This study is a Phase IIa clinical trial initiated by the researchers, which is prospective, single-center, randomized, open-label, with blinded endpoint evaluation (PROBE design). Patients were screened through the emergency stroke green channel and included if they had an onset within 9 hours, met the criteria for large artery atherosclerosis (LAA) after multimodal imaging screening, received intravenous thrombolysis, and signed informed consent to participate. The study used block randomization (block size of 4), stratified by baseline National Institutes of Health Stroke Scale (NIHSS) score (5-10 vs \>10-20) and onset-to-thrombolysis time (\<4.5 hours vs 4.5-9 hours). Intervention group: received subcutaneous injections of Ilyumumab 420 mg (three syringes) within 24 hours after thrombolysis plus standard drug therapy (including statins). Control group: received conventional statin therapy (atorvastatin 20 mg/day) after thrombolysis. All patients received standardized stroke treatment (initiating antiplatelet therapy 24 hours after thrombolysis) and standardized management of blood pressure and blood glucose. NIHSS scores were assessed every 12 hours within 72 hours post-thrombolysis, and then daily thereafter, to evaluate the effectiveness of combined therapy in reducing early neurological deterioration (END). Blinding: The study is open-label. An independent Clinical Endpoint Committee (CEC) was established, and all clinical endpoint events (END assessment, 90-day mRS scores) were evaluated in a blinded manner by experts who were completely unaware of group assignments.