A Study of Subcutaneous Gefurulimab Using Prefilled Syringe Versus Autoinjector in Healthy Adult Participants

Inclusion Criteria:

1. Participants must be 18 to 65 years of age inclusive, at the time of signing theinformed consent.

2. Body weight within ≥ 50 to < 110 kg and body mass index (BMI) within the range 18.5to 30 kg/m2 (inclusive)

3. Participants who are healthy as determined by medical evaluation with no clinicallysignificant or relevant abnormalities as determined by medical history, physicalexamination, vital signs, 12-lead ECG, and clinical laboratory evaluation.

4. QT interval corrected using Fridericia's formula (QTcF) ≤ 450 msec for maleparticipants and ≤ 460 msec for female participants at Screening and prior to dosingon Day 1.

5. Documented vaccination against meningococcal infection from serogroups A, C, W, andY and serogroup B.

6. Male and female participants should adhere to study-specific contraceptive methods.

Exclusion Criteria:

1. History of any Neisseria meningitidis infection.

2. History or presence of cardiovascular, respiratory, hepatic, renal,gastrointestinal, endocrinological, hematological, or neurological disorders.

3. Abnormal blood pressure as determined by the Investigator.

4. History of latent or active TB (Tuberculosis) or exposure to endemic areas.

5. Allergy to monoclonal antibodies.

6. Clinically significant multiple or severe drug allergies, intolerance to topicalcorticosteroids, or severe posttreatment hypersensitivity reactions.

7. Lymphoma, leukemia, or any malignancy within the past 5 years except for basal cellor squamous epithelial carcinomas of the skin that have been resected with noevidence of metastatic disease for 3 years.

8. Current or chronic history of liver disease.

9. Known hepatic or biliary abnormalities.

10. Active systemic bacterial, viral, or fungal infection within 14 days prior todosing.

11. History of allergy or intolerance to penicillin or cephalosporin.

12. History of clinically significant allergic reaction (eg, anaphylaxis or angioedema)to any product.

13. Live vaccine(s) within 1 month prior to Screening or plans to receive such vaccinesduring the study.

14. Evidence of human immunodeficiency virus (HIV) infection (positive HIV type 1 ortype 2 antibody).

15. Evidence of hepatitis B infection (positive hepatitis B surface antigen [HBsAg] orpositive total hepatitis B core antibody [HBcAb] with negative surface antibody [anti-HBs]), or hepatitis C viral infection (positive HCV RNA).

16. Female participants who have a positive pregnancy test at Screening or Admission.

17. Positive prestudy drug/alcohol screen; positive result may be repeated once.