Abstract
Background
Fibrinogenase for injection is an effective antithrombotic agent for eligible patients with acute ischaemic stroke (AIS), but evidence regarding its treatment effects remains limited. This study aimed to evaluate the efficacy and safety of fibrinogenase for injection in patients with AIS who did not receive reperfusion therapies.
Methods
A multicentre, randomised, double-blind, placebo-controlled clinical trial was conducted at 12 hospitals in China. Inclusion criteria comprised patients aged 18–85 years with a diagnosis of AIS, an NIH Stroke Scale (NIHSS) score of 4 to 25 and within 72 hours of symptom onset. Eligible patients were randomly allocated in a 1:1 ratio to receive fibrinogenase for injection or placebo. The primary efficacy endpoint was the modified Rankin Scale (mRS) Score at 90 days after randomisation.
Results
Among 235 patients with AIS who were randomised, 233 were included in the intention-to-treat population (117 in the fibrinogenase for injection group and 116 in the placebo group). The mRS score at 90 days after randomisation was significantly lower in the fibrinogenase group (1 (0–2)) than in the placebo group (2 (1–3)), with a favourable shift in the distribution of mRS scores (OR 2.38, 95% CI 1.49 to 3.85; p<0.001). A significantly lower median NIHSS score at 90 days was observed in the fibrinogenase group (1 (0–2)) compared with the placebo group (2 (1–4)) (OR 1.95, 95% CI 1.23 to 3.10; p<0.001). The incidence of haemorrhagic events and mortality during treatment was comparable between the two groups.
Conclusions
In patients with AIS, treatment with fibrinogenase for injection was associated with improved 90-day functional outcomes compared with placebo. This clinical benefit was particularly evident among those who were randomised within 48 hours of symptom onset and in those with mild to moderate stroke due to large artery atherosclerosis or small artery occlusion.
Trial registration number
ChiCTR2100042526; Chinese Clinical Trial Registry.
Keywords: Stroke, Ischemic Stroke, Cerebral Infarction, Clinical Trial
WHAT IS ALREADY KNOWN ON THIS TOPIC
Fibrinogenase, a fibrinolytic enzyme derived from the venom of Changbai Mountain viper (Gloydius blomhoffi siniticus), directly targets thrombus precursor protein. Previous studies have indicated its potential efficacy in improving functional outcomes of patients with acute ischaemic stroke (AIS).
WHAT THIS STUDY ADDS
In this randomised clinical trial comprising 235 consecutive AIS patients enrolled within 72 hours of stroke onset, treatment with fibrinogenase for injection was associated with improved 90-day functional outcomes compared with placebo, especially in those randomised within 48 hours of symptom onset and with mild-to-moderate stroke due to large artery atherosclerosis or small artery occlusion.
HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY
This study provides evidence that fibrinogenase for injection may present a safe and effective treatment for improving functional outcomes of selected patients with AIS without reperfusion therapies.
Introduction
Globally, stroke has become the second leading cause of mortality and the third leading cause of disability.1 Intravenous thrombolysis (IVT) and mechanical thrombectomy (MT), the main reperfusion approaches, have been proven to significantly improve functional recovery following acute ischaemic stroke (AIS).2 3 In recent years, with the publication of several landmark clinical trials, the therapeutic window for IVT and MT has been expanded to 24 hours in selected patients.4 5 However, even with expanded time window and indications of reperfusion therapies, only 5.64% and 1.45% patients with AIS, respectively, received IVT and MT in China.6 Therefore, there is an urgent need to explore new therapies for patients with AIS, especially those without reperfusion therapies.
Fibrinogenase is a fibrinolytic enzyme derived from the venom of Changbai Mountain viper (Gloydius blomhoffi siniticus). As a zinc metalloproteinase, it primarily targets thrombus precursor protein (TpP), specifically degrading soluble fibrin monomers and their polymers.7 By degrading TpP into small soluble fragments that are subsequently broken down and cleared from the bloodstream, fibrinogenase induces a systemic defibrinating effect.8 Furthermore, fibrinogenase enhances the activity of tissue plasminogen activator, thereby promoting fibrin hydrolysis and reinforcing its antithrombotic efficacy. Additionally, fibrinogenase may directly degrade plasminogen into small soluble fragments, which can then be decomposed and cleared from circulation, contributing to its fibrinolytic effect.9 Previous studies have indicated that fibrinogenase for injection improves neurological deficit and functional outcomes in patients with AIS, without an increased risk of haemorrhage.10–12 It also offers a broader therapeutic window, permitting administration within 72 hours after stroke onset.11 Thus, fibrinogenase may present a beneficial treatment option for patients with AIS. However, existing studies on fibrinogenase for injection have been largely retrospective, and evidence from prospective, high-quality randomised controlled trials (RCTs) remain limited.
