his study will explore the safety and activity of ECP treatment with UVADEX in inducing a clinical response (i.e., a CDAI decrease greater than or equal to 100 from baseline and/or a CDAI < 150) over a 12-week period in moderately active Crohn's disease (CDAI greater than or equal to 220 to < 450) patients who are refractory or intolerant to immunosuppressants and/or anti-TNF agents. This study will also assess response to continued treatment during a 12-week Extension Period in patients who have a clinical response at Week 12 of the Treatment Period and elect to participate in the Extension Period.