Differentiated trispecific TIGIT-Fc ligand-trap strategy aims to address CD226 downregulation, a potential limitation of conventional anti-TIGIT antibodies

U.S FDA clearance followed by accelerated Taiwan TFDA approval advances HCB303 toward multi-regional Phase 1 clinical development

TAIPEI, SHANGHAI and SAN FRANCISCO, Oct. 30, 2026 /PRNewswire/ -- HanchorBio, Inc. (TWSE: 7827), a global clinical-stage biotechnology company developing next-generation immunotherapies for oncology and immune-mediated diseases, today announced that its wholly owned subsidiary, FBD Biologics Limited, has received approval from the Taiwan Food and Drug Administration (TFDA) for the Investigational New Drug (IND) application for HCB303, a next-generation trispecific fusion protein featuring a differentiated TIGIT-Fc ligand-trap strategy.

The TFDA approval follows U.S. FDA IND clearance, establishing regulatory authorization in both jurisdictions for HCB303's planned clinical investigation.

Unlike conventional anti-TIGIT antibodies that primarily act by blocking inhibitory signaling through the TIGIT receptor, HCB303 employs a differentiated TIGIT-Fc ligand-trap strategy designed to bind multiple TIGIT-associated ligands, including PVR/CD155 and CD112, potentially limiting ligand-mediated CD226 downregulation. Combined with PD-L1 blockade and SIRPα-mediated CD47 checkpoint inhibition, HCB303 aims to coordinate innate and adaptive antitumor immunity within a single engineered molecule.

"The future of immunotherapy will not be defined simply by adding more targets, but by understanding how those targets interact," said Scott Liu, Ph.D., Founder and Chairman of HanchorBio. "HCB303 represents that philosophy. Conventional anti-TIGIT antibodies block the receptor but leave shared ligands available to engage CD226, potentially contributing to its downregulation. We therefore designed a differentiated ligand-trap strategy intended to modulate inhibitory immune signaling while potentially reducing CD226 receptor downregulation and exploring the preservation of its immune-activating function. With U.S. FDA clearance followed by Taiwan TFDA approval, we are advancing this biology into globally coordinated clinical development. This is precisely the type of differentiated therapeutic architecture our FBDB™ platform was built to deliver."

Beyond Conventional Anti-TIGIT: Addressing the CD226 Challenge

Despite substantial interest in TIGIT-targeted cancer immunotherapy, disappointing results from several late-stage anti-TIGIT antibody trials have highlighted the pathway's complexity and the importance of maintaining activating immune signals.

TIGIT and CD226 are functionally interconnected receptors on T cells and natural killer (NK) cells. CD226 is an important activating receptor that shares ligands, including PVR/CD155 and CD112, with the inhibitory receptor TIGIT. Conventional anti-TIGIT antibodies block inhibitory TIGIT signaling but do not directly prevent shared ligands, including PVR/CD155 and CD112, from engaging CD226. However, sustained CD155 engagement can contribute to CD226 internalization and downregulation, potentially limiting immune activation.

HCB303 takes a different molecular design approach. Its TIGIT-Fc ligand-trap architecture is designed to bind shared ligands, including PVR/CD155 and CD112, with the aim of reducing ligand-mediated CD226 receptor internalization and downregulation, thereby potentially preserving CD226 cell-surface expression. However, whether preservation of receptor expression can further support CD226-mediated immune-activating signaling and translate into meaningful antitumor activity and clinical benefit remains to be established through subsequent clinical and translational studies.

HCB303 also integrates PD-L1 blockade and SIRPα-mediated CD47 checkpoint inhibition, aiming to coordinate macrophage, T-cell, and NK-cell antitumor responses within a single trispecific fusion protein.

Taiwan's Accelerated Regulatory Pathway Advances HCB303's Global Development

HCB303 received TFDA approval through Taiwan's accelerated review pathway for multinational, multicenter clinical trials. The streamlined procedure provides a 15-day review process for eligible applications, facilitating more efficient international clinical development.

TFDA has also simplified regulatory submission requirements for qualifying first-in-human studies, including removing the requirement to submit foreign participating hospitals' institutional review board approval letters under applicable conditions.

HCB303's progression from U.S. FDA IND clearance to accelerated Taiwan TFDA approval highlights HanchorBio's globally coordinated regulatory strategy, enabling more efficient advancement of differentiated immunotherapies into multinational clinical development.

