Refractory CIDP: Clinical characteristics, antibodies and response to alternative treatment.

Objective: To review the clinical characteristics, antibodies, and response to alternative treatments in a cohort of patients with refractory CIDP.

Methods: We reviewed the charts of all CIDP patients seen at the Oregon Health & Science University neuromuscular clinic between 2017 and 2019. We collected demographics, clinical characteristics, antibodies, and response to treatments.

Results: Among 45 CIDP patients studied, 34 (76%) showed improvement with first-line therapy (steroids, IVIG and/or plasmapheresis) and 11 (24%) were considered refractory to first line therapy. Of the latter, 7 of 11 patients (64%) responded to alternative treatment (cyclophosphamide or rituximab). Three were refractory to all treatment. Most patients were ambulatory without aid and a few were in remission. One patient died from complications of alcoholic liver cirrhosis. Thrombosis was seen in three patients receiving IVIG. Six patients (13%) tested positive for Neurofascin (NF) antibodies. Four tested positive for NF155 IgM antibodies only and of those, one responded to IVIG, two partially responded to IVIG and one was refractory. One patient tested positive for NF155 IgG4. Another tested positive for NF155 IgG4 and NF155 IgM. Both patients with IgG4 antibodies were refractory to IVIG, one responded to rituximab and one was refractory to all treatment.

Conclusion: Less than a quarter of our CIDP patients did not respond to steroids, IVIG, and/or plasmapheresis. Most of the refractory patients responded to rituximab or cyclophosphamide. Patients with IgG4 NF antibodies were resistant to IVIG. The majority of refractory CIDP patients were seronegative and disease management relied on clinical judgement.