The purpose of this substantial protocol amendment was to provide clarification on the dose of IMP administered (including an allowance of ±10% compared to the target Dose A arm), as well as a flexible infusion rate. Sensitivity analyses were introduced to account for deviation outside the 10% target dosage and the descriptive analyses will inform about actual doses administered to the study participants. Updates to the status of the other rozanolixizumab studies had been included. The predominance of objective criteria over the investigator’s judgment had been confirmed for the assessment of CIDP relapse. The timeframe of expected use of contraception poststudy completion had been extended to 90 days in view of the probable halflife of rozanolixizumab. Exclusion Criterion had been extended to prediabetic condition. The expectation with regards to the use of cannabidiols and medicinal marijuana had been clarified in the concomitant medication section. The protocol amendment confirmed the expectation of a single rater for the Inflammatory Neuropathy Cause and Treatment (INCAT) assessment to ensure consistency of the rating during the study. The exit interview assessment had been removed from the follow-up study; this allowed UCB to confirm the adequacy of this tool using data collected in CIDP01 before extending its use in another study. Safety reporting procedures had been updated to align with most current UCB practices.

The purpose of this substantial protocol amendment was to assess the safety and key efficacy of rozanolixizumab during an optional additional treatment period (Treatment Period Part 2) of up to 52 weeks (or until an Access Program or equivalent was available for rozanolixizumab, whichever came first) on the basis of each study participant’s individual benefit-risk assessment at the end of the first 24-week Treatment Period. This amendment was the opportunity to update the new legal entity of UCB effective since Dec 2019. Additional wording pertaining study participants being able to self-administer IMP after appropriate training had been included. One exclusion criterion had been clarified. The management of hypogammaglobulinemia had been adjusted for better control. An additional interim analysis had been added at the time of lock of the parent study and another at the end of the first Treatment Period (24 weeks) matching the original timepoint of results availability.