A Study to Evaluate the Pharmacokinetics, Safety and Tolerability of ABBV-157 in Healthy Volunteers and in Participants With Chronic Plaque Psoriasis

This is a study to evaluate pharmacokinetics (PK), safety and tolerability of ABBV-157 in healthy volunteers and in participants with chronic plaque psoriasis, and to evaluate the efficacy of ABBV-157 in the participants with psoriasis. This study consists of two substudies. Substudy 1 is a randomized, double-blind, placebo-controlled evaluation of multiple ascending oral doses of ABBV-157 in healthy adult volunteers. Substudy 2 is a randomized, double-blind, placebo-controlled study in which participants with moderate to severe chronic plaque psoriasis will be administered multiple oral doses of ABBV-157.