July 30, 2026 – Shanghai Henlius Biotech, Inc. (2696.HK) announced that its second innovative T cell engager (TCE), HLX3902, a tri-specific antibody targeting STEAP1×CD3×CD28 developed on the company’s proprietary immune cell engager platform, has completed the first patient dosing in its first-in-human(FIH) study (HLX3902-FIH101) in China for the treatment of metastatic castration-resistant prostate cancer (mCRPC) and other advanced solid tumours. The study has also received clinical trial authorization in Australia. To accelerate early efficacy and safety evaluation of the product, the company has initiated multi-regional clinical trials (MRCT) simultaneously in China and Australia.
HLX3902 is an innovative trispecific antibody with proprietary intellectual property, capable of simultaneously engaging CD3 and CD28 to enhance T-cell-mediated killing of STEAP1-expressing tumour cells. By optimizing both the primary (CD3) and co-stimulatory (CD28) signals, HLX3902 promotes T-cell activation, proliferation, and survival, prolonging antitumor immune responses even in tumours with low T-cell infiltration.
Preclinical studies demonstrated that HLX3902 induces target-dependent T-cell activation and cytotoxicity, outperforming traditional CD3-based bispecific TCEs at low effector-to-target ratios. Repeated antigen stimulation models further confirmed that CD28 co-stimulation enhances T-cell activation, proliferation, and memory T-cell expansion, sustaining long-term cytotoxic effects. In vivo, HLX3902 showed significant antitumor activity in both C4-2/hPBMC and abiraterone-resistant PDX/hPBMC models, accompanied by increased T-cell infiltration and functional activity. In cynomolgus monkeys, HLX3902 demonstrated favourable tolerability and a controllable safety profile.
As a potentially first-in-class STEAP1-targeting trispecific T-cell engager, the development of HLX3902 validates the continued evolution of Henlius’ multispecific immune cell engager platform from technology construction to clinical translation. Previously, HLX3901, the Company’s first-in-class DLL3×CD3×CD28×CD28 tetravalent T-cell engager developed on the platform, demonstrated best-in-class potential in preclinical studies and has successfully completed first-in-human dosing, marking a key transition from platform establishment to clinical validation.
Looking forward, Henlius will remain committed to a patient-centric R&D philosophy and a systematic, platform-based innovation strategy to advance differentiated, globally competitive therapies, providing broader access to effective treatments for patients worldwide.
About HLX3902-FIH101
