CAMBRIDGE, Mass., ROTTERDAM, Netherlands and SHANGHAI, July 29, 2025 — Harbour BioMed (HKEX: 02142), a global biopharmaceutical firm specializing in the discovery and development of innovative antibody therapies for immunology and oncology, today disclosed its plan to present Phase II clinical data for its next-generation, fully human heavy-chain-only anti-CTLA-4 antibody, porustobart (HBM4003), when administered in combination with tislelizumab, for the treatment of microsatellite stable (MSS) metastatic colorectal cancer (mCRC). The presentation is scheduled for the ESMO Congress 2025, which will be held from October 17-21, 2025, in Berlin, Germany.
MSS mCRC continues to be a therapeutic challenge, showing limited responsiveness to immune checkpoint inhibitors. Preclinical evidence indicates synergistic anti-tumor activity when CTLA-4 blockade is combined with PD-(L)1 inhibition in mouse models. This multicenter, open-label Phase II study () enrolled heavily pretreated non-liver metastatic MSS mCRC patients. Preliminary data on both efficacy and safety will be shared during a poster session at the ESMO Congress 2025.
The details for the poster presentation are as follows:
Title: Efficacy and Safety of HBM4003, an anti-CTLA-4 Antibody, Combined with Tislelizumab in MSS Metastatic Colorectal Cancer: A Multicenter, Phase II Study
Presentation Number: 807P
Speaker: Frank Zheng
All accepted abstracts will be made available online on the .
About Porustobart (HBM4003)
Porustobart (HBM4003) is an advanced, fully human heavy-chain-only anti-CTLA-4 antibody discovered and developed utilizing the HCAb Harbour Mice® platform. It also holds the distinction of being the first fully human heavy-chain-only antibody to enter global clinical development. Compared to conventional CTLA-4 antibodies, porustobart possesses distinct, advantageous characteristics, including significant Treg cell depletion and optimized pharmacokinetics for enhanced safety. Additionally, by boosting antibody-dependent cellular cytotoxicity (ADCC), porustobart amplifies the potential to selectively deplete intratumoral Treg cells, thereby aiding in overcoming the efficacy and toxicity limitations of existing CTLA-4 therapies. Harbour BioMed has implemented a comprehensive global development plan for porustobart, addressing multiple types of solid tumors with an adaptive treatment design. Favorable efficacy and safety data have been observed in monotherapy trials targeting advanced solid tumors, as well as in combination trials with PD-1 inhibitors for melanoma, CRC, NEN, and HCC.
About Harbour BioMed
Harbour BioMed (HKEX: 02142) is a global biopharmaceutical enterprise dedicated to the discovery and development of innovative antibody therapeutics in immunology and oncology. The company is actively building a robust and differentiated pipeline through its internal R&D capabilities, strategic global collaborations in co-discovery and co-development, and targeted acquisitions.
Harbour BioMed’s proprietary antibody technology platform, Harbour Mice®, generates fully human monoclonal antibodies in both the conventional two heavy and two light chain (H2L2) format and the heavy chain-only (HCAb) format. Building upon HCAb antibodies, the HCAb-based immune cell engagers (HBICE®) bispecific antibody technology enables tumor-killing effects that traditional combination therapies cannot achieve. Additionally, the HCAb-based bispecific immune cell antagonist (HBICATM) technology empowers the development of innovative biologics for immunological and inflammatory diseases. By integrating Harbour Mice®, HBICE®, and HBICATM with a single B-cell cloning platform, Harbour BioMed has established an exceptionally efficient and distinctive engine for discovering and developing cutting-edge therapeutic antibodies. For further details, please visit .
SOURCE Harbour BioMed