Study to Evaluate the Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of CC-99677 in Healthy Adult Japanese Participants.

Inclusion Criteria: Participants must satisfy the following criteria to be enrolled in the study: 1. Participant is ≥ 18 and ≤ 55 years of age at the time of signing the informed consent form (ICF). 2. Japanese participants must have both paternal and both maternal grandparents be ethnically Japanese. 3. Participants must adhere to protocol-specified contraception requirements. 4. Participant has a body mass index (BMI) ≥ 18 and ≤ 33 kg/m2 at screening. 5. Participant has physical exam, vital signs, clinical laboratory safety and other medical test results that are within normal limits, considered not clinically significant by the Investigator, or within other parameters specified in the protocol. Exclusion Criteria: The presence of any of the following will exclude a participant from enrollment: 1. Participant has any significant medical condition (including but not limited to neurological, gastrointestinal, renal, hepatic, cardiovascular, psychological, pulmonary, metabolic, endocrine, hematological, allergic disease, drug allergies, or other major disorders), laboratory abnormality, or psychiatric illness that would prevent the participant from participating in the study. 2. Participant has any condition including the presence of laboratory abnormalities, which places the participant at unacceptable risk if he/she were to participate in the study. 3. Participant is pregnant or breastfeeding. 4. 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). 5. Participant has used any prescribed systemic or topical medication (including but not limited to analgesics, anesthetics, etc) within 30 days prior to the first dose administration. Exceptions may apply on a case-by-case basis if considered not to interfere with the study objectives as agreed to by the Investigator and Sponsor's Medical Monitor. 6. Participant has used any non-prescribed systemic or topical medication (including vitamin/mineral supplements, and herbal medicines) within 14 days prior to the first dose administration. Exceptions may apply on a case-by-case basis if considered not to interfere with the study objectives as agreed to by the Investigator and Sponsor's Medical Monitor. 7. Participant has used CYP3A inducers and/or inhibitors (including St. John's Wort) within 30 days preceding the first dose administration. 8. Participant has any surgical or medical conditions possibly affecting drug absorption, distribution, metabolism, or excretion, e.g., bariatric procedure. Appendectomy and cholecystectomy are acceptable. Other previous surgeries may be acceptable with concurrence of the Sponsor's Medical Monitor. 9. Participant donated blood or serum within 8 weeks before the first dose administration to a blood bank or blood donation center. 10. Participant smokes \> 10 cigarettes per day, or the equivalent in other tobacco products (self-reported). 11. Participant has received immunization with a live or live attenuated vaccine within 2 months prior to the first dose administration or is planning to receive immunization with a live or live attenuated vaccine for 2 months following the last dose administration. 12. Participant has a history of Gilbert's syndrome or has laboratory findings at screening that, in the opinion of the Investigator, are indicative of Gilbert's syndrome. 13. Participant has a history of incompletely treated Mycobacterium tuberculosis (TB) infection, or has a positive QuantiFERON®-TB Gold (or equivalent) test at screening or 2 successive indeterminate QuantiFERON®-TB Gold (or equivalent) tests at screening. 14. Participants with clinical symptoms or signs (including febrile illness) suggesting active, subacute, or unresolved chronic infection. 15. Previous SARS-CoV-2 infection within 4 weeks prior to screening. a. Symptoms must have completely resolved and, based on Investigator assessment in consultation with the Sponsor's Medical Monitor, there are no sequelae that would place the participant at a higher risk of receiving IP. 16. Participant has previously been exposed to CC-99677 (e.g., in a prior clinical trial). 17. Participant has a history of photosensitivity to medications. 18. Participant is part of the study site staff personnel or a family member of the study site staff. 19. Any other exclusion criteria specified in the protocol that will be made known to participants prior to signing ICF.