This randomised clinical trial was designed to evaluate the efficacy and safety of fibrinogenase for injection in improving 90-day functional outcomes in patients with AIS who did not receive reperfusion therapies.
Methods
Study design
This trial was a multicentre, randomised, double-blind, placebo-controlled study conducted at 12 centres in China from 20 November 2020 to 22 July 2022. The full study protocol and statistical analysis plan are detailed in online supplemental file 1.
An independent data safety monitoring board, including clinicians and biostatisticians, monitored study conduct and data integrity. The study was conducted in accordance with the 2010 Consolidated Standards of Reporting Trials guidelines.
Study population
Patients were assessed for eligibility according to the following criteria: (1) aged 18–85 years; (2) diagnosed with AIS; (3) with an NIH Stroke Scale (NIHSS) score between 4 and 25; (4) first-ever stroke; (5) prestroke modified Rankin Scale (mRS) score ≤2; (6) able to receive study agents within 72 hours of stroke onset and (7) without IVT and MT.
The exclusion criteria included: (1) intracranial haemorrhage; (2) intracranial tumour and aneurysm; (3) those who have taken other fibrinolytic drugs or drugs that affect the formation of fibrinogen and thrombus fibrin such as snake venom preparations within 1 week; (4) patients who have taken or need oral anticoagulants with INR>1.7 or PT>15 s; (5) required dual antiplatelet therapy; (6) acute haemorrhage tendency and coagulation disorders; (7) aortic arch dissection; (8) positive skin test; (9) severe hepatic and renal insufficiency, active cavitary pulmonary tuberculosis and peptic ulcer; (10) severe disorders of consciousness; (11) pregnant or lactating. Detailed exclusion criteria are presented in online supplemental file 1.
Randomisation and blinding
The centralised randomisation procedure was performed by statisticians from Sichuan University (Chengdu, China) who were independent of the trial, with details provided in online supplemental file 1. Blocks of four were used to generate randomisation numbers. The statisticians were responsible for blinding by substituting the manufacturer’s label with a clinical trial label containing the randomisation number. Except for the randomisation number, the packaging labels for fibrinogenase for injection and placebo were identical. Drug allocation was independently conducted by trained nurses. on patient enrolment, treatment pack with the lowest number was selected from a box containing four treatment packs. All investigators and participants remained blinded to the treatment allocation.
Intervention
Eligible patients were randomised in a 1:1 ratio to receive fibrinogenase for injection or placebo. Patients were given the first dose of study drug within 72 hours after onset of symptoms based on standard treatment for AIS. Patients were randomised into the following two groups:
Intervention group: 100 units (one vial)/time/day fibrinogenase for injection were given for the first dose, and 300 units (three vials)/time/day once daily for later days, diluted in 250 mL of 0.9% saline or 5% glucose injection before intravenous drip and continuously infused for one treatment course (7 days).
Control group: placebo injection with the appearance consistent with that of fibrinogenase for injection, 1 vial/time/day for the first dose and three vials/time/day thereafter, diluted in 250 mL of 0.9% saline or 5% glucose injection before intravenous drip and continuously infused for one treatment course (7 days).
Outcomes
The primary efficacy outcome was assessed by the mRS score at 90 days after randomisation.13 Prespecified subgroup analyses were performed according to demographics (age and sex), cardiovascular risk factors (including history of smoking, hypertension, diabetes, hyperlipidaemia and coronary heart disease), baseline NIHSS score (4–5, 6–10 and >10) and time from onset to randomisation (≤24 hour, 24–48 hour, 48–72 hour).
The secondary efficacy outcomes were the proportion of functional independence (mRS score 0–2) at 30 and 90 days; NIHSS score at 8 days, 30 days and 90 days; Stroke Specific Quality of Life Scale, Three-level European Five-dimensional Questionnaire (EQ-5D-3L) score and Barthel index (at 8 days, 30 days and 90 days, respectively); recurrence events of AIS at 30 days and 90 days; incidence of neurological improvement (NIHSS score increase ≥4 points during treatment); venous thrombosis of lower extremities during treatment; changes in blood indicators (fibrinogen, D-dimer, TpP at baseline and 8 days).
