This will be an open-label, uncontrolled study which will enroll subjects from Phase 4 of Study 31-07-246 and Phase 3 of Study 31- 07-247 and new subjects not participating in Studies 246/247. The treatment history of subjects prior to enrollment in the open-label study will vary according to the design of the pivotal double-blind study (i.e., 31-07-246 or 31-07-247).