A Phase 2/3 Open-label Extension Study to Evaluate Long-Term Safety and Efficacy With VX-509 in Subjects With Rheumatoid Arthritis

A Phase 2/3 Open-label Extension Study to Evaluate Long-Term Safety and Efficacy With VX-509 in a Treat to Target Setting in Subjects With Rheumatoid Arthritis on Disease-Modifying Antirheumatic Drugs

This study is designed to evaluate the long-term safety and tolerability of VX-509 in subjects with active rheumatoid arthritis (RA) on DMARD therapy. This study will enroll subjects who completed a previous designated study with VX-509 (e.g., Study VX12-509-103).

VX-509 is an oral, selective Janus kinase 3 (JAK3) inhibitor being developed by Vertex. In autoimmune diseases, JAK3 is an essential component of the immune signaling cascade. This cascade ultimately contributes to abnormal immune response that results in chronic inflammation and, in the case of rheumatoid arthritis (RA), irreversible damage to cartilage and bones. Selective inhibition of JAK3 offers a new disease modifying approach to the treatment of RA.

This study will follow a "treat to target" (T2T) paradigm. T2T strategies have been followed in non-rheumatologic fields for decades. T2T trials have been conducted for RA from the late 1990's, and have substantiated the concept that treating to a target is associated with a better outcome than standard of care treatment. This has led to recommendations by experts to use T2T strategies in clinical practice.

Inclusion Criteria:

• Subjects must have completed the assigned study drug treatment phase of a previous VX-509 study (e.g., Study 103).
• Subjects must voluntarily sign and date the Study 104 informed consent document.
• Subject must be willing and able to comply with the scheduled visits, treatment plan, laboratory tests, contraceptive guidelines, and other study procedures.

Exclusion Criteria:

• Inflammatory and rheumatological disorders other than RA, where arthritis may be a prominent feature.
• History of any clinically significant illness that might, in the opinion of the investigator, confound the results of the study or pose an additional risk in administering study drug(s) to the subject
• History of tuberculosis (TB), regardless of history of antimycobacterial treatment.
• Planned surgery during the study.
• History of alcohol or drug abuse, or excessive alcohol consumption as determined by the investigator, during the previous 12 months before Day 1.
• Pregnant or nursing an infant or with a life partner who is pregnant, nursing, or planning to become pregnant