Transitioning from efgartigimod to tacrolimus in chronic inflammatory demyelinating polyneuropathy: a prospective case series.

To describe the clinical outcomes of transitioning from efgartigimod to tacrolimus in chronic inflammatory demyelinating polyneuropathy (CIDP) patients. Six patients who completed the ADHERE trial and maintained clinical stability during the open-label extension phase (≥30 weeks of weekly efgartigimod) were transitioned to oral tacrolimus following efgartigimod discontinuation and were followed at 3-month intervals for 12 months. Clinical effectiveness was assessed utilizing the Inflammatory Neuropathy Cause and Treatment (INCAT) disability scale, centile Inflammatory Rasch-built Overall Disability Scale (cI-RODS), Medical Research Council (MRC) sum score (0-60), grip strength, 3m-Timed Up and Go Test (TUG) as well as electrophysiological examination. Safety was evaluated by monitoring adverse events. Peripheral T and B lymphocytes, interleukins and immunoglobulin levels were measured at each visit, and tacrolimus trough levels were monitored during follow-up. Three of six patients completed 12-month follow-up and achieved clinical stability or improvement by month 12. Two discontinued within three months due to poor clinical response and regained improvement following transition back to intravenous immunoglobulin or efgartigimod. One expressed a preference for traditional Chinese medicine and was lost to follow-up. No severe adverse events were observed. Oral tacrolimus may be a potential maintenance approach for sustaining clinical stability in a subset of CIDP patients stabilized on efgartigimod. Longitudinal naive B-cell monitoring warrants further investigation as a potential early indicator of clinical instability during tacrolimus maintenance therapy.