Adverse change in the risk/benefit.

The purpose of this study is to assess the safety and tolerability of BMS-986421 in healthy adult participants.

Inclusion Criteria:

• Participants are required to remain in the clinical facility from Day -1 (Part 1) or Day -2 (Part 2) until clinic discharge.
• A negative test for COVID-19, which will be performed in the manner mandated by the clinical site where this study is being conducted, at screening and admission.
• All female participants, Women of Childbearing Potential (WOCBP) and women not of childbearing potential, must have a negative highly sensitive serum pregnancy test (minimum sensitivity 25 IU/L or equivalent units of human chorionic gonadotropin (HCG)) at screening and on Day -1 (or Day -2 for Part 2).

Exclusion Criteria:

• Participant was exposed to an investigational drug (new chemical entity) within 30 days preceding the first dose administration, or 5 half-lives of that investigational drug, if known (whichever is longer).
• Vaccination or plans for vaccination with non-live vaccines within 30 days before Day -1 (for Day -2 for Part 2) until the follow-up phone call.
• Donation of blood or blood transfusion within 8 weeks of first study intervention administration.

BMS will provide access to individual anonymized participant data upon request from qualified researchers, and subject to certain criteria. Additional information regarding Bristol Myers Squibb's data sharing policy and process can be found at: https://www.bms.com/researchers-and-partners/clinical-trials-and-research/disclosurecommitment.html