Phase II Clinical Study to Evaluate the Efficacy and Safety of XKH001 Injection

This is a multicenter, randomized, double-blind, placebo-parallel-controlled, two-stage design, Phase II clinical study. This study is divided into two stages. Stage 1 (Phase IIa) has a dosing duration of 24 weeks (treatment period of 28 weeks) and aims to preliminarily evaluate the efficacy, safety, PK characteristics, and immunogenicity of XKH001 Injection in trial participants with moderate to severe COPD. Stage 2 (Phase IIb) has a dosing duration of 48 weeks (treatment period of 52 weeks) and aims to further evaluate the efficacy, safety, PK characteristics, and immunogenicity of XKH001 Injection in trial participants with moderate to severe COPD. Stage 1 (Phase IIa) All trial participants who have signed the ICF will enter the Screening Period and undergo corresponding screening investigations. The screening period is a maximum of 28 days. Eligible trial participants from screening (a total of 75 participants, including 45 with a whole blood EOS count ≥300/μL and 30 with an EOS count \<300/μL) will enter the 28-week Treatment Period (dosing with investigational drug or placebo once every 4 weeks for a total of 7 doses), and their eligibility for enrollment will be reconfirmed before randomization. On Day 1, participants will be randomized in a 1:1:1 ratio to two dose groups of the investigational drug XKH001 Injection (300 mg once every four weeks \[Q4W\] or 600 mg Q4W) or placebo group, with 25 participants in each group, stratified by whole-blood EOS count (≥300/μL vs. \<300/μL) during the screening. During the treatment period, trial participants will undergo corresponding efficacy and safety assessments at specified time points (including before each dose administration). Sampling for laboratory tests must be completed before administration. COPD trial participants who complete the 28-week treatment period will enter an 8-week Follow-up Period and will return to the hospital every 4 weeks (at Weeks 32 and 36) for corresponding safety and efficacy assessments. During the study, trial participants will also have biological samples collected for PK, immunogenicity, and exploratory biomarker analysis at specified time points (including before each dose administration). All trial participants should be on stable inhaled maintenance background therapy for COPD for at least 1 month before signing the ICF, during the screening period, and until the end of the study. From the time of signing the ICF until study completion or withdrawal from the study, trial participants must record their use of background therapy in a diary card. Throughout the study, trial participants may use drugs such as Salbutamol/Levalbuterol as needed for symptom relief. Participants must record the time, reason, dosage, and frequency of use in detail in their daily diary card. Stage 2 (Phase IIb) All trial participants who have signed the ICF will enter the Screening Period and undergo corresponding screening investigations. The screening period is a maximum of 28 days. Eligible trial participants from screening will enter the 52-week Treatment Period (dosing with investigational drug or placebo Q4W for a total of 13 doses), and their eligibility for enrollment will be reconfirmed before randomization. On D1, trial participants will be randomized in a 1:1:1:1 ratio to 3 dose groups of the investigational drug XKH001 Injection (100 mg Q4W, 300 mg Q4W, 600 mg Q4W) or the placebo group, stratified by whole blood EOS count during the screening period (≥300/μL vs. \<300/μL) (tentative). During the treatment period, trial participants will undergo corresponding efficacy and safety assessments at specified time points (including before each dose administration). Sampling for laboratory tests must be completed before administration. Note: The randomization stratification factor for Stage 2 (Phase IIb) and the sample size estimation for Stage 2 (Phase IIb) will be adjusted based on the results of Stage 1 (Phase IIa). COPD trial participants who complete the 52-week treatment period will enter a 12-week Follow-up Period and will return to the hospital every 4 weeks (at Weeks 56, 60, and 64) for corresponding safety and efficacy assessments. During the study, trial participants will also have biological samples collected for PK, immunogenicity, and exploratory biomarker analysis at specified time points (including before each dose administration). All trial participants should be on stable inhaled maintenance background therapy for COPD for at least 1 month before signing the ICF, during the screening period, and until the end of the study. From the time of signing the ICF until study completion or withdrawal from the study, trial participants must record their use of background therapy in a diary card. Throughout the study, trial participants may use drugs such as Salbutamol/Levalbuterol as needed for symptom relief. Participants must record the time, reason, dosage, and frequency of use in detail in their daily diary card.