Real-world experience with switching from intravenous immunoglobulin to subcutaneous efgartigimod PH20 in patients with chronic inflammatory demyelinating polyradiculoneuropathy: A case series

INTRODUCTION/AIMS: In the ADHERE trial (NCT04281472), subcutaneous (SC) efgartigimod PH20 provided clinical benefit in participants with worsening chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), regardless of prior CIDP treatment, including intravenous immunoglobulin (IVIg). Real-world data for efgartigimod PH20 SC treatment, which would not require worsening CIDP, are limited. METHODS: This is a case series of four patients diagnosed with typical CIDP between 3 and 12 months before start of study, who switched from IVIg (1 g/kg every 4 weeks) to efgartigimod PH20 SC (1000 mg weekly). RESULTS: Mean age was 59.3 years. At IVIg start, mean lower limb/upper limb (LL/UL) Inflammatory Neuropathy Cause and Treatment (INCAT) scores were 3.5/2.3 (range: 3-4/2-3), and Medical Research Council (MRC) sum score was 41.0 (range: 36-44). Despite early improvements in INCAT (mean LL/UL, 2.5/1.3 [range: 2-3/1-2]) and MRC (mean 47.5 [range: 42-54]) scores with IVIg, only one patient received IVIg for 6 months; three experienced unfavorable side effects, and one switched for convenience reasons. At the start of efgartigimod PH20 SC treatment, mean LL/UL INCAT scores were 2.3/1.3 (range: 2-3/1-2) and MRC sum score was 49.0 (range: 42-54); after 6 months, there were slight improvements in INCAT (mean LL/UL, 2.0/1.0 [range: 2-2/1-1]) and MRC (mean 51.5 [range: 48-54]) scores. Side effects were minimal in three patients and were not experienced by one patient. DISCUSSION: These results suggest that patients with CIDP being treated with IVIg can benefit from switching to efgartigimod PH20 SC treatment.