Safety and Efficacy Study of Etanercept for Aneurysmal Subarachnoid Hemorrhage

Phase I Safety, Blood Brain Barrier Permeability and Potential Efficacy of Etanercept for Aneurysmal Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a special type of stroke that typically results from a ruptured intracranial aneurysm, a weakening in the wall of a blood vessel. This type of life-threatening bleeding occurs in over 3000 Canadians per year, usually in working age adults. Although this type of stroke accounts for only 5-10% of strokes, it contributes a disproportionately larger percent of overall stroke morbidity and mortality due in part to the young age of those affected. If one is fortunate enough to survive the initial bleeding episode and the subsequent surgical treatment of the aneurysm, a patient may still develop secondary strokes 3 to 14 days after the initial bleed. These delayed strokes are the most significant cause of morbidity and mortality after SAH and may be potentially preventable. Currently, there is only one medication (an anti-hypertensive) that has convincingly shown to improve outcomes after SAH. The molecular pathway causing these delayed strokes is still not clear, and this is an active area of research.

Animal studies have revealed that these delayed strokes may be caused by a pro-inflammation molecule called tumor necrosis factor alpha (TNFa). Delayed strokes were prevented experimentally by a TNFa blocker called etanercept. This clinical study, utilizing prophylactic treatment with etanercept in patients with SAH, will ensure the safety of this drug and determine its effectiveness in preventing delayed strokes.

SAH from a ruptured cerebral aneurysm has an incidence of 10 per 100,000 Canadians (over 3000 people annually). If a person survives SAH from a ruptured intracranial aneurysm, the most common complication is delayed cerebral ischemia (DCI). This is the delayed neurologic deterioration associated with angiographic vasospasm. Vasospasm refers to the arterial constriction that typically begins 3 days after SAH, is maximal 7 to 8 days later and generally resolves by 14 days. About two-thirds of patients with SAH develop vasospasm, one-third develop DCI and one-sixth of SAH patients die or sustain permanent disability from DCI, despite aggressive medical/surgical intervention.

Nimodipine, a calcium-channel antagonist, is currently the only drug to convincingly improve outcomes after SAH. Randomized multi-centre clinical trials utilizing clazosentan, an endothelin receptor antagonist, demonstrated no change in clinical outcome despite significant decrease in large vessel vasospasm. These results have shifted the research in the pathophysiology of DCI to alternative mechanisms other than large vessel vasospasm.

It is known that the presence of blood in the subarachnoid space triggers massive local and systemic inflammation, including increase in the production of a pro-inflammatory cytokine called tumor necrosis factor alpha (TNFa). We have shown in mice that global, and smooth muscle-specific knockout of TNFa prevents increased myogenic tone and reduces brain injury after SAH. Furthermore, systemic or intrathecal treatment with etanercept may prevent the increase in myogenic tone observed after SAH and may reduce brain injury. Administration of etanercept to patients with SAH is a critical step in determining the safety and potential efficacy of TNFa antagonists in SAH.

Inclusion Criteria:

• Male or female 18 to 75 years old.
• World Federation of Neurological Surgeons (WFNS) grade 2 to 4.
• Subarachnoid hemorrhage (SAH) on admission computed tomographic (CT) scan (diffuse clot present in both hemispheres or local thick SAH).
• Ruptured saccular aneurysm, confirmed by angiography (catheter or CT angiography [CTA]) and treated by neurosurgical clipping or endovascular coiling.
• External ventricular drain placed as part of routine care.
• Able to be dosed within 36 hours of injury
• Historical modified Rankin score of 0 or 1.
• Hemodynamically stable after resuscitation (systolic blood pressure [SBP] > 100 mm Hg).
• Aminotransferase levels no greater than twice the upper limit of normal, hemoglobin > 85 g/dL, platelets > 125,000 cells/mm3, serum creatinine < 177 μmol/L.
• Informed consent.

Exclusion Criteria:

• SAH due to causes other than saccular aneurysm (such as trauma or rupture of fusiform or infective aneurysm).
• Intraventricular or intracerebral hemorrhage, in the absence of SAH, or with only local, thin SAH.
• Angiographic vasospasm prior to clipping or endovascular procedure.
• Major complication during clipping or endovascular coiling, such as massive intraoperative hemorrhage, arterial occlusion or inability to clip or coil the ruptured aneurysm.
• Cardio-pulmonary resuscitation required following SAH.
• Women with a positive urine pregnancy test at screening.
• Body mass index > 35
• Severe or unstable concomitant condition or disease (e.g., known significant neurologic deficit, cancer, hematologic, or coronary disease), or chronic condition (e.g., psychiatric disorder), which, in the opinion of the investigator, would affect the assessment of the safety and tolerability of etanercept.
• Patients who have received an investigational product or participated in another clinical trial within 28 days prior to randomization or those who have already participated in the current study.
• History of hepatitis B or C, history of heart failure (etanercept may exacerbate heart failure), active infection or serious infection in the last 6 months, history of tuberculosis and history of malignancy, multiple sclerosis or history of seizures.