Preventive Effect of Clazosentan against Cerebral Vasospasm after Clipping Surgery for Aneurysmal Subarachnoid Hemorrhage in Japanese and Korean Patients.

backgroundClazosentan has been explored worldwide for the prophylaxis of cerebral vasospasm after aneurysmal subarachnoid hemorrhage (aSAH). In a dose-finding trial (CONSCIOUS-1) conducted in Israel, Europe, and North America, clazosentan (1, 5, and 15 mg/h) significantly reduced the incidence of cerebral vasospasm, but its efficacy in Japanese and Korean patients was unknown. We conducted a double-blind comparative study to evaluate the occurrence of cerebral vasospasm in Japanese and Korean patients with aSAH.

methodsThe aim of this multicenter, double-blind, randomized, placebo-controlled, dose-finding phase 2 clinical trial, was to evaluate the efficacy, pharmacokinetics, and safety of clazosentan (5 and 10 mg/h) against cerebral vasospasm after clipping surgery in Japanese and Korean patients with aSAH. Patients aged between 20 and 75 years were administered the study drug within 56 h after the aneurysm rupture and up to day 14 post-aSAH. The incidence of vasospasm, defined as an inner artery diameter reduction of major intracranial arteries ≥34% based on catheter angiography, was compared between each treatment group. Cerebral infarction due to vasospasm at 6 weeks and patients' outcome at 3 months was also compared.

resultsAmong 181 enrolled patients, 158 completed the study and were analyzed. The incidence of vasospasm up to day 14 after aSAH onset was 80.0% in the placebo group (95% CI 67.0-89.6), 38.5% in the 5 mg/h clazosentan group (95% CI 25.3-53.0), and 35.3% in the 10 mg/h clazosentan group (95% CI 22.4-49.9), indicating that the incidence of vasospasm was significantly reduced by clazosentan treatment (placebo vs. 5 mg/h clazosentan, p < 0.0001; placebo vs. 10 mg/h clazosentan, p < 0.0001). The occurrence of cerebral infarction due to vasospasm was 20.8% in the placebo group (95% CI 10.8-34.1), 3.8% in the 5 mg/h clazosentan group (95% CI 0.5-13.2), and 4.2% in the 10 mg/h clazosentan group (95% CI 0.5-14.3), indicating that clazosentan significantly reduced the occurrence of cerebral infarctions caused by vasospasm (placebo vs. 5 mg/h clazosentan, p = 0.0151; placebo vs. 10 mg/h clazosentan, p = 0.0165). The overall incidence of all-cause death and/or vasospasm-related morbidity/mortality was significantly reduced in the 10 mg/h clazosentan group compared with the placebo group (p = 0.0003).

conclusionThese results suggest that clazosentan prevents cerebral vasospasm and subsequent cerebral infarction, and could thereby improve outcomes after performing a clipping surgery for aSAH in Japanese and Korean patients.