Subcutaneous IgPro20 (Hizentra®, CSL Behring) is efficacious in CIDP with a favorable safety profile for both 0.2g/kg and 0.4g/kg doses weekly (PATH study). We conducted a 48 week multicenter, open-label prospective extension study to PATH to investigate long-term treatment.

To investigate the efficacy, safety and tolerability of weekly SCIG IgPro20 beyond 24 weeks in chronic inflammatory demyelinating polyneuropathy (CIDP).

Patients started with 0.4g/kg weekly and switched to 0.2g/kg weekly after 24 weeks. At deterioration, 0.4g/kg was re-initiated. In a later study amendment patients were started on 0.2g/kg weekly with a dose increase at disease relapse defined as a deterioration by at least 1 point in the total adjusted INCAT score compared with baseline.

Eighty-two subjects out of 172 PATH patients were enrolled. Sixty-two subjects initially received 0.4g/kg and 20 subjects 0.2g/kg weekly. Relapse occurred in 47.9% of 0.2g/kg and 9.7% of 0.4g/kg subjects. Relapse rates varied from 4.8 to 13.6% in the 0.4g/kg group and 40.0 to 50.0% in the 0.2g/kg group, depending on previous treatment in PATH. After dose reduction from 0.4g/kg to 0.2g/kg, 52% of patients worsened (32% who completed PATH without relapse on either dose) of which 89% improved after re-initiation of the 0.4g/kg dose.  Seventy-six percent of subjects (62/82) had 180 AEs. The majority (93%) of AEs in both treatment groups were mild or moderate with no related serious adverse events.