Open-Label Extension Study of GSK1605786A

This is a multi-centre, open-label extension study to assess the long-term safety, tolerability and effectiveness of GSK1605786A in subjects with Crohn's disease. Subjects will enter the study via one of three routes: 1. completion of the placebo-controlled induction study, CCX114151, without achieving clinical response (CDAI decrease of at least 100 points) or clinical remission (CDAI score less than 150) at Week 12 or completion of any other GSK-sponsored induction study as designated by the sponsor 2. completion of maintenance study CCX114157 at Week 52 3. withdrawal from maintenance study CCX114157 due to worsening of Crohn's disease and requiring a treatment change. The primary objective is to evaluate the safety of GSK1605786A, as assessed by recording of adverse events, clinical laboratory parameters, vital signs and electrocardiogram. Secondary objectives will include assessments of effectiveness of long-term treatment with GSK1605786A. Health outcomes assessments will include changes in Inflammatory Bowel Disease Questionnaire (IBDQ), SF-36v2, EQ-5D, Work and Productivity Activity Impairment-Crohn's Disease (WPAI-CD) and disability. It is estimated that approximately 800 subjects will be enrolled in total. All subjects will enter the study at baseline (Week 0) and commence oral treatment with GSK1605786A 500 mg twice daily. The study will be conducted for 108 weeks. Once the results of the induction study CCX114151 are known, the risk-to-benefit ratio will be re-assessed and the study duration may be amended. Study assessments for Crohn's disease will be performed every 12 weeks through Week 108. At week 12, the investigator will make a determination of whether the subject is receiving clinical benefit, and subjects who are not receiving clinical benefit must be withdrawn. More frequent blood draws are required for liver function testing only; every 2 weeks for the first 12 weeks, then every 4 weeks up to Week 52, and every 12 weeks after Week 60 for the duration of the study.