BACKGROUND:Bleeding episodes in hemophiliacs with inhibitors are difficult to control. STSP-0601, a specific factor X (FX) activator purified from the venom of Daboia russelii siamensis, has been developed.
OBJECTIVES:To investigate the efficacy and safety of STSP-0601 in preclinical and clinical studies.
METHODS:In vitro and in vivo preclinical studies were performed. A phase 1, first-in-human, multicenter, and open-label trial was conducted. The clinical study was divided into Parts A and B. Hemophiliacs with inhibitors were eligible for this study. Patients received a single intravenous injection of STSP-0601 (0.01 U/kg, 0.04 U/kg, 0.08 U/kg, 0.16 U/kg, 0.32 U/kg, or 0.48 U/kg) in Part A or a maximum of six 4-hourly injections (0.16 U/kg) in Part B. The primary endpoint for each part was the number of adverse events (AEs) from baseline to 168 h after administration. This study was registered at ClinicalTrials.gov (NCT-04747964, and NCT-05027230).
RESULTS:Preclinical studies showed that STSP-0601 could specifically activate FX in a dose-dependent manner. In the clinical study, 16 patients in Part A and seven in Part B were enrolled. Eight (22.2%) AEs in Part A and 18 (75.0%) AEs in Part B were reported to be related to STSP-0601. Neither severe AEs nor dose-limiting toxicity events were reported. There was no thromboembolic event. The anti-drug antibody of STSP-0601 was not detected.
CONCLUSIONS:Preclinical and clinical studies showed that STSP-0601 had good ability to activate FX and had a good safety profile. STSP-0601 could be used as a hemostatic treatment in hemophiliacs with inhibitors.