Infarct Growth After Intravenous Tocilizumab in Adults With Acute Ischemic Stroke Undergoing Endovascular Thrombectomy - ILLUMINATE

Inclusion Criteria: Participants are eligible to be included in the study only if all of the following criteria apply: Age 1. Participant must be above 18 years of age at the time of signing the informed consent. Type of Participant and Disease Characteristics 2. Participants who have acute ischemic stroke selected for emergency endovascular treatment according to treatment guidelines. 3. Onset of stroke symptoms (last-known-well) time to randomization time within 12 hours. 4. Large vessel occlusion in the anterior circulation (terminal internal carotid artery, M1 or M2 segment of MCA). Tandem extracranial carotid and intracranial occlusions are permitted. Sex and Contraceptive/Barrier Requirements 5. Women of childbearing potential (WOCBP) can only be included if they use a highly effective contraception method as defined in Appendix 3 of the protocol. Informed Consent 6. Participants must be capable of giving signed informed consent or consent must be given by legal representative as described in Section 10.1.2., including compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol. Exclusion Criteria: Participants are excluded from the study if any of the following criteria apply: Medical Conditions 1. Any intracranial haemorrhage during the qualifying imaging. 2. Malignancies, immunodeficiency, ongoing infection or any suspicion of acute infection. 3. Clinical history, prior imaging or clinical judgment suggesting that the intracranial occlusion is chronic, or there is a suspected intracranial dissection such that there is a predicted lack of success with endovascular intervention. 4. Systolic blood pressure \> 185 mmHg or diastolic blood pressure \> 110 mmHg at baseline, despite appropriate medical management. 5. Known thrombocytopenia (platelet count \<100 × 10³/µL), neutropenia (neutrophil count \<2.5 × 10⁹/L), or elevated liver enzymes (ALT or AST \>1.5 × the upper limit of normal \[ULN\]). 6. Known hypersensitivity to tocilizumab or any of the excipients listed in section 6.1 of the SmPC: sucrose, polysorbate 80 (E 433), disodium phosphate dodecahydrate (for pH adjustment), sodium dihydrogen phosphate dihydrate (for pH adjustment) and water for injections. Prior/Concomitant Therapy 7. Endovascular thrombectomy procedure is completed as defined by the presence of TICI 2c/3 reperfusion or completion of groin / arterial closure. 8. Patients receiving immunosuppressive drugs other than prednisolone ≤ 10 mg/day. Prior/Concurrent Clinical Study Experience 9. Known prior receipt of tocilizumab for any reason, including prior enrolment in this trial. Diagnostic Assessments 10. Contraindications to MRI. 11. Large core of established infarction (ASPECTS 0-2). Other Exclusion Criteria 12. Pregnancy/Lactation; female, with positive urine or serum beta human chorionic gonadotropin (β-hCG) test, or breastfeeding.