Data Demonstrate Activity in HER2-Low and ADC-Resistant Tumor Models, Supporting Advancement Toward IND

SHANGHAI and SUZHOU, China, April 14, 2026 /PRNewswire/ -- Phrontline Biopharma today announced the presentation of preclinical data for TJ106, a next-generation biparatopic HER2-targeting antibody-drug conjugate (ADC) with a dual-payload platform, at the American Association for Cancer Research Annual Meeting 2026.

The data demonstrate robust antitumor activity across HER2-expressing tumor models, including those with low or heterogeneous HER2 expression and models resistant to prior HER2-targeted therapies and antibody-drug conjugates, including Trastuzumab deruxtecan. These findings support the continued development of TJ106 as a potential treatment option for patients with HER2-expressing cancers who have progressed on existing therapies.

TJ106 is engineered with a biparatopic HER2 antibody designed to bind two distinct epitopes, promoting receptor clustering and enhancing internalization. This approach is intended to improve intracellular delivery of cytotoxic payloads and address limitations associated with heterogeneous HER2 expression and suboptimal uptake observed with earlier HER2-targeted therapies.

The molecule incorporates a dual-payload design combining a topoisomerase I inhibitor and a microtubule inhibitor. These payloads provide complementary and non-overlapping mechanisms of action, enabling sustained cytotoxic activity and the potential to overcome resistance associated with single-payload ADCs. In preclinical studies, TJ106 demonstrated consistent tumor growth inhibition across multiple models, including those previously exposed to HER2-directed therapies.

TJ106 also incorporates an optimized linker system designed to balance plasma stability with efficient intracellular payload release, supporting a favorable therapeutic window in preclinical evaluations.

"The data presented at AACR highlight the potential of TJ106 to address key challenges in HER2-targeted therapy, including resistance and tumor heterogeneity," said Martin S. Olivo, M.D., M.Sc., Chief Medical Officer of Phrontline Biopharma. "By combining biparatopic targeting with a dual-payload approach, TJ106 is designed to enhance tumor delivery and provide durable antitumor activity while maintaining an acceptable safety profile."

Phrontline plans to advance TJ106 into IND-enabling studies with an anticipated Investigational New Drug (IND) submission in early 2027. A global Phase I clinical trial is expected to evaluate TJ106 in patients with HER2-expressing solid tumors, including breast and gastric cancers, with a focus on patients previously treated with HER2-targeted therapies, including ADCs. The clinical program is expected to incorporate dose optimization principles aligned with U.S. Food and Drug Administration Project Optimus, including evaluation of exposure–response relationships and multi-cycle tolerability.

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About TJ106

TJ106 is an investigational biparatopic HER2-targeting antibody-drug conjugate (ADC) incorporating a dual-payload platform consisting of a topoisomerase I inhibitor and an eribulin-based microtubule inhibitor. The molecule is designed to enhance tumor targeting, internalization, and intracellular drug delivery to address resistance mechanisms in HER2-expressing cancers.

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About Phrontline Biopharma

Phrontline Biopharma is a clinical-stage oncology company focused on the development of next-generation antibody-drug conjugates (ADCs), including bispecific and dual-payload platforms, to address unmet needs in solid tumors.

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Forward-Looking Statements

This press release contains forward-looking statements regarding TJ106, including anticipated IND timing, clinical development plans, and therapeutic potential. These statements are subject to risks and uncertainties that may cause actual results to differ materially.