Staidson's Bojianing: World's First Factor X Activator Breaks Through Hemophilia's Most Intractable Inhibitor Dilemma

The development of neutralizing inhibitors against clotting factors represents the most severe and difficult-to-manage immune-related complication in hemophilia replacement therapy. For patients with high-titer inhibitors (>5 Bethesda Units), conventional Factor VIII/Factor IX infusions become completely ineffective, leading to recurrent spontaneous bleeding episodes, progressive joint disability, and significantly elevated risk of life-threatening hemorrhage and death.

According to the World Federation of Hemophilia's "Inhibitors to Clotting Factors" guideline, patients with high-titer inhibitors (>5BU) show no response to standard clotting factor infusions, experience frequent spontaneous bleeding episodes with rapidly progressive arthropathy, and face elevated risks of fatal hemorrhage and mortality. Inhibitors remain among the most serious complications in hemophilia treatment.

For years, hemophilia patients with inhibitors have confronted multiple unmet medical needs: limited treatment options, a global void in therapeutic drugs for this indication, incomplete coverage across patient subtypes, and an overwhelming economic burden.

Pomithrombin Alfa for Injection (trade name: Bojianing®), developed by Jiangsu Beijietai Bio—a subsidiary of Staidson (Beijing) Biopharmaceuticals Co., Ltd.—represents a breakthrough in this space. As the world's first Factor X (FX) activator and a National Class 1 biological innovative drug, Bojianing® received conditional approval from China's National Medical Products Administration (NMPA) on June 4, 2026, specifically for the treatment of bleeding in adult patients with congenital hemophilia A or B with inhibitor titers exceeding 5BU.

High-Titer Inhibitors in Hemophilia: The Most Intractable Clinical Challenge

Inhibitors are IgG-type neutralizing antibodies produced by the body following administration of exogenous Factor VIII or Factor IX, constituting a core refractory complication of hemophilia. Epidemiological data reveal that the incidence of inhibitors ranges from 20% to 30% in patients with severe hemophilia A, while hemophilia B patients exhibit a comparatively lower incidence of 1.5% to 3%.

Inhibitors are classified by Bethesda titer, with levels exceeding 5BU defined as high-titer inhibitors. High-titer inhibitors account for approximately 75% of all inhibitor cases, and in these patients, conventional clotting factor replacement therapy may fail entirely.

The Core Clinical Burden for High-Titer Inhibitor Patients

According to the "Chinese Guidelines for Diagnosis and Treatment of Hemophilia with Inhibitors (2023 Edition)," patients with high-titer inhibitors (Bethesda titer >5BU) may experience complete failure of conventional clotting factor replacement therapy, representing the most difficult-to-manage population with the poorest prognosis in hemophilia clinical management.

The core diagnostic and therapeutic challenges can be categorized as follows:

1. Uncontrollable Bleeding with Significantly Elevated Disability and Mortality Risk: Per the 2023 Chinese Guidelines, high-titer inhibitor patients show poor or no response to conventional clotting factor therapy, rendering bleeding uncontrollable. Life-threatening hemorrhage constitutes the primary cause of death in this patient population.

2. Limited Options for Inhibitor Eradication with Modest Overall Treatment Benefits: Immune tolerance induction (ITI) therapy requires patients to undergo frequent venipuncture and receive large quantities of clotting factors. Both treatment costs and patient compliance affect ITI success rates. Moreover, ITI success rates for hemophilia B patients with inhibitor positivity stand at merely 30%, accompanied by risks of allergic reactions and irreversible renal impairment. Consequently, ITI implementation in hemophilia B inhibitor-positive patients warrants caution.

3. Inherent Limitations of Existing Clinical Therapies Failing to Address All Clinical Scenarios: Historical intervention approaches suffer from restricted patient populations, elevated safety risks, and incomplete coverage across patient subtypes. These therapies prove particularly inadequate for hemophilia B inhibitor populations, with breakthrough bleeding emergency management persistently displaying notable shortcomings.

4. Global Innovation Filling Long-Standing Drug Voids with Insufficient Primary Care Access: International options including recombinant Factor VIIa (rFVIIa) and bispecific prophylactic antibodies can address bleeding in hemophilia patients with high-titer inhibitors. However, both domestically and internationally, no comprehensive domestic innovative treatment system covering both hemophilia A and B inhibitor patients exists. Current mainstream clinical approaches in China rely on imported medications, driving treatment costs persistently upward and limiting patient access to therapies. Compounding this issue, primary medical institutions lack adequate treatment infrastructure, preventing standardized and routine management of acute bleeding episodes and creating substantial clinical demand gaps.

