Inclusion Criteria:  Clinical diagnosis of PN for at least 3 months before screening. Inadequate response or intolerant to ongoing or prior PN therapy. ≥ 20 nodules on ≥ 2 different body regions at screening and Day 1. Willingness to avoid pregnancy or fathering children Further inclusion criteria apply.  Exclusion Criteria:  Have chronic pruritus due to a condition other than PN; have neuropathic and psychogenic pruritus such as but not limited to notalgia paresthetica, brachioradial pruritus, small fiber neuropathy, skin picking syndrome, or delusional parasitosis. Current use of a medication known to cause pruritus. Women who are pregnant (or who are considering pregnancy) or lactating. Medical history including thrombocytopenia, coagulopathy or platelet dysfunction, Q-wave interval abnormalities, current or history of certain infections, cancer, lymphoproliferative disorders and other medical conditions at the discretion of the investigator. Have evidence of active or latent or inadequately treated infection with Mycobacterium tuberculosis. Participants known to be infected with HIV, Hepatitis B, or Hepatitis C. Laboratory values outside of the protocol-defined ranges. Further exclusion criteria apply.