The purpose of the study is to determine whether an investigational compound, ALX-0600, is safe and effective in treating Crohn's Disease.

The study is sixteen weeks in duration and there are twelve weeks of once-daily injections into your abdomen or thigh. There are a total of five visits.

Inclusion Criteria:

• Subjects must have completed participation in the Pilot Active Crohn's Disease Study.

• Subjects must continue to meet all inclusion criteria for Pilot Active Crohn's Disease Study with the following exceptions:

  • CDAI score greater than 220
  • Stool samples not required
  • C-reactive protein levels are not an exclusion criterion

Exclusion Criteria:

• Subject must continue to meet all exclusion criteria for Pilot Active Crohn's Disease Study with the following exceptions:

  • Participation in a clinical study of an experimental drug or device within 30 days before signing consent.