The primary safety outcome was haemorrhagic events (defined by PLATelet inhibition and patient Outcomes, PLATO) during treatment.14 The secondary safety outcomes were haemorrhagic events (defined by PLATO) at 30 days and 90 days; any adverse events during treatment; death during treatment and within 90 days.
Sample size calculation
According to a previous meta-analysis by Lees et al, the proportion of AIS patients with 90-day mRS 0–1 in routine clinical care was 35%.15 We assumed that the fibrinogenase group could achieve a good prognosis of 60%, referring to a previous Chinese study of thrombolytic therapy.16 According to the WAKE-UP Study, a difference of 8% in the proportion of patients with 90-day mRS 0–1 between the two groups was considered clinically significant. With a two-sided α of 0.05 and 0.8 statistical power, the single group sample size was calculated as 97 subjects and the total sample size was 194 subjects. Allowing for a 20% loss to follow-up, the total sample size was calculated to be 240 participants.
Statistical analysis
For the efficacy analysis, data were performed in intention-to-treat (ITT) population comprising all randomised and consenting patients, and in the per-protocol population, which was defined by completion of treatment without major violation of the trial protocol. Analyses of safety outcomes were conducted in the population of patients receiving at least one dose of the study drug with available safety assessments.
Categorical variables were reported as counts with percentages and compared via the χ2 test. Continuous variables were summarised as median (IQR) and compared using the Wilcoxon test. Between-group comparisons of efficacy and safety outcomes were performed. The last observation carried forward method was applied to impute missing efficacy data in the ITT analyses. Binary outcomes were analysed using χ2 test or Fisher's exact test. ORs with 95% CI were estimated using logistic regression analysis. Adverse events were compared using the same tests, as appropriate.
No interim analyses were planned. All tests were two-sided, with p<0.05 considered significant. All statistical analyses were conducted using SAS software, V.9.4 (SAS Institute, Inc, Cary, North Carolina).
Results
Baseline characteristics
From 20 November 2020 to 22 July 2022, 235 patients with AIS were randomly enrolled. Due to the COVID-19 pandemic, the patients’ enrolment process is falling behind the original schedule of this study. In the end, some medications have exceeded the quality guarantee period. Limited by the randomisation method, the medication cannot be restored. Therefore, we stopped the trial early and had reached the primary outcome. Two patients withdrew the informed consent. Finally, 233 patients were included in the ITT population. 117 patients were assigned to receive fibrinogenase for injection, and 116 patients were assigned to receive placebo. Overall, 7 (3.0%) were enrolled inappropriately, 23 (9.9%) received prohibited concomitant medications, 4 (1.7%) died due to non-stroke causes and 2 (0.9%) were lost to follow-up at 90 days. Thus, 98 patients who received fibrinogenase for injection and 99 patients who received placebo were included in the per-protocol population (online supplemental figure S2).
Baseline characteristics were balanced between the two groups except for gender (table 1). The median age of participants was 68.0 years, and 91 (39.1%) were women. Baseline median NIHSS score was 6 (IQR 4.5–8) for patients in the fibrinogenase for injection group and 5 (IQR 4–7) in the placebo group.
Table 1. Baseline characteristics of patients.
