CSPC Pharmaceutical Group Achieves Breakthrough in Rare Cancer Treatment: Phase Ib/III Study of Albumin-Bound Sirolimus (HB1901) Meets Primary Endpoint

Hong Kong, 20 April 2026 — CSPC Pharmaceutical Group Limited (HKEX: 1093) announced a significant clinical milestone that is likely to draw strong investor attention and could have a material impact on the company’s valuation. The company’s independently developed Sirolimus for Injection (Albumin-bound), designated as HB1901, has successfully met its pre-specified primary efficacy endpoint in a Phase Ib/III clinical trial for advanced malignant perivascular epithelioid cell tumour (PEComa), a rare and aggressive cancer with no established standard treatment in China.

Key Highlights

• Breakthrough in Rare Cancer Therapy: HB1901 demonstrated statistically significant efficacy and clear clinical benefit in the pivotal Phase III trial, outperforming existing treatment options for advanced malignant PEComa.
• First of Its Kind in China: If approved, HB1901 is expected to become the first standard treatment regimen for advanced malignant PEComa in the Chinese market, addressing a substantial and urgent unmet medical need.
• Potential Market Impact: Given the absence of recognized therapies for this rare tumour, the approval and commercialization of HB1901 could position CSPC as a leader in the treatment of rare and refractory tumours, potentially expanding its oncology portfolio and revenue streams.

Details of the Clinical Study

• The Phase Ib/III clinical study (Protocol No.: HB1901-004) was designed to assess the safety and efficacy of HB1901 in patients with advanced malignant PEComa. The pivotal Phase III study involved a head-to-head comparison of HB1901 versus the investigator’s choice of therapy, confirming HB1901’s overall superiority in anti-tumour efficacy, clinical benefit, and safety/tolerability.
• The study’s success means HB1901 could become the first standard of care for a condition where approximately 50% of patients are diagnosed at an advanced stage, often with metastasis and poor prognosis.

About the Disease: Malignant PEComa

• Malignant PEComa is a rare mesenchymal tumour marked by aggressive behaviour and distinctive histological features, with high rates of recurrence and metastasis.
• There are currently no recognized standard therapies in China for patients whose tumours cannot be completely resected or who experience recurrence and distant metastasis, making this a high unmet medical need.

About HB1901: A Novel Drug Formulation

• Innovative Technology: HB1901 is an albumin-bound nanoparticle suspension of sirolimus, an mTOR inhibitor with known poor water solubility and limited oral bioavailability.
• This new injectable formulation encapsulates sirolimus in human serum albumin, enabling intravenous delivery for the first time in China—overcoming the limitations of traditional oral formulations and expanding its application in oncology.
• Compared to current oral mTOR inhibitors, HB1901 is expected to offer improved bioavailability and reduced gastrointestinal toxicity.
• HB1901 is classified as a Class 2.2 new drug under Chinese regulations, as it features a known active ingredient in a new dosage form or delivery system.

Regulatory and Development Milestones

• In February 2025, HB1901 was granted Breakthrough Therapy Designation by the National Medical Products Administration (NMPA), signifying its potential to address critical unmet needs and expedite its review process.
• Multiple ongoing clinical trials are investigating HB1901 in combination with other agents across various tumour types, indicating broader potential applications and further commercial opportunities.

Implications for Shareholders

• Price-Sensitive Information: The successful clinical results and potential to become the first standard treatment for advanced malignant PEComa in China represent highly price-sensitive developments.
• Market Leadership Potential: CSPC stands to secure a unique position in the rare oncology market, with the possibility of significant first-mover advantage and high barriers to entry for competitors.
• Regulatory Progress: The Breakthrough Therapy Designation may accelerate time-to-market, shortening the commercialisation timeline and potentially leading to earlier revenue generation.
• Pipeline Expansion: Ongoing trials in other cancers could multiply HB1901’s commercial potential, further enhancing CSPC’s growth outlook.

Corporate Governance

The announcement was made by Chairman Cai Dong Chen on behalf of the Board, which comprises a diverse group of executive and independent non-executive directors with deep expertise in pharmaceuticals, science, and business management.

Conclusion

The announcement of HB1901’s positive Phase Ib/III results and Breakthrough Therapy Designation is a potentially transformative event for CSPC Pharmaceutical Group. Investors should closely monitor regulatory updates, commercialization progress, and the advancement of related clinical programs, as these milestones may have a significant bearing on the company’s future share price and market position.

Disclaimer: This article is for informational purposes only and does not constitute investment advice. Readers should conduct their own research and consult professional advisors before making any investment decisions. The information is based on public disclosures as of 20 April 2026 and may be subject to change.

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