This 2-part study will assess the effect of formulation and food on the pharmacokinetics of Indoximod in healthy volunteers. Part 1 is an open-label, 3-period, 6-sequence study. Participants will receive single doses of Indoximod base or salt formulation, in the fasted or fed state. Part 2 is a randomized single ascending dose study of indoximod salt formulation to characterize the PK profile and determine the safety and tolerability of each dose in healthy male volunteers.

Inclusion Criteria:

• Healthy male subjects 18 to 55 years of age, inclusive.
• Body mass index (BMI) of 18.0 to 30.0 kg/m2, and a minimum weight of 50.0 kg.
• Non-smoker for at least 3 months prior to Screening.
• Male subjects with female sexual partners of childbearing potential must be using and willing to continue using medically acceptable contraception
• Signed and dated written informed consent

Exclusion Criteria:

• History or presence of any clinically significant abnormality, illness, or disease which, in the opinion of the investigator, may either put the subject at risk because of participation in the study or influence the validity of the results of the study.
• Subjects with autoimmune conditions, inflammatory bowel disease, rheumatoid arthritis, and/or subjects who have undergone an organ transplant.
• Self-reported history of substance or alcohol dependence within the past 2 years, and/or has ever participated or plans to participate in a substance or alcohol rehabilitation program to treat their substance or alcohol dependence.
• Any medical/surgical procedure or trauma within 4 weeks of the first study drug administration or planned within 1 month of study completion.
• Positive urine drug screen.
• Positive breath alcohol test.
• Evidence of clinically significant hepatic or renal impairment
• Inability to fast for a minimum of 14 hours.
• Inability to swallow large capsules/tablets.
• Positive for hepatitis B, hepatitis C, or human immunodeficiency virus (HIV).
• Donation or loss of more than 500 mL whole blood within 1 month preceding entry into the Treatment phase and throughout the study.
• Difficulty with venous access or unsuitable or unwilling to undergo catheter insertion.
• History of severe allergic reaction (including anaphylaxis) to any substance, or previous status asthmaticus.
• Treatment with an investigational drug within 5 times the elimination half-life, if known (eg, a marketed product), or within 30 days (if the elimination half-life is unknown) prior to first drug administration or is concurrently enrolled in any research judged not to be scientifically or medically compatible with this study.