| Fibrinogenase n=117 |
Placebo n=116 |
P value | |
|---|---|---|---|
| Age | 68.0 (57.0–75.5) | 68.0 (58.0–75.0) | 0.654 |
| Male | 62 (52.99%) | 80 (68.97%) | 0.012 |
| Smoke | 36 (30.77%) | 34 (29.31%) | 0.808 |
| Medical history | |||
| Hypertension | 60 (51.28%) | 63 (54.31%) | 0.643 |
| Diabetes | 32 (27.35%) | 25 (21.55%) | 0.303 |
| Hyperlipidaemia | 1 (0.85%) | 4 (3.45%) | 0.361 |
| Coronary heart disease | 2 (1.70%) | 6 (5.17%) | 0.275 |
| Baseline NIHSS score | 6 (4.5–8) | 5 (4-7) | 0.258 |
| Median (IQR)* | |||
| 4–5 | 58 (49.57%) | 63 (54.31%) | |
| 6–10 | 45 (38.46%) | 43 (37.07%) | |
| ˃10 | 14 (11.97%) | 10 (8.62%) | |
| Time from onset to randomisation, h (IQR) | 36.83 (24.66, 51.05) | 37.05 (24.38, 49.50) | 0.638 |
| Fibrinogen (IQR) | 3.10 (2.61–3.57) | 2.96 (2.48–3.62) | 0.262 |
| D-dimer (IQR) | 0.36 (0.25–0.58) | 0.36 (0.24–0.67) | 0.755 |
| TpP (IQR) | 7.37 (5.86–9.01) | 6.89 (5.61–9.59) | 0.323 |
| TOAST subtype, n (%) | |||
| LAA | 60 (51.28%) | 53 (45.69%) | 0.393 |
| CE | 4 (3.42%) | 8 (6.90%) | 0.230 |
| SAO | 48 (41.03%) | 49 (42.24%) | 0.851 |
| Others | 5 (4.27%) | 6 (5.17%) | 0.746 |
Data are n (%) unless specified.
Scores on the NIHSS with scores ranging from 0 to 42 and higher scores indicating greater neurological deficit.
Scores on the modified Rankin scale range from 0 to 6, with higher scores indicating greater disability.
CE, cardiogenic embolism; LAA, large artery atherosclerosis; mRS, modified Rankin Scale; NIHSS, NIH Stroke Scale; SAO, small artery occlusion; TOAST, Trial of Org 10172 in Acute Stroke Treatment; TpP, thrombus precursor protein.
Efficacy outcomes
The primary efficacy outcome among all 233 patients is shown in table 2 and figure 1. At 90 days, the mRS score was significantly lower in the fibrinogenase group (1 (0–2)) than the placebo group (2 (1–3)), with a favourable shift in mRS distribution (OR 2.38, 95% CI 1.49 to 3.85; p<0.001). Similar results were observed in the per-protocol analysis (online supplemental table S2 and figure S2).
Table 2. Efficacy outcomes.
| Fibrinogenase n=117 |
Placebo n=116 |
Treatment effect* (95% CI) |
P value | |
|---|---|---|---|---|
| Primary efficacy outcome | ||||
| mRS, 90 days median (IQR)‡† | 1.0 (0.0–2.0) | 2.0 (1.0–3.0) | 2.38 (1.49 to 3.85) | <0.001 |
| Secondary efficacy outcomes mRS (0–2 score ratio) † | ||||
| D30 | 79 (67.52%) | 78 (67.24%) | 1.01 (0.59 to 1.75) | 0.964 |
| D90 | 94 (80.34%) | 82 (70.69%) | 1.69 (0.92 to 3.11) | 0.088 |
| NIHSS median (IQR) 8 days † | 3.0 (2.0–6.0) | 4.0 (2.0–6.0) | 1.24 (0.79 to 1.94) | 0.356 |
| NIHSS median (IQR) 30 days † | 2.0 (1.0–4.0) | 2.0 (2.0–4.0) | 1.44 (0.91 to 2.28) | 0.117 |
| NIHSS median (IQR) 90 days † | 1.0 (0.0–2.0) | 2.0 (1.0–4.0) | 1.95 (1.23 to 3.10) | <0.001 |
| SS-QOL 8 days † | 174.94±40.94 | 172.30±43.87 | – | 0.635 |
| SS-QOL 30 days † | 204.0 (169.5–232.0) | 197.5 (170.5–224.3) | – | 0.454 |
| SS-QOL 90 days † | 228.0 (198.0–243.0) | 211.0 (183.0–239.8) | – | 0.097 |
| EQ-5D-3L 8 days † | 80.0 (65.0–85.0) | 75.0 (60.0–85.0) | – | 0.625 |
| EQ-5D-3L 30 † | 85.0 (72.5–90.0) | 80.0 (70.0–90.0) | – | 0.147 |
| EQ-5D-3L 90 days † | 90.0 (80.0–95.0) | 85.0 (80.0–90.0) | – | 0.005 |
| BI 8 days † | 70.0 (55.0–85.0) | 75.0 (51.25–90.0) | – | 0.470 |
| BI 30 days † | 95.0 (70.0–100.0) | 90.0 (71.3–100.0) | – | 0.872 |
| BI 90 days † | 100.0 (90.0–100.0) | 95.0 (75.0–100.0) | – | 0.017 |
| Ischaemic stroke recurrence event 30 days † | 0 | 0 | – | – |
| Ischaemic stroke recurrence event 90 days † | 1 (0.89%) | 1 (0.88%) | – | 0.994 |
| Patients with NIHSS score≥4 during treatment† | 1 (0.85%) | 3 (2.59%) | – | 0.309 |
| Thrombus of lower extremity veins§† | 0 | 1 (0.88%) | – | 0.318 |
| Changes in blood indicators† | ||||
| Fibrinogen | 3.2 (2.7–3.9) | 3.0 (2.6–3.6) | – | 0.219 |
| D-dimer | 0.4 (0.2–0.7) | 0.4 (0.2–0.8) | – | 0.546 |
| TpP | 4.2 (3.2–6.0) | 6.2 (4.9–8.2) | – | <0.001 |
Data are n (%) unless specified.