From Differentiated Biology to Global Clinical Evidence

HanchorBio is preparing to advance HCB303 into its Phase 1 first-in-human, dose-escalation study (HCB303-ONC-101; NCT07859228) in patients with advanced, relapsed, or refractory solid tumors who have exhausted appropriate standard treatment options.

The study will evaluate safety, tolerability, pharmacokinetics, pharmacodynamics, immunogenicity, biomarkers, and preliminary antitumor activity. Translational assessments will investigate target engagement, immune modulation, and exposure-response relationships to inform dose optimization and subsequent clinical development.

These translational studies will also assess biomarkers related to CD226 receptor expression, TIGIT-associated ligands, and myeloid immune cells to explore how HCB303 modulates different immune cell populations and signaling pathways, and to evaluate whether its differentiated molecular design produces the intended biological effects in patients.

"The history of TIGIT drug development reminds us that a compelling story does not automatically translate into clinical benefit," said Alvin Luk, Ph.D., M.B.A., C.C.R.A., President and Chief Medical Officer (Group) and CEO (USA) of HanchorBio. "The challenge now is to determine whether HCB303's differentiated mechanism translates into meaningful activity in patients. Our Phase 1 study goes beyond conventional dose escalation by integrating clinical pharmacology, target engagement, immune biomarkers, and early antitumor activity. We need to understand not just HCB303's safety and pharmacology, but whether we see evidence of its intended biological effects, at what exposure, and in which patients it may offer the greatest potential benefit. That evidence will determine our next clinical development decisions."

Clinical trial initiation and patient enrollment will proceed in accordance with applicable regulatory requirements, institutional ethics approval, and clinical site readiness.

FBDB™ Platform: Expanding Differentiated Trispecific Therapeutics

HCB303 is HanchorBio's second FBDB™-derived trispecific immunotherapy to advance toward human clinical evaluation, following HCB301. While HCB301 integrates SIRPα, PD-L1, and TGF-β biology, HCB303 incorporates a distinct TIGIT-Fc ligand-trap strategy alongside SIRPα and PD-L1 modulation, illustrating the platform's versatility in generating differentiated multispecific therapeutic architectures.

About HCB303

HCB303 is an investigational, humanized trispecific fusion protein developed using HanchorBio's proprietary FBDB™ platform. It is designed to simultaneously modulate the SIRPα/CD47, PD-L1/PD-1, and TIGIT/PVR immune pathways, integrating macrophage, T-cell, and NK-cell antitumor immunity within a single engineered molecule. HCB303 is being developed as a potential treatment for advanced solid tumors. Its safety and efficacy have not been established.

About HanchorBio

HanchorBio (TWSE: 7827) is a global clinical-stage biotechnology company focused on inventing and developing next-generation biologics for cancer and immune-mediated diseases using its proprietary FBDB™ platform.

HanchorBio's pipeline includes HCB101, its lead SIRPα-based innate immune checkpoint program; HCB301, a clinical-stage trispecific immunotherapy targeting SIRPα, PD-L1, and TGF-β biology; HCB303, a clinical-stage trispecific immunotherapy integrating SIRPα/CD47, PD-L1/PD-1, and TIGIT/PVR biology; and additional programs across oncology and immune-mediated diseases. For more information, please visit: https://www.HanchorBio.com.

Forward-Looking Statements

This press release contains forward-looking statements regarding the clinical development of HCB303; the timing, initiation, design, conduct, and potential outcomes of future clinical studies; HCB303's proposed mechanisms, therapeutic characteristics, safety, and antitumor activity; potential preservation of CD226 expression or signaling; HanchorBio's global development strategy; and the capabilities and potential of the FBDB™ platform. These statements are based on current expectations and assumptions and involve risks and uncertainties that could cause actual results to differ materially from those described. U.S. FDA clearance and Taiwan TFDA approval authorize clinical investigation in accordance with applicable requirements but do not constitute marketing approval or establish the safety or efficacy of HCB303. Mechanistic hypotheses and preclinical observations may not translate into clinical benefit. There can be no assurance regarding the timing or success of clinical development or future regulatory approvals. HanchorBio undertakes no obligation to update forward-looking statements except as required by applicable law.

HanchorBio Business Development Contact:
Email: BD@HanchorBio.com

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SOURCE HanchorBio Inc.