• 3) Time to disease progression
• 1) Survival
• 2) Disease improvement

Chronic inflammatory demyelinating polyneuropathy is disease believed to be due to immune cells, cells which normally protect the body, but are now attacking the nerves in the body. As a result, the affected nerves fail to respond, or respond only weakly, to stimuli causing numbing, tingling, pain, and progressive muscle weakness. The likelihood of progression of the disease is high. This study is designed to examine whether treating patients with high dose cyclophosphamide (a drug which reduces the function of the immune system) and ATG (a protein that kills the immune cells that are thought to be causing your disease), followed by return of the previously collected blood stem cells will stop the progression of CIDP. Stem cells are undeveloped cells that have the capacity to grow into mature blood cells, which normally circulate in the blood stream. The purpose of the high dose cyclophosphamide and ATG is to destroy the cells in the immune system. The purpose of the stem cell infusion is to evaluate whether this treatment will produce a normal immune system that will no longer attack the body.

Inclusion Criteria:

1. Age 65 years old or less at the time of pretransplant evaluation.
2. Definite or probable CIDP according to the criteria of the Ad Hoc Subcommittee of the American Academy of Neurology AIDS Task Force (SEE APPENDIX).
3. Failure to respond to, or an incomplete response to, or relapse to at least 3 months of conventional treatment consisting of corticosteroids (equivalent dosage of prednisone 1.0/mg/day to start), and IVIG or plasmapheresis and patients also must have failed one or more of the following: cyclophosphamide, tacrolimus, azathioprine, cyclosporin A, methotrexate, mycophenolate mofetil, TNF inhibitors (i.e. etanercept) or any other immunosuppressive drugs or immune modulators.

4. Failure to therapy defined by (one of the following) (not caused by unrelated conditions):

   1. Persistent muscle weakness Grade 3/5 or worse (MRC) in at least one muscle in two limbs (e.g. both deltoids, both hip flexors) or one limb.
   2. Persistent dysphagia documented by either aspiration or insufficient clearing on videofluoroscopic examination.
   3. Persistent incapacitating sensory loss (e.g. gait ataxia, falls > 1/month)

Exclusion Criteria:

1. Any evidence of another cause for neuropathy.
2. Nerve pathology (if available) not consistent with CIDP.
3. Poor performance (PS) status (ECOG >2) at the time of entry, unless decline of PS is due to the disease itself.

4. Significant end organ damage such as (not caused by CIDP):

   1. LVEF <40% or deterioration of LVEF during exercise test on MUGA or echocardiogram.
   2. Untreated life-threatening arrhythmia.
   3. Active ischemic heart disease or heart failure.
   4. DLCO <40% or FEV1/FEV < 50%.
   5. Serum creatinine >2.5 or creatinine clearance <30ml/min.
   6. Liver cirrhosis, transaminases >3x of normal limits or bilirubin >2.0 unless due to Gilbert disease.
5. HIV positive.
6. Uncontrolled diabetes mellitus, or any other illness that in the opinion of the investigators would jeopardize the ability of the patient to tolerate aggressive treatment.
7. Prior history of malignancy except localized basal cell or squamous skin cancer. Other malignancies for which the patient is judged to be cured by local surgical therapy, such as (but not limited to) head and neck cancer, or stage I or II breast cancer will be considered on an individual basis.
8. Positive pregnancy test, inability or unwillingness to pursue effective means of birth control, or failure to willingly accept or comprehend irreversible sterility as a side effect of therapy.
9. Psychiatric illness or mental deficiency making compliance with treatment or informed consent impossible.
10. Inability to give informed consent.
11. Major hematological abnormalities such as platelet count less than 100,000/ul or ANC less than 1000/ul.
12. Failure to collect at least 2.0 x 106 CD34+ cells by apheresis and, if necessary, bone marrow harvest is a contraindication to treatment, i.e., receiving the conditioning regimen.