KL280006

Part A study Main purpose: To evaluate the anti-itching efficacy of KL280006 injection in subjects with moderate to severe pruritus during maintenance hemodialysis. Secondary objectives: 1) To evaluate the safety of KL280006 injection in subjects with moderate to severe pruritus during maintenance hemodialysis; 2) To evaluate the pharmacokinetic characteristics of KL280006 injection in subjects with moderate to severe pruritus during maintenance hemodialysis. Part B study Main purpose: To evaluate the anti-itching efficacy of KL280006 injection at different doses in subjects with moderate to severe pruritus during maintenance hemodialysis, and to explore the optimal dose and dosing regimen for Phase III clinical studies. Secondary objectives: 1) To evaluate the safety of KL280006 injection in subjects with moderate to severe pruritus on maintenance hemodialysis; 2) To evaluate the pharmacokinetic characteristics of KL280006 injection in subjects with moderate to severe pruritus on maintenance hemodialysis; 3) To evaluate the physical dependence of KL280006 injection within 2 weeks of discontinuation after 12 weeks of administration in subjects with moderate to severe pruritus on maintenance hemodialysis; 4) To evaluate the sustained efficacy of KL280006 injection within 2 weeks of discontinuation after 12 weeks of administration in subjects with moderate to severe pruritus on maintenance hemodialysis.