OC 42.5 - Hemorrhagic risk of Caplacizumab in the treatment of Thrombotic thrombocytopenic purpura A pharmacovigilance study from 2020-2022 FAERS Database.

Background: The FDA approved Caplacizumab in 2019 to treat thrombotic thrombocytopenic purpura (TTP), which decreases major thromboembolic complications (1,2). It works by inhibiting the interaction between von Willebrand factor multimers and platelets, which causes thrombosis in TTP. However, one of the known side effects of this medication is an increased risk of bleeding. This study aims to evaluate the prevalence and severity of this complication in patients taking caplacizumab.

Aims: Identify the risk of bleeding in patients using caplacizumab.

Methods: We conducted a retrospective analysis of reported cases of TTP patients treated with caplacizumab over the past three years using data from the FDA's Adverse Event Reporting System (FAERS) database. Patients aged 18 or older were included, and cases were classified using the Medical Dictionary for Regulatory Activities (MedDRA) terminology.

Results: Hemorrhagic complications occurred in 24.95% (126) of 505 TTP patients taking caplacizumab. Most patients experiencing hemorrhage were female (68.25%), with a median age of 48. The most common type of hemorrhage was epistaxis (33.33%), followed by gastrointestinal bleeding (26.19%). Of the patients with hemorrhage, 75 (59.52%) had serious complications, 10 deaths were reported, 6 cases were intracranial hemorrhage, and 3 were gastrointestinal. Intracranial hemorrhage was particularly severe, with 6 deaths out of 8 reported cases.

Conclusion(s): Our study shows that bleeding is a common complication of Caplacizumab, which decreases the VWF levels and increases bleeding risk. The current practice is to check VWF levels once after the first day of therapy. However, our findings suggest the potential benefit of more frequent monitoring of VWF levels and identifying a certain cutoff level. If the level falls below this cutoff, prompt modification of the caplacizumab dosing may be necessary to prevent the bleeding. Further research is needed to determine the optimal frequency and cutoff level for VWF monitoring and to identify patients most at risk.