The Feasibility and Safety of RK-4 Injection Bypassing Blood-brain Barrier in the Treatment of Acute Large Hemispheric Infarction Using Intracalvariosseous Injection Device

The mortality rate of large hemispheric infarction (LHI) is up to 40%-60%, while current available treatment is limited. Mainstream therapeutics include endovascular reperfusion therapy and decompressive craniectomy. But endovascular-reperfusion has limits such as short time window and hemorrhagic transformation risk, while decompressive craniectomy can reduce mortality but not infarct volume. Curative effect of intravenous injection of neuroprotective drugs is severely limited because of the blood-brain barrier. Microchannels connecting the skull bone marrow and dura may be effective drug delivery shortcuts bypassing the blood-brain barrier. Cytoprotective drug RK-4 affects dual aspects of ischemic cascade by disrupting both function of the synaptic folding post-synaptic density protein 95 (PSD-95), as well as α2-v#Aminobutyric acid type A receptor (α2-GABAAR) agonist. Phase I and Phase II clinical trials have confirmed the safety and efficacy of intravenous infusion of RK-4 in treating cerebral infarction, with the optimal dosage being 40mg. Preclinical testing proved that ICO injection of RK-4 solution 24h post rat permanent middle cerebral artery infarction reduced rat infarction volume and improved neurological function. Previously, our team has conducted the RK-4 intracalvariosseous administration in the earlier SOLUTION clinical trail through the existing neurosurgical devices. Although the safety and efficacy were preliminarily demonstrated, present administration device is not minimally invasive and requires operation in the ICU, which leads to a higher risk of the inner plate penetration. The new intracalvariosseous injection device shows promising prospective in precise control of the drilling speed and depth, and better achievement of accurate, high-efficiency and microinvasive drug delivery.

The study is a single-centered, prospective, randomized, open-label study. The purpose of this study is to investigate the feasibility and safety of RK-4 injection using intracalvariosseous injection device in acute LHI patients with contraindications of reperfusion therapy or poor outcomes.

Patients will be randomly assigned to one of the following 2 groups at 1:1 ratio.

ICO injection group: RK-4 ICO injection through intracalvariosseous injection device (using an electric bone drill to drill 3 holes (each for 1-time administration) from the outer plate of the skull without penetrating the inner cranial plate), dose was given as 32 ug/kg once a day for 3 consecutive days, as well as standard treatment and management according to the related guidelines. Conventional treatment group: Conventional treatment group will receive standard treatment and management according to related guidelines.

Face to face interviews will be made on baseline, 4±1 days after randomization, 8±1 days after randomization, 14±1 days after randomization or discharge day, and 90±7 days,180±14 days after randomization.

The primary outcomes include feasibility outcomes and safety outcomes. Feasibility Outcomes include the internal plate of skull was drilled thoroughly, drug leakage during injection, the patient refused to continue, failure for other reasons during 3 days'treatment. Safety Outcomes includes Infection events (skin infection, osteomyelitis, or intracranial infection), symptomatic and non- symptomatic intracranial hemorrhage, moderate to severe bleeding (defined by the GUSTO), hepatic insufficiency, severe renal insufficiency during the treatment, severe or extremely severe anaemia (hemoglobin <60g / L), mortality, incidence of other adverse events / serious adverse events reported.

The secondary outcomes include the effectiveness outcomes. The effectiveness outcomes include change of Glasgow Coma Scale (GCS) scores from baseline values to 14±1 days or at discharge, the change of the The National Institutes of Health Stroke Scale (NIHSS) scores from baseline to 14±1 days or at discharge, the modified Rankin Scale(mRS) 0-3 points at 90±7 days and the mRS 0-3 points at 180±14 days.

A Data and Safety Monitoring Board (DSMB) will regularly monitor safety during the study. The trial has been approved by Institutional Review Board (IRB) and Ethics Committee (EC) in Being Tiantan hospital, Capital Medical University.