The treatment effect was reported for the primary outcome as OR (95% CI) for the ordinal shift in the distribution of scores on the modified. Thrombus of lower extremity veins and ischaemic stroke recurrence events were reported as the adjusted OR (95% CI) or as Fisher’s exact test for small numbers. The other outcomes were reported as Wilcoxon rank sum test.
One missing value for the fibrinogenase group and one missing value for the placebo group for mRS score at 30 and 90 days. Two missing values for the fibrinogenase group and one missing value for the placebo group for NIHSS score, SS-QOL, EQ-5D-3L and BI (at 8, 30, 90 days). Five missing values for the fibrinogenase group and two missing values for the placebo group for thrombus of lower extremity veins event at 7-day visit (or at discharge) and ischaemic stroke recurrence event at 30 days and 90 days.
Scores on the modified Rankin scale range from 0 to 6, with higher scores indicating greater disability.
Thrombus of lower extremity veins reported by lower extremity venous ultrasound at 7-day visit (or at discharge).
BI, Barthel Index Scale; EQ-5D-3L, Three-Level European Five-dimensional Questionnaire; mRS, modified Rankin Scale; NIHSS, NIH Stroke Scale; SS-QOL, Stroke Specific Quality of Life Scale; TpP, plasma thromboproprotein.
Figure 1. Distribution of modified Rankin Scale (mRS) scores at 90 days intention-to-treat population analysis. A score of 0 on the mRS indicates no symptoms, a score of 1 indicates no clinically significant disability, a score of 2 indicates slight disability, a score of 3 indicates moderate disability, a score of 4 indicates moderately severe disability, a score of 5 indicates severe disability and a score of 6 indicates death. Information on the primary outcome measure was missing in one patient in the fibrinogenase group and one patient in the placebo group. Missing values were imputed.
In the analyses of secondary efficacy outcomes, the median NIHSS score at 90 days was significantly lower in the fibrinogenase group (1 (0–2)) than in the placebo group (2 (1–4)) (OR 1.95, 95% CI 1.23 to 3.10; p<0.001; table 2). Fibrinogenase group had higher EQ-5D-3L scores for physical health (median score 90.0 (IQR 80.0–95.0) vs 85.0 (80.0–90.0); p=0.005) and Barthel Index Scale (median score 100.0 (IQR 90.0–100.0) vs 95.0 (75.0–100.0); p=0.017) at 90 days than placebo group. Secondary efficacy outcomes in the per-protocol analyses are presented in online supplemental table S2.
Safety outcomes
Safety outcomes are presented in table 3 and online supplemental table S3. No significant difference was observed in the incidence of haemorrhagic events during treatment (HR 3.08 (95% CI 0.32 to 30.05); p=0.333). The secondary safety endpoints had no differences between the fibrinogenase for injection group and the placebo group, including the haemorrhagic events at 30 days and 90 days, any adverse events during treatment and mortality during treatment and at 90 days.
