Shanghai, China, September 26, 2025 - Shanghai Henlius Biotech, Inc. (2696.HK) announced that the first subject was dosed for a phase 1 multi-centre clinical trial (HLX17-MRST001) of the company's independently developed investigational pembrolizumab biosimilar HLX17 (recombinant anti-PD-1 humanized antibody injection) in China. Previously, the investigational new drug (IND) applications of HLX17-MRST001 have been approved by the U.S. Food and Drug Administration (FDA) and the National Medical Products Administration (NMPA) as an adjuvant therapy for certain resected solid tumors.

HLX17 is a pembrolizumab biosimilar independently developed by Henlius in accordance with the NMPA, EMA, FDA and other international biosimilar guidelines. The pharmacologic comparative study, and preclinical pharmacology study, pharmacodynamics, pharmacokinetics and immunogenicity studies have demonstrated that HLX17 is similar to the reference pembrolizumab. Pembrolizumab has been approved in various countries and regions for a range of different indications, such as for the adjuvant treatment of non-small cell lung cancer (NSCLC), melanoma, and renal cell carcinoma (RCC).

HLX17-MRST001 is a multicenter, randomized, double-blind, parallel-controlled Phase 1 study evaluate the similarity of pharmacokinetic profile, efficacy, safety and immunogenicity of HLX17 vs. KEYTRUDA^® (US-sourced) in patients with multiple resected solid tumors (including non-small cell lung cancer, melanoma, or renal cell carcinoma). Eligible subjects will be randomized in a 1:1 ratio to either Arm A or Arm B, where subjects in Arm A will receive HLX17 once every 3 weeks, and those in Arm B will first receive KEYTRUDA^® once every 3 weeks for 8 cycles (24 weeks) before switching to HLX17 treatment, with all subjects continuing treatment until 12 months after the randomization (nearly 17 cycles), Investigator-assessed disease recurrence, death, initiation of new anti-tumor therapy, unacceptable toxicity, withdrawal of informed consent, or study termination (whichever occurs first). The primary PK endpoints are the area under the serum drug concentration-time curve from time 0 to 21 days (AUC_0-21d) after the first dose and the area under the serum drug concentration-time curve within a dosing interval at steady state (AUC_ss) after the sixth dose. Secondary endpoints include other PK parameters, other efficacy assessments, safety, and immunogenicity.

Looking forward, Henlius will maintain its focus on unmet medical needs and further broaden the company’s layout in more disease areas, commit to bring high quality and affordable treatments for patients worldwide.