A Study to Evaluate the Efficacy, Safety, and Tolerability of NDI-034858 in Participants With Active Psoriatic Arthritis

This is a Phase 2b, Randomized, Multi-center, Double-Blind, Placebo-Controlled, Multiple Dose Study. Randomization to one of the treatments with NDI-034858 Dose 1, 2, 3 or placebo once daily (QD) will be based on a 1:1:1:1 scheme. The maximum study duration per participant is approximately 20 weeks, including up to 30 days for the screening period, a 12-week treatment period, and a 4-week safety follow-up period. Efficacy will be assessed using the ACR20 composite measure (including tender and swollen joint count, patient assessment of PsA pain visual analog scale (VAS), patient global PsA assessment VAS, physician global PsA assessment, HAQ-DI, and hsCRP) as well as the additional components. Efficacy for psoriasis among participants who have ≥ 3% BSA) involvement on Day 1, will be measured using PASI, PGAs, and BSA. Safety will be assessed by collecting AEs, recording vital signs, performing physical examinations, and evaluating clinical laboratory and ECGs results. Blood samples will be collected to measure plasma concentrations of NDI-034858.