Extension Study of Safety and Tolerability of DDY391 in Participants With Moderate to Severe Psoriatic Arthritis (CDDY391A12201-extension)

The purpose of this 1-year open-label extension study is to characterize the longer-term safety and tolerability of DDY391 and to assess the durability of clinical response in participants with Psoriatic Arthritis (PsA) who have completed treatment in the CDDY391A12201 core study.

Key Inclusion Criteria: • Participants must have completed study treatment in CDDY391A12201 and must not meet any treatment discontinuation criteria of the core study at the time of OLE enrollment. Key Exclusion Criteria: * Participants taking other prohibited therapies, including but not limited to, high-potency opioids. * Received live attenuated vaccines 4 weeks prior to baseline or anticipated during the study or within 4 weeks of stopping the study drug. * Any active viral, bacterial or other infections at the time of extension study entry or history of recurrent clinically significant infection or of recurrent bacterial infections. * Women of childbearing potential unwilling to use protocol specified method of contraception. * Sexually active males unwilling to use a condom during intercourse while taking study treatment and for at least 28 days after stopping study treatment are excluded. Other protocol-defined inclusion/exclusion criteria may apply.