A Study to Evaluate Clazosentan on Preventing Complications Due to the Narrowing of the Blood Vessels (Vasospasm) in the Brain Caused By Bleeding On the Surface


About this study

The purpose of this study is to evaluate if clazosentan (on top of normal routine medical care) can reduce the risk of developing complications related to cerebral vasospasm and permanent brain damage as compared to normal routine medical care alone.

Participation eligibility

Participant eligibility includes age, gender, type and stage of disease, and previous treatments or health concerns. Guidelines differ from study to study, and identify who can or cannot participate. There is no guarantee that every individual who qualifies and wants to participate in a trial will be enrolled. Contact the study team to discuss study eligibility and potential participation.

Inclusion Criteria:

  • Written informed consent to participate in the study must be obtained from the subject or proxy/legal representative at any time from hospital admission to prior to initiation of any study-mandated procedure.
  • Males and females aged 18 to 70 years (inclusive, at hospital admission).
  • Subjects with a ruptured saccular aneurysm, angiographically confirmed by DSA or CTA, which has been successfully secured within 72 hours of rupture, by surgical clipping or endovascular coiling.
  • WFNS (World Federation of Neurosurgical Societies) grades 1-4 (based on Glasgow Coma Scale [GCS]) assessed after recovery from the aneurysm-securing procedure and after external ventricular drainage for hydrocephalus, if required.
  • Subjects must meet one of the two following inclusion criteria:
    • High-risk prevention: Subjects with a "thick and diffuse clot" (thick and diffuse is defined as a thick confluent clot, more than 4 mm in thickness, involving 3 or more basal cisterns) on the hospital admission CT scan, absence of cerebral vasospasm at the time of randomization, and possibility to start study drug in the ICU (or equivalent environment where all protocol assessments can be performed and the Patient Management Guidelines followed), within 96 hours after the time of the aneurysm rupture; or
    • Early treatment: Subjects without a thick and diffuse clot on the hospital admission CT scan who develop asymptomatic or minimally symptomatic moderate to severe angiographic vasospasm, within the 14-day period post-aneurysm rupture, and for whom it is possible to start study drug in the ICU (or equivalent environment where all protocol assessments can be performed and the Patient Management Guidelines followed), within 24 hours of this angiographic diagnosis.
  • Presence of a cerebral CT scan, performed at least 8 hours postaneurysm-securing procedure and within 24 hours prior to randomization, which rules out a significant (e.g., symptomatic) new or worsened cerebral infarct or re-bleeding of the repaired aneurysm.
  • A woman of childbearing potential is eligible only if the pregnancy test performed during the screening period is negative.

Exclusion Criteria:

aSAH, aneurysm-securing procedure, vasospasm:

  • Subjects with SAH due to causes other than a saccular aneurysm (e.g., trauma or rupture of fusiform or mycotic aneurysms, SAH associated with arterio-venous malformation, vertebral dissections).
  • Significant bleeding post aneurysm-securing procedure (e.g., due to intra-ventricular drain, intra-cerebral hemorrhage, epidural hematoma, vessel dissection or rupture, re-bleeding of the repaired aneurysm), based on investigator judgment.
  • Intra-or peri-aneurysm securing procedure complication requiring non-routine medical or interventional treatment such as administration of an antithrombotic or anti-platelet agent (e.g., abciximab), which is not completely resolved prior to randomization.
  • Intraventricular hemorrhage on the hospital admission CT scan, filling more than 50% of both lateral ventricles and with involvement of the 3rd and 4th ventricles. 
  • Intracerebral hemorrhage on the hospital admission CT scan, with an approximate volume of > 50 mL.
  • Presence of cerebral vasospasm at hospital admission (initial admission or transfer from another hospital) believed to be associated with a prior bleed (i.e., occurring before the bleed for which the subject is currently hospitalized). Vasospasm occurring during the aneurysm securing procedure is not an exclusion criterion.

Neurological and functional status: 

  • Subjects with a new major neurological deficit occurring post aneurysm-securing procedure which is attributable to the procedure and does not improve to pre-procedure status before randomization.
  • Subjects with a GCS score of ≤ 9 at the time of randomization and without intracranial pressure (ICP) monitoring.
  • Modified Rankin Score of 3 or higher, prior to the aSAH (i.e., due to a chronic condition).

Other clinical considerations: 

  • Subjects with total bilirubin > 2 times the upper limit of normal, and/or a known diagnosis or clinical suspicion of liver cirrhosis or moderate to severe hepatic impairment.
  • Hypotension (systolic blood pressure [SBP] ≤ 90 mmHg) at time of randomization that is refractory to treatment.
  • Unresolved pulmonary edema or significant pneumonia still present at the time of randomization, or severe hypoxia at the time of randomization in intubated subjects, defined as PaO2/FiO2 ≤ 200.
  • High sustained ICP (> 25 mmHg lasting > 20 minutes) at time of randomization, despite optimal treatment, in subjects with ICP monitoring.
  • Severe cardiac failure requiring inotropic support at the time of randomization.

Participating Mayo Clinic locations

Study statuses change often. Please contact the study team for the most up-to-date information regarding possible participation.

Mayo Clinic Location Status Contact

Jacksonville, Fla.

Mayo Clinic principal investigator

William Freeman, M.D.

Open for enrollment

Contact information:

Rosita Almira


More information


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Study Results Summary

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Supplemental Study Information

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