Two randomized, single-dose, crossover studies were carried out to assess different formulations and doses of the CCR9 receptor antagonist vercirnon in healthy subjects. US study (n = 24): a five-period crossover study in healthy US subjects to assess the bioavailability of four new GlaxoSmithKline formulations compared with a “reference” formulation. Each subject received a single 500 mg dose of each of the five vercirnon formulations in a fed state. Primary pharmacokinetic (PK) endpoints were maximum plasma concentration, (Cmax), and exposure as assessed by area under the curve (AUC). There was no significant difference in PK parameters and bioavailability between the formulations tested. Japanese study (n = 30): a four-period crossover study in healthy Japanese male subjects to assess PK and dose proportionality following single, ascending, oral doses of 250, 500, and 1,000 mg vercirnon under fasted and fed conditions. Vercirnon Cmax and AUC parameters in the fasted state increased in a less than dose proportional manner and were on average 20% higher in fed subjects compared with fasted subjects. Overall, these results support the premise that vercirnon has similar PK/safety profiles within US and Japanese populations. There was no evidence to preclude the use of the new vercirnon formulation in future studies.