An Open-label, Long-term Extension Study With Filgotinib in Active Psoriatic Arthritis.

A Multicenter, Open-label, Long-term Extension Safety and Efficacy Study of Filgotinib Treatment in Subjects With Moderately to Severely Active Psoriatic Arthritis.

This is a Phase 2, multicenter, open-label, single arm, Long Term Extension (LTE) safety, tolerability and efficacy study of filgotinib in subjects with moderately to severely active PsA. It is estimated that approximately 105 subjects will be rolled-over after they have completed the 16 weeks of double-blind treatment in core study GLPG0634-CL-224. Subjects will be administered filgotinib in this study until filgotinib is registered for PsA or until Week 304, whichever occurs first. The LTE study is concluded with a follow-up visit approximately 4 weeks after the last intake of study treatment.

Inclusion Criteria:

• Male or female subjects who are ≥18 years of age, having completed the 16 weeks of treatment in the qualifying core study GLPG0634-CL-224 and who may benefit from filgotinib long-term treatment according to the investigator's judgment.
• Male and female subjects of childbearing potential who engage in heterosexual intercourse must agree to continue to use highly effective methods of contraception as described in the protocol.
• Able and willing to sign the informed consent form (ICF), as approved by the Independent Ethics Committee (IEC) and agree to the schedule of assessments.

Exclusion Criteria:

• Subjects who are deemed not to be benefitting from the study drug based upon lack of improvement or worsening of their symptoms. Local guidelines for subject treatment need to be followed.
• Persistent abnormal laboratory values associated with the use of the study drug (including and not limited to hematology, liver and renal function values), according to the investigator's clinical judgment.
• Subjects who discontinued the qualifying core study GLPG0634-CL-224 due to safety or tolerability issues.
• Subjects who require immunization with live/live attenuated vaccine.
• Diagnosis of rheumatic autoimmune disease or inflammatory joint disease other than psoriatic arthritis, except for Sjögren's syndrome.
• Subjects with symptoms suggestive of uncontrolled hypertension, congestive heart failure, uncontrolled diabetes, cerebrovascular accident, myocardial infarction, unstable angina, unstable arrhythmia or any other cardiovascular condition since the inclusion to the GLPG0634- CL-224 study.
• Subjects with symptoms suggestive of gastrointestinal tract ulceration and/or active diverticulitis since the inclusion to the GLPG0634-CL-224 study.
• Subjects with symptoms suggestive of possible lymphoproliferative disease including lymphadenopathy or splenomegaly since the inclusion to the GLPG0634-CL-224 study.
• Subjects with symptoms suggestive of malignancy since the inclusion to the GLPG0634-CL-224 study.