Alemtuzumab in Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIPD)

This is an open-label multi-center trial of alemtuzumab in the treatment of Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP). The study will have 4 phases. Approximately 16 eligible participants will receive at least one cycle of alemtuzumab (5 days of drug infusion). Additional cycles of alemtuzumab (3 days of drug infusion) may be provided at the discretion of the participants' treating physician such as if clinical worsening occurs. Phase 1: Screening Participants meeting the inclusion and exclusion criteria and having signed the informed consent document will enter the screening phase and undergo baseline evaluations. Phase 2: Drug Infusion Participants will receive alemtuzumab by infusion using a standardized protocol. Participants will be maintained on their prior CIDP therapy during the drug infusions and then followed at regular intervals. Phase 3. Alteration of CIDP therapy CIDP therapy may be altered at the discretion of the treating physician - either taper, discontinuation, or increase of current or additional medications. For those participants on chronic corticosteroid therapy, following pulse IV methylprednisolone and alemtuzumab cycle, corticosteroids will be tapered as rapidly and as far as possible according to according to the investigator's discretion. While the aim will be to discontinue corticosteroids, it is recognized that some participants will have a suppressed pituitary-adrenal axis and complete discontinuation may not be possible. Phase 4: Extended Follow-up Each participant will be followed per protocol for a minimum of 36 months. All participants will undergo safety assessments and monitoring for at least 36 months after the last cycle of alemtuzumab. Additional cycles of alemtuzumab may be provided at the discretion of the participants' treating physician with at least a 12 month interval between cycles. NUMBER OF PARTICIPANTS: Approximately 16 participants will join this study.