Table 3. Safety outcomes.
| Fibrinogenase n=117 |
Placebo n=116 |
Treatment effect (95% CI) |
P value | |
|---|---|---|---|---|
| Primary safety endpoint | ||||
| Haemorrhagic events 8 days | 1 (0.85%) | 3 (2.59%) | 3.08 (0.32 to 30.05) | 0.333 |
| Secondary safety endpoints | ||||
| Haemorrhage events 30 days | 3 (2.56%) | 3 (2.59%) | – | 0.992 |
| Haemorrhage events 90 days | 3 (2.56%) | 3 (2.59%) | – | 0.992 |
| Any adverse events during treatment | 23 (19.66%) | 27 (23.28%) | 0.501 | |
| Deaths 8 days | 1 (0.85%) | 0 | – | 0.997 |
| Death events 90 days | 2 (1.71%) | 2 (1.72%) | 1.01 (0.14 to 7.28) | 0.993 |
Data are n (%) or n (%, 95% CI). Data are n (%) unless specified. The treatment effect is reported for haemorrhagic events (censored at 8 days), as an adjusted hazard ratio (95% CI). Other outcomes were reported as the adjusted HR (95% CI) or as Fisher’s exact test for small numbers. Haemorrhagic events were defined by PLATO, including intracranial haemorrhage, faecal occult blood, haematuria and large area of skin purpura. Any adverse events during treatment comprised 20 preferred terms: occult blood in stool, occult blood in urine, headache, constipation, dizziness, palpitation, rash, paroxysmal sweating, abdominal distension, bradycardia, right knee pain, hypoglycaemia, facial dermatitis, abdominal discomfort, fatigue, epigastric discomfort, acid reflux, belching, infusion reaction, pruritus, poor sleep and dry stool.
PLATO, PLATelet inhibition and patient Outcomes.
Subgroup analyses
Results of the prespecified subgroup analyses are presented in figure 2. In the subgroup analysis by sex, male patients seemed more likely to benefit from fibrinogenase for injection. Further analyses on sex-based outcomes are provided in online supplemental table S4 and S5. Additionally, no significant benefit was observed in the NIHSS >10 subgroup, and the apparent benefit was more pronounced in patients with lower baseline NIHSS (OR 4.5 for NIHSS 4–5 vs OR 3.0 for NIHSS 6–10). In the subgroup analysis by time from onset to randomisation, no significant benefit was observed in the 48–72-hour subgroup, whereas the clinical benefit was evident in those randomised within 48 hours of symptom onset (OR 4.25 for ≤24 hours vs OR 2.56 for 24–48 hours). Furthermore, patients with a history of hypertension and those without diabetes appeared to benefit from fibrinogenase for injection.
Figure 2. Prespecified subgroup analysis of the primary outcome. The forest plot displays effect variation across nine prespecified subgroups. A lower mRS score indicates less disability. CHD, coronary heart disease; NIHSS, National Institutes of Health Stroke Scale; mRS, modified Rankin Scale.
Discussion
This randomised clinical trial demonstrated that, in patients with AIS who did not receive reperfusion therapies, treatment with fibrinogenase for injection resulted in improved 90-day functional outcomes compared with placebo. This clinical benefit was particularly evident among those who were randomised within 48 hours of symptom onset and in those with mild to moderate stroke caused by large artery atherosclerosis (LAA) or small artery occlusion (SAO). Results for secondary endpoints revealed that fibrinogenase for injection was associated with improved neurological deficit and quality of life at 90 days. The occurrence of haemorrhagic events and mortality was comparable between the fibrinogenase and placebo groups.
Fibrinogenase directly acts on the TpP, a protein linked to death and ischaemic complications in acute coronary syndrome patients.17 In our study, treatment with fibrinogenase resulted in significantly lower TpP levels compared with placebo, while the D-dimer level showed no significant intergroup differences. This finding proved that fibrinogenase acts on the TpP without affecting coagulation function. It is important to note that fibrinogenase cannot dissolve the fibrin that has already been formed, and therefore cannot replace the thrombolytic effect of recombinant tissue plasminogen activator.18 The efficacy and safety of fibrinogenase for injection in AIS, as observed in our study, align with findings from previous research.11
The interpretation of our findings should take into account the predominant stroke mechanisms within our trial. The majority of enrolled participants presented with mild-to-moderate stroke, primarily attributable to LAA or SAO. Notably, LAA is also a leading mechanism for large vessel occlusion (LVO) in Asian populations.19 As vascular imaging was not performed for all participants, we were unable to perform a subgroup analysis to evaluate the efficacy of fibrinogenase specifically in patients with confirmed LVO. In subgroup analyses, the attenuated treatment effect observed in patients with NIHSS ˃10 may reflect a higher prevalence of underlying LVO in this subgroup.20 The RESCUE BT trial failed to prove the efficacy of intravenous tirofiban prior to MT in LVO stroke.21 However, the RESCUE BT2 trial proved the efficacy in patients without large or medium-sized vessel occlusion (median NIHSS score was 9).22 While our findings support the use of fibrinogenase in mild-to-moderate stroke due to LAA or SAO, its efficacy in patients with moderate-to-severe stroke potentially due to LVO remains uncertain and requires further investigation.