Bojianing®'s Globally First-in-Class Mechanism: Completely Bypassing Inhibitor Interference

The intrinsic coagulation pathway relies on the Factor VIII-Factor IX complex to efficiently activate Factor X, generating a coagulation amplification effect. In patients with high-titer inhibitors, anti-Factor VIII and anti-Factor IX neutralizing antibodies completely block this intrinsic coagulation amplification pathway. Traditional bypassing agents can only indirectly and passively initiate the coagulation process, unable to reconstruct the unique coagulation amplification efficacy of the intrinsic pathway. Constrained by their mechanisms of action, these agents universally exhibit relatively weak hemostatic effects, significant efficacy variability, and recurrent bleeding.

Bojianing®, independently developed by Staidson, represents the world's first FX-specific activator. It directly and potently activates Factor X, reconstructing the complete coagulation amplification response without any dependence on the Factor VIII/Factor IX pathway. From a mechanistic standpoint, Bojianing® overcomes the inherent deficiencies of traditional bypassing agents, demonstrating stable hemostasis and low bleeding recurrence rates. Importantly, it demonstrates equal applicability for both hemophilia A and B patients with high-titer inhibitors.

Bojianing®'s hemostatic mechanism operates entirely independently of Factor VIII and Factor IX molecules. Consequently, endogenous inhibitors (anti-Factor VIII and anti-Factor IX neutralizing antibodies) cannot exert inhibitory effects against it.

This translates into several critical advantages: high-titer inhibitor hemophilia A patients can be treated; high-titer inhibitor hemophilia B patients can be treated; efficacy persists even after conventional factor infusions fail; and the drug fills the void of dedicated domestic emergency therapies for hemophilia B inhibitors.

Bojianing® Multicenter Clinical Evidence: Dual Advantages in Efficacy and Safety

The pivotal clinical study (Phase IIb) enrolled adult hemophilia A/B patients with high-titer inhibitors. The unified dosing regimen was 0.10U/kg, repeatable every 4 hours until hemostasis was achieved. The primary endpoint—12-hour effective hemostasis rate—reached 81.94%, significantly exceeding the pre-set single-arm target value of 55% (P<0.0001), demonstrating statistical significance.

Stratified Efficacy

For first bleeding episodes, the 12-hour effective hemostasis rate reached 88.00%. For target joint bleeding, the 12-hour effective hemostasis rate stood at 86.96%. Notably, effective hemostasis rates showed no difference between hemophilia A and B patients, indicating that Bojianing® delivers significant clinical value across both hemophilia types with high-titer inhibitors.

Dosing Convenience

In 77.12% of bleeding events, only one to two intravenous administrations were required to achieve stable hemostasis. The average number of administrations was merely 1.9±0.7. Compared with rFVIIa, Bojianing® significantly reduces the number of administrations, minimizing the burden of repeated intravenous injections and improving treatment compliance.

High-Dose Data

Phase Ib/II data demonstrated that the 0.16U/kg high-dose group achieved a hemostasis rate of 96.48%. This provides higher dosing options for severe bleeding, trauma, or post-surgical hemorrhage scenarios.

Complete Clinical Trial Safety Evidence

Based on pooled safety data from Phase I, Ib/II, and IIb studies, Bojianing® demonstrated an overall favorable safety profile. No Grade 3 or higher drug-related adverse events occurred. No drug-related serious adverse events (SAEs) were reported. Approximately 36% of subjects experienced Grade 1 mild adverse reactions, most of which required no intervention and resolved spontaneously. No thromboembolic events occurred across all clinical trials.

Immunogenicity risk proved extremely low. Follow-up results across all clinical trial phases showed that no anti-drug antibodies (ADA) were detected in any subjects. No drug-related immune reactions, no neutralizing antibody production, no allergy or immune-related adverse events occurred, and hemostatic efficacy remained unaffected.

These findings support long-term, repeated use for bleeding treatment, indicate low propensity for developing drug-neutralizing antibodies, and demonstrate long-term management value for patients with recurrent bleeding episodes.

Strategic Significance and Future Outlook

From a clinical perspective, Bojianing® effectively complements the inhibitor bleeding treatment framework recommended in the "Chinese Guidelines for Diagnosis and Treatment of Hemophilia with Inhibitors (2023 Edition)," addressing the clinical shortcomings of traditional therapies. From an industrial standpoint, the drug achieves a globally innovative breakthrough in acute bleeding treatment for hemophilia patients with high-titer inhibitors, breaking the monopoly of imported medications.

Leveraging long-term indication expansion and systematic collaborative deployment within its pipeline, Bojianing® possesses irreplaceable clinical application value and long-term global industrialization prospects. The drug holds potential to substantially improve treatment outcomes and quality of life for hemophilia patients with inhibitors worldwide.

References: Thrombosis and Hemostasis Group, Chinese Society of Hematology; Chinese Hemophilia Collaboration Group. Chinese Guidelines for Diagnosis and Treatment of Hemophilia with Inhibitors (2023 Edition). Chinese Journal of Hematology, 2023, 44(11):881-892. Chinese Guidelines for Hemophilia Treatment (2020 Edition). Chinese Journal of Hematology, 2020, 41.