New Hemophilia Drug Approved in China: Bemiltenase Alfa Becomes World’s First Factor X Activator

On June 4, 2026, the NMPA officially announced that injectable Bemiltenase alfa (STSP-0601), a Class 1 innovative biologic developed by BioJeTay, a subsidiary of Shutaishen Pharmaceutical Group, received conditional approval in China.

The drug is indicated for the treatment of bleeding episodes in adult patients with congenital hemophilia A or B who have factor VIII or factor IX inhibitors >5 BU.

✨ This new hemophilia drug approved in China marks an important transition in hemophilia treatment — from the traditional coagulation factor replacement era toward a new era of coagulation pathway activation.

As a China-based pharmaceutical wholesaler focused on innovative medicines and cross-border drug access, DengYueMed continues to monitor major breakthroughs in rare disease therapies developed by Chinese biotech companies.

Hemophilia Treatment Challenges: Unmet Needs in Inhibitor Patients

Hemophilia is an X-linked inherited bleeding disorder mainly classified into hemophilia A (FVIII deficiency) and hemophilia B (FIX deficiency).

Although multiple therapies are currently available, significant unmet clinical needs remain, particularly among inhibitor-positive patients.

The major limitations of current treatment strategies include: 🔽

• High dependence on factor replacement therapy: Patients require long-term repeated infusions, while the development of inhibitors can significantly reduce or completely eliminate treatment efficacy.
• Limited stability of bypassing agents: Therapies such as rFVIIa and aPCC may show variable responses between patients, leading to inconsistent hemostatic control.
• Emerging therapies remain under development: Non-factor therapies and gene therapies show strong potential but are still limited by patient eligibility, long-term safety, and accessibility.

As a result, patients with high inhibitor titers (>5 BU) continue to face major challenges in bleeding control and treatment selection.

Against this background, new hemostatic mechanisms have become a major focus of hemophilia drug development.

Bemiltenase Alfa (STSP-0601): The World’s First Factor X Activation Mechanism

Bemiltenase alfa (STSP-0601) is a Class 1 therapeutic biologic whose active component is a coagulation factor X activator purified from the venom of Russell’s viper.

This new hemophilia drug approved in China represents the world’s first coagulation factor X activator developed for hemophilia treatment.

1. Core Mechanism of Action (Downstream Coagulation Activation)

Its hemostatic activity works through downstream activation of the coagulation cascade:

• Direct activation of coagulation factor X (FX)
• Promotion of FX conversion into FXa
• Initiation of thrombin generation and terminal clot formation

2. Key Mechanistic Advantages

Compared with traditional therapies, this mechanism provides several important advantages:

• Independent of FVIII or FIX pathways
• Able to bypass inhibitor interference
• Directly targets the common coagulation pathway

These features position Bemiltenase alfa as a major mechanistic upgrade within the bypassing therapy landscape.

Key Clinical Results: Rapid Onset and High Hemostatic Efficacy

According to the multicenter Phase IIb clinical study released in January 2025, Bemiltenase alfa demonstrated significant efficacy and favorable safety in hemophilia patients with inhibitors.

👉 This clinical data further strengthened interest in this new hemophilia drug approved in China.

1. Strong Efficacy Outcomes

• 12-hour effective hemostasis rate: 81.94%
• 12-hour hemostasis rate during first bleeding visits: 88.00%
• Effective hemostasis rate in target joint bleeding: 86.96%
• Average dosing frequency: 1.9 ± 0.7 administrations
• 77.12% of bleeding episodes controlled with only 1–2 doses

The results showed effective bleeding control in both hemophilia A and hemophilia B patients, with relatively rapid onset of action.

2. Favorable Safety Profile

• 36.00% of subjects reported treatment-related adverse events
• Most adverse events were Grade 1 mild reactions
• No Grade 3 or higher adverse events reported
• No serious adverse events or thromboembolic events observed

Overall, the benefit-risk profile of Bemiltenase alfa was considered favorable for this indication.

Current Hemophilia Treatment Landscape: Toward Multi-Mechanism Therapy

The current hemophilia treatment landscape is evolving toward a multi-mechanism therapeutic system, mainly consisting of four major approaches.

1️⃣ Coagulation Factor Replacement Therapy

Replacement of factor VIII (FVIII) or factor IX (FIX) remains the foundation of hemophilia treatment.

However, this approach still faces limitations including repeated infusion dependence and loss of efficacy after inhibitor development.

2️⃣ Bypassing Therapies

Bypassing agents are mainly used in inhibitor-positive patients by bypassing defective coagulation pathways.

Common agents include rFVIIa and aPCC, although treatment responses may vary considerably between individuals.

3️⃣ Non-Factor Therapy and Gene Therapy

Non-factor therapies improve bleeding control through coagulation mimicry mechanisms and have already entered routine clinical use in selected patients.

Gene therapy aims to restore FVIII or FIX expression through AAV vectors and represents a potential long-term curative strategy, although continued optimization and validation are still ongoing.

4️⃣ Downstream Coagulation Activation Strategy (Bemiltenase Alfa)

Beyond the traditional treatment framework, therapeutic development is now expanding toward downstream coagulation activation strategies.

As a new hemophilia drug approved in China, Bemiltenase alfa directly activates coagulation factor X (FX), initiating hemostatic reactions further downstream in the coagulation cascade.

Its major characteristics include:

• Independence from FVIII or FIX pathways
• Activity even in the presence of inhibitors
• Expansion of current therapeutic mechanism boundaries

👉 This strategy may therefore represent an important mechanistic addition to the evolving hemophilia treatment landscape.

Expanded Development Potential of Bemiltenase Alfa

Beyond its approved indication, Bemiltenase alfa is also being investigated for:

• On-demand treatment of hemophilia A/B patients without inhibitors (Phase II completed)
• Additional bleeding-related indications

Meanwhile, Shutaishen Pharmaceutical Group continues to expand innovative pipelines across infectious diseases, respiratory and critical care disorders, autoimmune diseases, and neurological diseases, demonstrating strong long-term R&D capabilities.

As global interest grows around this new hemophilia drug approved in China, Bemiltenase alfa may become an important reference point for next-generation bypassing therapy development.

Conclusion: China Enters a New Era of Hemophilia Innovation

The approval of Bemiltenase alfa (STSP-0601) not only represents a global first in coagulation mechanism innovation, but also provides a new therapeutic option for hemophilia patients with high inhibitor titers.

As hemophilia treatment evolves from factor replacement toward mechanism-driven innovation, future treatment strategies are expected to become increasingly diversified and individualized.

This new hemophilia drug approved in China also highlights the growing global role of Chinese biopharmaceutical innovation in rare disease treatment.

DengYueMed will continue tracking innovative therapies for hemophilia and other rare diseases, supporting global patients and healthcare institutions with access to emerging medicines and clinical information.

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