The purpose of this study is to assess the safety, tolerability, and pharmacokinetics of increasing oral doses of INCB099318 in healthy adult participants, and the effect of food on pharmacokinetics.

INTERVENTION: INCB099318 is an oral tablet administered after a fast of 8 hrs in cohorts 1 through 5. In Cohort 6 subjects will be randomly assigned to treatment A or treatment B groups. Subjects in treatment A group will be dosed after fasting of 8 hrs. Subjects in treatment B group will be fed a high‐fat calorie meal 30 min before dose administration. Participants will be admitted to the clinic on the day ‐1 before study drug administration and confined through 96 hours after the dosing. In Cohort 6 subjects will return on Day 7 for admission and receive another dose of the drug on Day 8 and be confined through 96 hours after dosing. Cohort 1 ‐ 20 mg of INCB099318 or Placebo as a single dose administered orally in a fasted condition Cohort 2 – up to 40 mg of INCB099318 or Placebo as a single dose administered orally in a fasted condition Cohort 3 – up to 80 mg of INCB099318 or Placebo as a single dose administered orally in a fasted condition Cohort 4 ‐ up to 160 mg of INCB099318 or Placebo as a single dose administered orally in a fasted condition Cohort 5 – up to 320 mg of I INCB099318 or Placebo as a single dose administered orally in a fasted condition Cohort 6 – up to 160mg of INCB099318 in Fasted or Fed conditions as a single dose administered orally CONDITION: Cancer ‐ Other cancer types Solid Tumors; ; Solid Tumors PRIMARY OUTCOME: Number of treatment‐emergent adverse events with INCB099318. ; As this is the first clinical study of INCB099318, the safety profile in humans has not been established, possible symptoms or adverse effects that could occur may be immune‐related effects such as inflammation of the skin or mucosa (for example, itching, redness, rash), inflammation of the lungs, inflammation of the bowels (for example, diarrhea), endocrine (hormone) dysfunction, liver injury, and fatigue or lack of energy. AE's will be assessed by clinical examination and self reporting.[Baseline to 30 days after last dose ] Pharmacokinetic (PK) evaluation of INCB099318 (Cmax, Tmax, AUC0‐t and AUC 0‐inf) and to determine the effect of food in plasma samples[0h (pre dose), 0.5,1,2,4,6,8,12,16,24,36,48, 72, and 96h post dose ] Pharmacokinetic (PK) evaluation of INCB099318 (Cmax, Tmax, AUC0‐t and AUC 0‐inf) in the fasted state in plasma samples[0h (pre dose), 0.5,1,2,4,6,8,12,16,24,36,48, 72, and 96h post dose. ] SECONDARY OUTCOME: Additional Pharmacokinetic parameter evaluation in Plasma include ; t½, CL/F, Vz/F, Lambda‐z ; [0h (pre dose), 0.5,1,2,4,6,8,12,16,24,36,48, 72, and 96h post dose ] Pharmacokinetic evaluation of INCB099318 in Urine include ; Ae96h and CLR ; [0‐8,8‐16,16‐24,24‐36,36‐48,48‐72, and 72‐96 h post dose. ] INCLUSION CRITERIA: 1. Male or female healthy adult participants aged 18 to 55 years 2. BMI between 18.0 and 30.0 kg/m2, inclusive. Participants with a BMI up to 32.0 kg/m2 may be enrolled with the sponsor’s approval. 3. Willingness to avoid pregnancy or fathering children.