What happened
Milvexian shows no benefit over placebo for major cardiovascular events after recent ACS.
Multiple clinicians converge on the same conclusion: milvexian was safe but did not reduce ischemic events after ACS, meaning factor XIa inhibition at this dose adds no benefit on top of contemporary antiplatelet therapy.
Experts read LIBREXIA ACS as a clear null result for factor XIa inhibition after ACS, with milvexian safe but ineffective at this dose, leaving the field unsure whether the target, the dose, or the population was wrong.
The reaction to LIBREXIA ACS is uniformly negative on efficacy: clinicians agree milvexian added nothing to standard antiplatelet therapy after ACS and the trial was stopped for futility. Most note the clean safety profile but see little consolation in it. The live question is whether factor XIa inhibition can still succeed in other settings such as atrial fibrillation or stroke prevention, where higher doses and different patient populations are being tested.
It remains open whether factor XIa inhibition will prove effective in other thrombotic settings.
The ongoing milvexian trials in atrial fibrillation and secondary stroke prevention use a higher dose (100 mg twice daily) in different populations, and experts and the sponsor have flagged these as distinct from the ACS program.
Whether the failure reflects the wrong dose, the wrong population, or a true limitation of the FXIa target in arterial thrombosis is unresolved.
“While no effect on efficacy was shown, the absence of an observed increase in intracranial or fatal bleeding is reassuring given that two further trials are ongoing: LIBREXIA AF for patients with atrial fibrillation and LIBREXIA Stroke for secondary stroke prevention.”
From published coverage, not an answer posted here.
Despite high residual risk after ACS, adding a factor XIa inhibitor did not help
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The Factor XIa hypothesis did not deliver efficacy in ACS
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Milvexian did not reduce MACE but maintained a favorable safety profile
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Neutral result with no significant reduction in ischemic events
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Trial stopped early for futility with no bleeding signal
X post ↗Robert A. Harrington
ContextDean, Weill Cornell Medicine, Cornell UniversityFXIa inhibition remains promising beyond ACS despite this failure
Original post ↗
Milvexian was safe but did not reduce events and was stopped for futility
X post ↗Matt Phipps
ContextBiotechnology equity research head, William BlairAF trial uses a fourfold higher dose and may have less read-through from this setback
Original post ↗
Shared the LIBREXIA ACS results presentation as a principal investigator alongside senior trial leaders.
X post ↗ESC Council on Stroke Chairperson
@escstrokechair“In LIBREXIA-ACS RCT Approx 14k pts Stopped earlier for futility Milvexian (25mg bid) did not reduce MACE after ACS on top of antiplatelet care”
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“LIBREXIA-ACS: the factor XIa hypothesis falls short after ACS. Milvexian 25 mg BID added to antiplatelet therapy did not reduce CV death, MI or ischaemic stroke (HR 1.05; 95% CI 0.91–1.21), but did not increase BARC 3c/5 bleeding. The unmet need remains.”
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Why the trial, key points, tables, limitations, PICO, abstract, media & sources
Why the trial?
Adding an anticoagulant to antiplatelet therapy after acute coronary syndrome reduces ischaemic events but has been limited by bleeding. Factor XIa inhibition promises antithrombotic protection with less bleeding, and LIBREXIA ACS asked whether milvexian delivers that benefit after a recent ACS.
Does milvexian reduce the risk of cardiovascular death, myocardial infarction, or ischemic stroke in patients with a recent acute coronary syndrome event?
| Outcome | Milvexian | Placebo |
|---|---|---|
| CV death, MI, or ischemic stroke | 384 (5.4%) | 365 (5.1%) |
| HR 1.05 (95% CI 0.91-1.21); P=0.50 - trial stopped for futility at interim | ||
Safety
BARC 3c or 5 bleeding (intracranial/fatal) 23/7094 (0.3%) vs 22/7100 (0.3%); P=0.88.
Statistical certainty
terminated for futility at a planned interim based on 556 adjudicated events.
Design limitations
median follow-up of 12.2 months is relatively short, and only one dose (25 mg twice daily) was evaluated.
Does milvexian reduce the risk of cardiovascular death, myocardial infarction, or ischemic stroke in patients with a recent acute coronary syndrome event?
Hazard Ratio: 1.05 (95% CI 0.91–1.21)
Absolute Event Rate: 5.4% vs 5.1%
p-value: p=0.50
In patients with recent acute coronary syndrome, adding the factor XIa inhibitor milvexian to standard antiplatelet therapy did not reduce ischemic events, leading to early termination for futility.
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Expert reaction
NEJM · ESC Congress 2026
3 experts quoted, 2 with a clear stance so far. We show the split once 3 have one.
Expert labels are toward LIBREXIA ACS's result, from named public quotes (n=2). As of Aug 29, 2026.
Experts read LIBREXIA ACS as a clear null result for factor XIa inhibition after ACS, with milvexian safe but ineffective at this dose, leaving the field unsure whether the target, the dose, or the population was wrong.
