FASTEST Trial Shows Mixed Results for Factor VIIa in Acute Intracerebral Hemorrhage, Signals Promise in Early Treatment Subgroups
Key Insights
The phase III FASTEST trial found that recombinant factor VIIa (search) reduced hematoma growth when given within 2 hours of intracerebral hemorrhage (search) onset but failed to improve overall functional outcomes.
Treatment significantly increased life-threatening thromboembolic complications (search) (4.6% vs 1.3%) while showing promising signals in patients treated within 90 minutes or those with positive spot signs on CT angiography.
FASTEST Part 2 is now underway, focusing specifically on these higher-response subgroups to evaluate whether ultra-early hemostatic therapy can achieve meaningful clinical benefits.
The phase III FASTEST trial has delivered mixed results for recombinant factor VIIa (search) (rFVIIa) as a hemostatic therapy for acute intracerebral hemorrhage (search) (ICH (search)), showing biological efficacy in reducing bleeding but failing to translate into improved functional outcomes in the overall population. However, subgroup analyses revealed promising signals that are now driving a targeted follow-up study.
Primary Results Show Biological Effect Without Clinical Benefit
The international trial, conducted across 103 sites in six countries, randomized 626 patients with spontaneous ICH (search) to receive intravenous rFVIIa at 80 μg/kg (maximum 10 mg) or placebo within 2 hours of stroke (search) onset. The mean time from ICH onset to drug administration was 100 minutes, achieved through innovative approaches including mobile stroke units.
While rFVIIa successfully reduced hematoma expansion—with mean ICH (search) volume increases of 1.85 mL compared to 5.53 mL for placebo at 24 hours—this biological effect did not translate into functional improvement. The primary outcome of modified Rankin Scale scores at 180 days showed no significant difference between treatment groups (adjusted common OR 1.09; 95% CI 0.79-1.51).
"The enhanced biological effect in stopping bleeding in these two subgroups was associated with efficacy at 90 days and borderline efficacy at 180 days," said Joseph Broderick, MD, from the University of Cincinnati, who presented the findings at the International Stroke (search) Conference.
Safety Profile Reveals Increased Thromboembolic Risk
The treatment carried a significant safety signal, with life-threatening thromboembolic complications (search) occurring in 4.6% of rFVIIa-treated patients versus 1.3% of placebo recipients during the first four days (relative risk 3.41; 95% CI 1.14-10.15). Additional safety concerns included higher rates of myocardial injury (search) without acute coronary syndrome (14.9% vs 10.1%) and acute cerebral infarction (search) (5.5% vs 3.7%) in the active treatment group. Mortality rates remained similar between groups at 180 days (6.1% vs 7.4%).
Subgroup Analyses Identify Promising Treatment Windows
Despite the overall neutral results, two key subgroups showed both enhanced biological effects and signals of clinical benefit. Patients treated within 90 minutes of ICH (search) onset demonstrated greater hematoma control, with a mean treatment difference in ICH plus intraventricular hemorrhage volume of -7.56 mL compared to -4.30 mL for those treated after 90 minutes.
Similarly, patients with a positive spot sign on CT angiography—a biological marker of ongoing bleeding—showed substantial benefit, with a mean difference of -14.14 mL in hematoma growth compared to only -2.67 mL for those without spot signs. Among spot sign-positive patients, major hemorrhage enlargement (>12.5 mL) occurred in 14.0% of rFVIIa-treated patients versus 32.4% of placebo recipients, representing a 38% absolute difference in moderate and major hemorrhage enlargement.
Strategic Pivot to Targeted Population
Based on these findings, investigators have launched FASTEST Part 2, which specifically enrolls patients most likely to benefit from hemostatic therapy. The follow-up trial targets patients with positive spot signs treated within 120 minutes or any patient treated within 90 minutes, regardless of spot sign status.
"We think we now have a very clear road map to the first hemostatic therapy for intracerebral hemorrhage (search)," Broderick noted, emphasizing the strategic focus on populations where biological and clinical signals were strongest.
Steven Greenberg, MD, PhD, from Massachusetts General Hospital, who commented on the study, noted that the subgroup findings appear scientifically sound rather than data-driven. "The analysis was very thoughtful," he said, adding that finding benefit in patients treated within 90 minutes and those with positive spot signs "makes sense because you're getting the process when it's most active or earliest."
Clinical Implications and Future Directions
The FASTEST results highlight both the promise and challenges of hemostatic therapy for ICH (search). While the overall trial was negative, the identification of specific subgroups with enhanced biological and potential clinical responses provides a foundation for more targeted therapeutic approaches.
FASTEST Part 2 aims to recruit up to 350 participants over approximately three and a half years, leveraging emergency research consent pathways and mobile stroke (search) units to achieve ultra-early treatment. The trial's goal of treating half of enrolled patients within 90 minutes reflects the critical importance of timing in hemostatic intervention.
The study's innovative logistics, including the use of mobile stroke (search) units and achieving treatment within 2 hours for all patients, were described as "remarkable" by Greenberg, who noted that such demanding protocols demonstrate the feasibility of ultra-early intervention strategies in acute stroke care.