This is a single-center, randomized, double-blind, placebo-controlled, sponsor-unblinded, Phase 1 study designed to evaluate the safety, tolerability, and PK of escalating oral doses of INCB054707 in healthy male Japanese participants. Participants in each cohort will be divided into placebo or INCB054707 by a 3:1 INCB054707:placebo random assignment.

Inclusion Criteria:

• Male healthy Japanese adult participants aged 20 to 55 years with a minimum weight of 48 kg.
• Body mass index between 18.0 and 30.5 kg/m2.
• No clinically significant findings in screening evaluations.
• Ability to swallow and retain oral medication.
• Willingness to avoid fathering children

Exclusion Criteria:

• History of clinically significant cardiovascular, respiratory, renal, gastrointestinal, endocrine, hematopoietic, psychiatric, and/or neurological disease.
• History of rheumatologic/autoimmune disorders, except for minor eczema and rosacea.
• Resting pulse < 40 bpm or > 100 bpm, confirmed by repeat testing at screening.
• History or presence of an abnormal ECG before initial dose administration that, in the investigator's opinion, is clinically significant.
• Presence of a malabsorption syndrome possibly affecting drug absorption (eg, Crohn's disease or chronic pancreatitis).
• Hemoglobin, WBC, platelet, or ANC that is out of the laboratory's range unless considered clinically insignificant by the investigator at screening or check-in.
• History of malignancy within 5 years of screening, with the exception of cured basal cell or squamous cell carcinoma of the skin.
• Current or recent (within 6 months of screening) clinically significant gastrointestinal disease or surgery (including cholecystectomy, excluding appendectomy) that could affect the absorption of study drug.
• Any major surgery within 6 months of screening.
• Donation of blood to a blood bank or in a clinical study (except a screening visit) within 4 weeks of screening (within 2 weeks for plasma donation).
• Blood transfusion within 4 weeks of check-in.
• Chronic or current active infectious disease requiring systemic antibiotic, antifungal, or antiviral treatment
• Positive test for HIV and known active HBV or HCV infection or risk of reactivation of HBV or HCV.
• History of alcoholism within 3 months of screening.
• Positive breath or urine test for ethanol or positive urine screen for drugs of abuse that are not otherwise explained by permitted concomitant medications or diet.
• Current treatment or treatment within 30 days or 5 half-lives (whichever is longer) before the first dose of study drug with another investigational medication or current enrollment in another investigational drug study.
• Current treatment or treatment within 30 days or 5 half-lives (whichever is longer) before the first dose of study drug with an inducer or inhibitor of CYP3A4, P-gp, or BCRP
• Current use of prohibited medication
• Consumption of Seville oranges, grapefruit or grapefruit juice, pomelos, exotic citrus fruits, grapefruit hybrids, or fruit juices within 72 hours before the first dose of study drug.
• History of any significant drug allergy (such as anaphylaxis or hepatotoxicity) deemed clinically relevant by the investigator.
• Known hypersensitivity or severe reaction to INCB054707 or any excipients of INCB054707
• Inability to undergo venipuncture or tolerate venous access.
• Inability or unlikeliness of the participant to comply with the dose schedule and study evaluations, in the opinion of the investigator.
• History of tobacco- or nicotine-containing product use within 1 month of screening.
• Use of prescription drugs within 14 days of study drug administration or nonprescription medications/products within 7 days of study drug administration.
• Any condition that would, in the investigator's judgment, interfere with full participation in the study.
• Positive syphilis test.

Male

Incyte shares data with qualified external researchers after a research proposal is submitted. These requests are reviewed and approved by a review panel on the basis of scientific merit. All data provided is anonymized to respect the privacy of patients who have participated in the trial in line with applicable laws and regulations.

The trial data availability is according to the criteria and process described on https://www.incyte.com/our-company/compliance-and-transparency

Data will be shared after the primary publication or 2 years after the study has ended for market authorized products and indications.

Data from eligible studies will be shared with qualified researchers according to the criteria and process described in the Data Sharing section of the www.incyteclinicaltrials.com website. For approved requests, the researchers will be granted access to anonymized data under the terms of a data sharing agreement.