The time window of reperfusion therapies for patients with AIS is relatively narrow. Recent randomised trials have extended the time window of IVT using imaging-based selection. The EXTEND trial and the TRACE-III trial demonstrated improved functional outcomes in selected patients, although with an increased risk of symptomatic intracranial haemorrhage.3 5 However, the TIMELESS and ROSE-TNK trials of late-window tenecteplase did not show significant benefit.23 24 A recent meta-analysis of RCTs demonstrated that IVT was associated with improved functional outcomes but increased risk of symptomatic intracranial haemorrhage.25 Our findings suggest that fibrinogenase may provide an alternative therapeutic approach for patients with AIS ineligible for reperfusion therapies, particularly those with mild-to-moderate deficits due to LAA or SAO.
To our knowledge, this trial represents the largest randomised clinical study suggesting that fibrinogenase for injection may improve functional outcomes for patients with AIS. A strength of this trial is the placebo-controlled, double-blind study design, which reduces the potential for subjective bias from investigators and participants affecting the results. Overall, our results provide clinical evidence supporting the use of fibrinogenase for injection in selected patients with AIS, as it shows improvement in those randomised within 48 hours of symptom onset who presented with mild to moderate stroke due to LAA or SAO.
We acknowledge several limitations in this study. First, enrolment was based on baseline NIHSS scores, which ranged from 4 to 25, but the majority of included patients actually had mild to moderate strokes (median baseline NIHSS score of 6 in fibrinogenase group and 5 in placebo group), leading to a higher-than-expected functional outcomes at 90 days. Second, the generalisability of the findings to other populations requires further validation, as the trial was conducted exclusively in China. Third, the enrolled patients had a higher proportion of men and a lower proportion of cardioembolism, and thus the generalisability of the results may be limited. Fourth, vascular imaging was not performed for all participants, which limits the interpretation in patients with LVO. Additionally, this trial was designed to enrol patients without IVT or MT, and the results may not apply to patients with AIS receiving reperfusion therapies. An ongoing randomised trial of fibrinogenase for injection in patients with successful MT (ChiCTR2500102258) may shed additional light on this issue.
Conclusion
In this randomised clinical trial, treatment with fibrinogenase for injection was associated with improved 90-day functional outcomes compared with placebo in patients with AIS. This clinical benefit was particularly evident among those who were randomised within 48 hours of symptom onset and in those with mild to moderate stroke due to LAA or SAO. The findings suggest that fibrinogenase for injection may present a safe and effective therapeutic alternative for improving the prognosis of selected patients with AIS.
Supplementary material
Acknowledgements
We acknowledge Prof. Liang Du for the help of data analysis. We thank the investigators and research staff at the participating sites of the various participating emergency departments, intensive care units, stroke units and neurology departments (online supplemental file 1). We also thank the participants, their relatives and their families.
Footnotes
Funding: This study was supported by the Noncommunicable Chronic Diseases—National Science and Technology Major Project (2024ZD0527700); the National Key Research and Development Program of China (2018YFC1311400, 2018YFC1311401) and Beijing Science Sun Pharmaceutical Co. Ltd.
Provenance and peer review: Not commissioned; externally peer-reviewed.
Patient consent for publication: Not applicable.
Ethics approval: This study involves human participants and was approved by West China Hospital of Sichuan University Institutional Review Board (2019[1173]). The Institutional Review Boards at each participating centre approved the trial protocol. Participants gave informed consent to participate in the study before taking part.
Data availability free text: On publication of this manuscript, deidentified participant data, the study protocol and the statistical analysis plan will be available on request from academic institutions on receipt of a credible research proposal, approved by the corresponding author. Documents will be available in English only, for a prespecified time (typically 12 months) on a password-protected portal.
Data availability statement
Data are available upon reasonable request.
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Data Availability Statement
Data are available upon reasonable request.