Shanghai, China, April 10, 2026 – Henlius (2696.HK) today announced that the first patient has been dosed in China in HLX319-001, a phase 1 clinical trial of HLX319, the company's self-developed, fixed-dose subcutaneous injection of pertuzumab and trastuzumab. As a fixed-dose subcutaneous combination, HLX319 allows trastuzumab and pertuzumab administration in 5 minutes without weight-based dose adjustment, offering comparable efficacy and safety to intravenous regimens and greatly facilitating clinical use. Due to the technical complexity of developing stable large-molecule co-formulations, as well as patent constraints related to subcutaneous delivery systems and hyaluronidase excipient, no domestically developed subcutaneous combination product has yet been approved in China.
HLX319 is a biosimilar of Phesgo® developed by Henlius in compliance with Chinese and EU biosimilar guidelines. It contains the active ingredients trastuzumab and pertuzumab, along with a proprietary recombinant human hyaluronidase (rHuPH20) excipient. Phesgo® is first approved in 2020 and now marketed in China, the U.S., and the EU. The pertuzumab and trastuzumab used in HLX319 are Henlius’ self‑developed HLX11 and HANQUYOU, respectively. HLX319-001 is a randomized, double-blind, single-dose subcutaneous administration, parallel-controlled phase 1 clinical trial aimed at evaluating the pharmacokinetic (PK) characteristics, safety, tolerability, and immunogenicity of HLX319 and EU-Phesgo®(European commercial pertuzumab and trastuzumab injection (subcutaneous injection) in healthy Chinese male subjects.
The successful development of HLX319 highlights Henlius' integrated R&D capabilities, built upon extensive experience with trastuzumab, pertuzumab, and other biologics, as well as its forward-looking strategy in innovative technologies. As the key component enabling the subcutaneous delivery system, the hyaluronidase excipient in HLX319 is based on Henlius' proprietary hyaluronidase, Henozye®. It works by locally and reversibly degrading hyaluronic acid in the subcutaneous tissue, temporarily reducing resistance and allowing larger injection volumes while improving the dispersion and absorption of large molecule drugs. Since 2020, the company has been advancing its AI for Science platforms including HAI PBD, which integrates computational biology, mechanistic modeling, machine learning, and extensive experimental data. This AI-assisted platform spans key processes from protein modeling and design to process and formulation development, significantly boosting R&D efficiency.
Compared with conventional approaches, Henozye® enables a substantially shortened development cycle and demonstrates strong compatibility across diverse modalities, including monoclonal antibodies, bispecific and multispecific antibodies, fusion proteins, and antibody-drug conjugates (ADCs). Its excellent stability across various buffer systems and environmental conditions significantly lowers the barriers to subcutaneous co-formulation development, enhances the success rate of complex formulations, and expands the potential applications of diverse therapeutic modalities. Currently, Henozye® has been filed as a pharmaceutical excipient with China’s Center for Drug Evaluation (CDE; Registration No.: F20250000716) and as a Drug Master File (DMF) with the U.S. FDA. A IND application for the hyaluronidase injection was also recently approved by the NMPA to further evaluate its safety, pharmacokinetics, and immunogenicity in clinical study.
Breast cancer is the second most common malignancy worldwide and the leading cause of cancer in women1. HER2‑positive breast cancer accounts for approximately 15‑20% of all breast cancer cases2. In the field of HER2‑positive breast cancer therapy, Henlius has built a comprehensive portfolio covering the full treatment continuum. Its pipeline includes foundational regimens HANQUYOU (trastuzumab, trade name: HERCESSI™ in the U.S, Zercepac® in Europe) and HLX11 (pertuzumab, trade name: POHERDY® in the U.S.), the extended adjuvant therapy HANNAIJIA (neratinib) ,novel epitope anti-HER2 mAb HLX22 (dulpatatug*) and HER2 dual-epitope ADC HLX49. To date, HANQUYOU has been approved in more than 50 countries and regions worldwide, covering major markets in Europe and the United States as well as numerous emerging markets. HLX11 was approved by the FDA in November 2025 for the neoadjuvant/adjuvant treatment of HER2-positive early breast cancer and for HER2-positive metastatic breast cancer, making it the first and only pertuzumab biosimilar approved in the U.S.**. Its marketing authorization applications have also been accepted for review by the NMPA, Health Canada, and the European Medicines Agency (EMA).
Moving forward, Henlius will continue to deepen its focus on core disease areas such as breast cancer, lung cancer, and gastrointestinal cancers. By consistently strengthening its technical capabilities in Chemistry, Manufacturing, and Controls (CMC) and leveraging a multi-dimensional innovation platform—including next-generation immuno-oncology platform, immune cell engager, Hanjugator™ ADC, and HAI Club—the company aims to accelerate the development of a globally competitive product portfolio, delivering more high-quality and affordable treatment options for patients worldwide.
About HLX319-001
This study is a randomized, double-blind, single-dose subcutaneous administration, parallel-controlled phase 1 clinical trial aimed at evaluating the pharmacokinetic (PK) characteristics, safety, tolerability, and immunogenicity of HLX319 and EU-Phesgo® (European commercial pertuzumab and trastuzumab injection (subcutaneous injection)) in healthy Chinese male subjects. Eligible subjects will be randomized in a 1:1 ratio into two groups to receive either HLX319 or EU-Phesgo® as a single-dose, single-administration subcutaneous injection. The injection will be administered into the subcutaneous tissue of the thigh over approximately 5 minutes. The primary endpoints of this study are the key PK parameters of pertuzumab and trastuzumab, including maximum concentration (Cmax) and area under the serum concentration-time curve from time zero to infinity (AUC0-∞). Secondary endpoints include other PK parameters (such as area under the concentration-time curve from time zero to the time of the last quantifiable concentration (AUC0-t], time to maximum concentration (Tmax], elimination half-life (t1/2]), safety endpoints (such as adverse events, serious adverse events, vital signs, laboratory tests), and immunogenicity endpoints (such as the positivity rates of anti-drug antibodies (ADA])and neutralizing antibodies (Nab]).
References
1.https://www.who.int/news/item/01-02-2024-global-cancer-burden-growing--amidst-mounting-need-for-services.
2.Kang S,Lee SH,Lee HJ,et al.Pathological complete response,long-term outcomes,and recurrence patterns in HER2-low versus HER2-zero breast cancer after neoadjuvant chemotherapy. Eur J Cancer.2022 Sep 29;176:30-40.
* 药品通用名处于pINN状态
** U.S. FDA官网，访问日期：2026年3月31日