The reaction to LIBREXIA ACS is uniformly negative on efficacy: clinicians agree milvexian added nothing to standard antiplatelet therapy after ACS and the trial was stopped for futility. Most note the clean safety profile but see little consolation in it. The live question is whether factor XIa inhibition can still succeed in other settings such as atrial fibrillation or stroke prevention, where higher doses and different patient populations are being tested.
Multiple clinicians converge on the same conclusion: milvexian was safe but did not reduce ischemic events after ACS, meaning factor XIa inhibition at this dose adds no benefit on top of contemporary antiplatelet therapy.
3 takes classified by contention axis so far — the map appears as more land.
It remains open whether factor XIa inhibition will prove effective in other thrombotic settings. The ongoing milvexian trials in atrial fibrillation and secondary stroke prevention use a higher dose (100 mg twice daily) in different populations, and experts and the sponsor have flagged these as distinct from the ACS program. Whether the failure reflects the wrong dose, the wrong population, or a true limitation of the FXIa target in arterial thrombosis is unresolved.
““Why is this important in terms of safety? Because milvexian is currently being evaluated in two other large trials: one in atrial fibrillation and one in secondary stroke prevention.””
Damluji emphasized that patients remain at high risk for recurrent ischemic events after ACS despite dual antiplatelet therapy, high-intensity statins, and current-generation stents, and that LIBREXIA ACS tested whether adding an oral factor XIa inhibitor to that regimen could close the gap. He highlighted implications for both clinical practice and the factor XIa inhibitor market.
Pishoy Gouda framed the trial as testing whether FXIa inhibition could add anti-thrombotic efficacy without extra bleeding after ACS, then reported the clear negative: milvexian did not reduce CV death, MI, or ischemic stroke (HR 1.05, p=0.50). He concluded the Factor XIa hypothesis did not deliver here.
Milvexian adds no ischemic benefit after ACS; safety supports continued evaluation in ongoing atrial fibrillation and stroke prevention trials.
BackgroundPatients are at increased risk for recurrent ischemic events after an acute coronary syndrome event. Milvexian, an oral factor XIa inhibitor, may reduce the risk of major adverse clinical events with minimal bleeding risk. MethodsIn this phase 3, randomized, placebo-controlled trial, we evaluated the efficacy and safety of milvexian when added to standard antiplatelet therapy within 7 days after an acute coronary syndrome event. Patients were assigned in a 1:1 ratio to receive oral milvexian (25 mg twice daily) or matched placebo. The primary efficacy outcome was a composite of cardiovascular death, myocardial infarction, or ischemic stroke as evaluated in a time-to-event analysis. The principal safety outcome was Bleeding Academic Research Consortium (BARC) type 3c or 5 bleeding (intracranial or intraocular bleeding that compromises vision or fatal bleeding). ResultsAfter a planned interim analysis that was based on 556 adjudicated efficacy end points, the trial was terminated for futility. A total of 14,194 patients had been enrolled, with 7094 assigned to receive milvexian and 7100 to receive placebo. After a median follow-up of 12.2 months, a primary efficacy outcome event had occurred in 384 patients (5.4%) in the milvexian group and in 365 patients (5.1%) in the placebo group (hazard ratio, 1.05; 95% confidence interval, 0.91 to 1.21; P=0.50). BARC type 3c or 5 bleeding occurred in 23 patients (0.3%) in the milvexian group and in 22 patients (0.3%) in the placebo group (P=0.88). ConclusionsAmong patients with a recent acute coronary syndrome event, milvexian did not decrease the risk of cardiovascular death, myocardial infarction, or ischemic stroke but did not increase the risk of intracranial or fatal bleeding, as compared with placebo. (Funded by Janssen Research and Development and Bristol Myers Squibb; LIBREXIA ACS ClinicalTrials.gov number, NCT05754957.)
NEJM · ESC 2026 · RCT. Adding milvexian to antiplatelet therapy after ACS gives no ischemic benefit. LIBREXIA ACS: Milvexian with Antiplatelet Therapy after Acute Coronary Syndrome Event 14,194 patients: Enrolled within 7 days of an ACS event. Both added to antiplatelet therapy: Milvexian 25 mg twice daily vs Matched placebo. CV death, MI, or ischemic stroke: Milvexian 5.4% vs Placebo 5.1%. HR 1.05 (95% CI 0.91–1.21). No reduction; trial stopped early for futility. 0.3% in both arms: BARC 3c or 5 bleeding matched placebo. Bottom line: Milvexian adds no ischemic benefit after ACS; safety supports ongoing trials.
Journal, society, and media accounts. Useful signal, not independent expert judgment.
Gibson et al. (2026) conducted an RCT in Acute coronary syndrome (n=14,194). Milvexian vs. Placebo was evaluated on Composite of cardiovascular death, myocardial infarction, or ischemic stroke (HR 1.05, 95% CI 0.91-1.21, p=0.50). Milvexian added to standard antiplatelet therapy did not decrease the risk of cardiovascular death, myocardial infarction, or ischemic stroke compared with placebo (HR 1.05; 95% CI 0.91-1.21; P=0.50).
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