This 2-part study will assess the effect of formulation and food on the pharmacokinetics of Indoximod in healthy volunteers. Part 1 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. Part 2 is an open-label, randomized, 3-period, 3-way crossover study. Participants will receive single doses of Indoximod base or salt formulation, in the fasted or fed state.

Inclusion Criteria:

• Non-smoker for at least 3 months
• BMI within 18 to 30 kg/m2
• Able to speak, read, and understand English or Spanish

Exclusion Criteria:

• Clinically significant cardiac, pulmonary, hepatic or renal disease
• History of substance abuse or alcohol dependence within past 2 years
• Inability to fast for a minimum of 14 hours
• Inability to swallow large capsules/tablets
• Pending legal charges or is on probation