting 12-lead electrocardiogram, at Screening.

• Known or suspected history of alcohol or drug abuse within the past 2 years thatmight affect assessments of safety or ability of participant to comply with allstudy requirements.

• Positive screen for drugs of abuse, or alcohol at Screening or Day -1.

• History of severe allergy/hypersensitivity or ongoing clinically importantallergy/hypersensitivity to drugs with a similar chemical structure or class to thestudy drug.

• History of previous hypersensitivity, infusion-related reaction, or severe adversereaction following administration of monoclonal antibodies (mAbs).

• Previous receipt of a mAb within 6 months, or 5 antibody half-lives (whichever islonger), prior to the start of the study.

• Plasma donation within one month of the Screening Visit or any blood donation/bloodloss > 500 mL during the 3 months prior to the Screening Visit.

• Receipt of immunoglobulin or blood products, or expected receipt, within 6 monthsprior to Screening or expected to receive during the study.

• Clinically significant bleeding disorder (e.g., factor VIII deficiency,coagulopathy, or platelet disorder), or prior history of significant bleeding orbruising following IM injections or venipuncture.

• Vulnerable participants, e.g., kept in detention, protected adults underguardianship, trusteeship, or committed to an institution by governmental orjuridical order.