A Study to Evaluate Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of BIIB133 (Dapirolizumab Pegol) in Healthy Japanese and Caucasian Participants

The primary objective of the study is to assess the safety and tolerability of a single intravenous (IV) dose of dapirolizumab pegol (DZP) in Japanese healthy study participants compared with those of Caucasian healthy study participants.

The secondary objectives of the study are to assess the pharmacokinetic(s) (PK) of a single IV dose of DZP in Japanese and Caucasian healthy study participants, to evaluate ethnic sensitivity on the PK of DZP between body weight- and gender-matched Japanese and Caucasian healthy study participants and to evaluate the immunogenicity of a single IV dose of DZP in Japanese and Caucasian healthy study participants.


Eligibility Criteria:
Key Inclusion Criteria:

* Negative polymerase chain reaction (PCR) test result for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within 14 days of Day -1 (inclusive).
* Japanese study participant has both biological parents and all 4 grandparents of Japanese descent and, if living outside of Japan for more than 5 years, must maintain a Japanese diet.
* Caucasian study participant has both biological parents and all 4 grandparents of Caucasian descent.
* Have a body weight between 50 and 90 kilograms (kg) (inclusive) and body mass index (BMI) between 18.0 and 26.0 kilograms per meter square (kg/m\^2) (inclusive) at the Screening Visit.

Key Exclusion Criteria:

* History of any clinically significant cardiac, endocrine, gastrointestinal, hematologic, hepatic, immunologic, metabolic, urologic, pulmonary, neurologic, dermatologic, psychiatric, or renal disease, or other major disease, as determined by the Investigator.
* Have undergone major surgery in the last 6 months or plans to undergo elective major surgery during the study period.
* Have a known hypersensitivity to any components or excipients of DZP including polyethylene glycol (PEG).
* Have received any prescription or nonprescription medicines including over-the-counter remedies and herbal and dietary supplements within 14 days or 5 half-lives of the respective drug, whichever is longer, other than acetaminophen and antihistamines.
* Current enrollment in any other drug, biological, device, or clinical study, or treatment with an investigational drug or approved therapy for investigational use within 30 days prior to Day -1, or 5 half-lives, whichever is longer.
* History of chronic, recurrent, or recent (within 6 months prior to Screening) severe infection and/or at risk for severe infection, as determined by the Investigator.
* Have symptoms consistent with SARS-CoV-2 infection, per the judgement of the Investigator, within 14 days prior to Day -1, including but not limited to fever (temperature \> 37.5 degree Celsius \[°C\]), sore throat, new and persistent cough, breathlessness, or loss of taste or smell.
* Have close contact within 14 days prior to Day -1 with a SARS-CoV-2 (+) individual. Close contact is defined as (1) being within 6 feet of an infected individual (as confirmed via laboratory assessment) for at least 15 minutes within 2 days of symptom onset or (2) being within 6 feet of an asymptomatic infected individual for at least 15 minutes within 2 days of that asymptomatic individual undergoing specimen collection for SARS-CoV-2 testing.
* Clinically significant abnormal laboratory test result values, as determined by the Investigator, at Screening or Day -1.
* Have received any live/attenuated vaccination within 6 weeks prior to Visit 2 (Day 1) or plans to receive any live/attenuated vaccination within 120 days after the dose of study treatment.

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.