A Study of Zasocitinib in Adults With Psoriatic Arthritis Who Have or Have Not Been Treated With Biologic Medicines

Percentage of Participants Achieving American College of Rheumatology 20 (ACR20) Response at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: At Week 16]

Percentage of Participants Achieving Minimal Disease Activity (MDA) at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: At Week 16]

Percentage of Participants Achieving PASI-75 Response (in Participants With a Baseline >=3% BSA) at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: Baseline, at Week 16]

Percentage of Participants Achieving ACR50 Response at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: At Week 16]

Change From Baseline in the HAQ-DI Score at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: Baseline, at Week 16]

Percentage of Participants Achieving ACR70 Response at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: At Week 16]

Change From Baseline in the Short Form-36 Health Survey Version 2.0 (SF-36 v2.0) Physical Component Summary (PCS) Score at Week 16 for Zasocitinib Dose A Compared to Placebo [Time Frame: Baseline, at Week 16]

Change From Baseline in the Functional Assessment of Chronic Illness Therapy (FACIT)- Fatigue Score at Week 16 for Zasocitinib Dose A Compared to Placebo [Time Frame: Baseline, at Week 16]

Percentage of Participants Achieving LEI =0 (in Participants With a Baseline LEI >=1) at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: Baseline, at Week 16]

Change From Baseline in Individual Components of ACR Response at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: Baseline, at Week 16]

Percentage of Participants Achieving Leeds Dactylitis Index (LDI) =0 (in Participants With a Baseline LDI >=1) at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: Baseline, at Week 16]

Percentage of Participants Achieving PASI-75 Response (in Participants With a Baseline >=3% BSA) at Week 8 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: Baseline, at Week 8]

Percentage of Participants Achieving PASI-90 Response (in Participants With a Baseline >=3% BSA) at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: Baseline, at Week 16]

Percentage of Participants Achieving PASI-100 Response (in Participants With a Baseline >=3% BSA) at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: Baseline, at Week 16]

Percentage of Participants Achieving ACR50 and PASI-100 Response (in Participants With a Baseline >=3% BSA) Simultaneously at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: Baseline, at Week 16]

Percentage of Participants Achieving sPGA Response of Clear (0) or Almost Clear (1) With >=2-Point Decrease From Baseline (in Participants With a Baseline sPGA >=2) at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: Baseline, at Week 16]

Percentage of Responders Achieving Minimal Clinically Important Differences (Reduction of >=0.35 From Baseline) in HAQ-DI Score From Baseline at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: Baseline, at Week 16]

Change From Baseline in the SF-36 v2.0 Mental Component Summary (MCS) Score at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: Baseline, at Week 16]

Change From Baseline in Psoriatic Arthritis Impact of Disease-12 Items (PsAID-12) Total Score at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: Baseline, at Week 16]

Change From Baseline in Disease Activity Index for Psoriatic Arthritis (DAPSA) Score at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: Baseline, at Week 16]

Change From Baseline in Disease Activity Score-28 (DAS28) (C-Reactive Protein) Score at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: Baseline, at Week 16]

Change From Baseline in Physician's Global Assessment of Fingernail Psoriasis (PGA-F) Score in Participants With Psoriatic Nail Involvement (PGA-F Greater than [>] 0) From Baseline at Week 16 for Zasocitinib Dose A and B Compared to Placebo [Time Frame: Baseline, at Week 16]

Change From Baseline in the SF-36 v2.0 PCS Score at Week 16 for Zasocitinib Dose B Compared to Placebo [Time Frame: Baseline, at Week 16]

Change From Baseline in the FACIT- Fatigue Score at Week 16 for Zasocitinib Dose B Compared to Placebo [Time Frame: Baseline, at Week 16]