Grifols' fibrinogen concentrate BT524 has successfully met its primary endpoint in a Phase III clinical trial, demonstrating non-inferiority to standard of care treatments for managing bleeding in patients with acquired fibrinogen deficiency (AFD) undergoing major surgery. The positive results, published in eClinicalMedicine, a peer-reviewed journal from The Lancet Discovery Science Suite, mark a significant advancement in surgical hemorrhage management.
Trial Results Show Reduced Blood Loss
The AdFIrst (Adjusted Fibrinogen Replacement Strategy) trial demonstrated that BT524 was non-inferior to standard of care with cryoprecipitate or fresh frozen plasma (FFP) in reducing clinically relevant intraoperative bleeding. The adjusted mean intraoperative blood loss was 1,381 mL (95% confidence interval 1187–1574) in the BT524 group compared to 1,660 mL (95% CI 1461–1860) in the FFP/cryoprecipitate group, resulting in a 279 mL reduction in blood loss.
Beyond meeting the primary endpoint, BT524 demonstrated a positive safety profile with a statistically significant lower incidence of thromboembolic events compared to standard treatments.
Clinical Significance for Surgical Patients
Fibrinogen, a plasma protein produced in the liver, plays a crucial role in stopping blood loss and wound healing. AFD is typically associated with major uncontrolled bleeding during surgical procedures, trauma, or postpartum hemorrhage. When fibrinogen levels are insufficient to arrest bleeding, patients are commonly treated with fibrinogen sources such as cryoprecipitate.
"The trial results, now featured in this prestigious clinical medicine journal, support the potential of BT524 to be considered for patients with clinically relevant uncontrolled bleeding," said Dr. Jörg Schüttrumpf, Grifols Chief Scientific Innovation Officer.
Study Design and Methodology
The AdFIrst trial was a prospective, active-controlled, multicenter Phase III non-inferiority study investigating the efficacy and safety of BT524 in patients with acquired fibrinogen deficiency. Patients experiencing high blood loss during planned spinal or abdominal surgery were randomized 1:1 to treatment with BT524 or cryoprecipitate/FFP.
The primary endpoint measured intraoperative blood loss from the time of treatment decision until surgery completion, with a non-inferiority margin of 150 mL assessed in the per-protocol analysis set. Safety was evaluated in all patients who received at least one dose of the trial drug.
Regulatory Timeline and Market Access
BT524 is on track for launch in Europe later this year, with U.S. approval pending FDA review expected in early 2026. The fibrinogen concentrate was developed by Biotest, a Grifols Group company, representing the culmination of collaborative research efforts.
Niels Rahe-Meyer, M.D., from Hannover Medical School's Department of Anesthesiology and Intensive Care Medicine and main trial coordinator, noted, "These data could represent a breakthrough in our understanding of hemorrhage management with fibrinogen."
Treatment Advantages
Unlike FFP and cryoprecipitate alternatives that contain variable amounts of fibrinogen and require thawing prior to treatment, the defined amount of fibrinogen in BT524 allows for tailored, patient-specific therapy. This standardization could improve treatment outcomes and reduce preparation time in critical surgical situations.
Conference Presentations
The study results were presented through three abstracts at the International Society on Thrombosis and Haemostasis (ISTH) 2025 Congress in Washington, D.C., covering post-hoc analysis of the Phase III trial, early intraoperative use in abdominal surgery, and efficacy and safety during major spinal surgery.
Previously, AdFIrst data have been presented at multiple medical conferences including the International Symposium on Intensive Care & Emergency Medicine, Network for the Advancement of Patient Blood Management, Haemostasis and Thrombosis, and the European Society of Anaesthesiology and Intensive Care.