Inclusion criteria

• 18≤Age≤80 years;
• First stroke or complete self-care before the onset of current stroke (mRS 0-1);
• Administration of drugs can be completed within 24h of the onset of signs and symptoms of neurological deficits (in patients with wake-up strokes or unwitnessed strokes, the time of onset is defined as the time of last normal presentation);
• Clinical symptoms, signs and imaging diagnosis of cerebral infarction in the area supplied by the middle cerebral artery, together with the following features:

• 16≤ NIHSS ≤32 points, and the sum of the scores of motor arm and motor leg is ≥6;
• Imaging suggestive of core infarct area: apparent diffusion coefficient (ADC) values <620×10-6mm2/s lesion volume on magnetic resonance imaging (MRI) diffusion-weighted imaging (DWI) sequences or cerebral blood flow (CBF) <30% of volume 70-300 ml on computed tomography perfusion imaging (CTP) or an Alberta Stroke Program Early CT Score (ASPECTS) of 0-6, with inconsistent findings, the investigator is required to make a reasoned judgement by taking into account all the information (scanning time, the imaging method that best responds to the size of infarct, etc.) and record it.
• NIHSS score not improving or progressing after reperfusion therapy and total score still ≤32.
• Informed consent signed.

Exclusion criteria

• Complications with other cerebrovascular diseases meet one of the following conditions:

• Complicated with acute cerebral hemorrhage and subarachnoid hemorrhage;
• Complicated with acute posterior circulation cerebral infarction or severe posterior circulation stenosis (>70%);
• Or imaging suggests that the area of cerebral infarction is involved bilaterally;
• The cause of the TOAST classification was considered as intracranial artery dissection, vasculitis, moyamoya disease and other etiological types.
• Hemorrhage transformation in the infarction area, hematoma area ≥30% of the infarction area, and has obvious space-occupying effect;
• Presence of clinical signs of brain herniation formation, e.g., unilateral or bilateral pupil dilation and fixation; cerebral oedema-associated loss of consciousness (NIHSS 1a > 2 points), or other loss of brainstem reflexes in the judgement of the investigator, caused by cerebral oedema or cerebral herniation formation; or other signs of instability of vital signs that are difficult to control;
• Craniotomy decompression was planned before randomization;
• Refractory hypertension (systolic > 200mmHg or diastolic > 110mmHg) or hypotension (systolic < 70mmHg or diastolic < 50mmHg) that is difficult to control with medication;
• Abnormal blood glucose before randomization (random venous blood glucose < 2.8mmol/L or > 23mmol/L);
• Presence of significant abnormal liver function markers or renal function markers prior to randomization; Note: Severe liver function abnormalities were defined as serum alanine aminotransferase (ALT), or aspartate aminotransferase (AST) > 3 times the upper limit of normal (ULN). Significant renal insufficiency is defined as eGFR less than 60 mL/min/1.73 m2 (eGFR, calculated using the CKD-EPI formula)
• Acute ST-elevation myocardial infarction (MI) and/or decompensated heart failure (meeting the New York College of Cardiology (NYHA) Heart function grades III and IV) within the past 3 months;
• Presence of contraindications to intracalvariosseous injection, e.g., skull fracture in the last 3 months, skull infection, subdural/extradural hematoma, subcutaneous hematoma, skin or subcutaneous infection of the scalp, poorly displayed skull bone marrow niches;
• Bleeding tendencies considered by the investigators to be detrimental to the procedure include, but are not limited to, platelet counts < 100×109/L, and the presence of clotting disorders such as hemophilia;
• Presence of severe or very severe anemia (hemoglobin <60 g/L) at randomization;
• Patients with severe respiratory diseases (severe chronic obstructive pulmonary disease, respiratory failure, etc.) should be corrected by intubation, tracheotomy, or ventilator;
• The subjects were considered to have developed clinically significant serious infections, including severe local infections or systemic infections;
• Diagnosed severe degenerative diseases of the central nervous system such as Alzheimer's Disease (AD), Parkinson's Disease (PD), and severe dementia of all causes, or psychiatric disorders (e.g., schizophrenia, depression, etc.);
• Subjects with a life expectancy of less than 3 months due to conditions not considered current by the investigators, such as tumors;
• Known allergy to any component of investigational process therapy drugs and contrast agents;
• Subjects who are pregnant, breastfeeding or have the possibility of becoming pregnant or plan to become pregnant;
• Subjects are unable to comply with trial protocols or follow-up requirements;
• Other circumstances deemed by the investigators to be unsuitable for enrollment (registration of reasons for inability to enroll is required);
• Have participated in other interventional clinical trials.