Study to Assess the Efficacy, Safety, and Tolerability of Vixarelimab in Reducing Pruritus in Prurigo Nodularis

This is a Phase 2a/b randomized, double-blind, placebo-controlled study to investigate the efficacy, safety, tolerability, PK and immunogenicity of Vixarelimab administered subcutaneously (SC) in subjects with prurigo nodularis experiencing pruritus. Phase 2a portion: Forty-nine subjects with moderate to severe PN experiencing moderate to severe pruritus are treated in the Phase 2a portion of the study. At Baseline, subjects are randomized 1:1 to receive double-blind (DBL) vixarelimab or placebo: vixarelimab 720 mg loading dose followed by 360 mg every week; placebo loading dose followed by placebo every week. The treatment period is 8 weeks or 16 weeks (treatment duration was reduced from 16 weeks to 8 weeks in a protocol amendment \[Protocol Version 3\]). Phase 2b portion: The Phase 2b study consists of a 4-week Screening Period and a 16-week Double-Blind Period, followed by a 36-week Open-Label-Extension (OLE) Period. Approximately 180 subjects with PN, experiencing severe pruritus, are randomized (at 1:1:1:1 ratio) into one of 4 arms (3 active arms and one placebo arm). A total of 4 doses of study drug are administered during the Double-Blind Period to measure the efficacy, safety, and PK of Vixarelimab. After the Double-Blind Period, all subjects have the option to receive vixarelimab during the OLE Period to evaluate the long-term safety and PK.