TJ Biopharma Doses First Patient in Phase 1 Trial of TJ-C64B, a CLDN6x4-1BB Bispecific Antibody for CLDN6-Positive Solid Tumors

- TJ-C64B is an internally developed CLDN6 × 4-1BB bispecific antibody for which TJ Biopharma retains global rights, and is among the leading programs in this class globally

- First patient dosing marks a key milestone for TJ Biopharma's next-generation innovation pipeline

HANGZHOU, China, Oct. 26, 2026 /PRNewswire/ -- TJ Biopharma ("TJ Bio" or "the Company"), a fully integrated biotech company focusing on discovery, development, manufacturing and commercialization of innovative biologics in the areas of autoimmune diseases, oncology and metabolic disorders, today announced that the first patient has been dosed in a Phase 1 clinical trial of TJ-C64B, a novel Claudin 6 (CLDN6) × 4-1BB bispecific antibody, in patients with CLDN6-positive advanced solid tumors.

CLDN6 is selectively expressed in multiple solid tumors, including ovarian cancer, endometrial cancer, gastric cancer, and certain lung cancers, while showing minimal expression in normal adult tissues. CLDN6-positive tumors are often associated with poor prognosis, highlighting a significant unmet medical need for targeted therapeutic approaches.

TJ-C64B is a next-generation CLDN6 × 4-1BB bispecific antibody generated from the Company's proprietary Antibody^PLUS platform. Designed using a conditional 4-1BB activation approach, TJ-C64B relies on CLDN6 to localize 4-1BB agonistic activity within the tumor microenvironment. This CLDN6-dependent mechanism is intended to drive potent anti-tumor immunity while minimizing the systemic immune toxicities associated with conventional 4-1BB agonists.

TJ-C64B incorporates a functional IgG1 Fc domain and is designed to engage multiple anti-tumor mechanisms, including CLDN6-dependent 4-1BB activation, antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and selective depletion of tumor regulatory T cells. Preclinical studies demonstrated CLDN6-dependent 4-1BB activation within tumors and potent, durable anti-tumor activity across multiple tumor models. Non-clinical safety studies further supported a favorable tolerability profile and the potential for clinical development.

The Phase 1 study is designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary anti-tumor activity of TJ-C64B in patients with CLDN6-positive advanced solid tumors. The study will initially evaluate TJ-C64B monotherapy in dose escalation cohorts, followed by dose expansion studies in selected tumor types, including ovarian cancer, endometrial cancer, and gastric cancer.

"Patients with CLDN6-positive tumors currently have few targeted treatment options and often face poor outcomes," said Professor Jin Li, Principal Investigator of the TJ-C64B Phase 1 study, President and Chief Scientist of Shanghai GoBroad Cancer Hospital affiliated with China Pharmaceutical University. "TJ-C64B adopts a CLDN6-dependent conditional 4-1BB activation mechanism, providing a promising approach to achieve more precise immune activation within tumors. Early clinical studies are critical to translating innovative scientific concepts into potential clinical benefits for patients. We are excited to advance this novel molecule into the clinic and support its high-quality and efficient development leveraging our clinical research capabilities."

"Dosing the first patient with TJ-C64B marks an important milestone for the Company as our next-generation innovation pipeline advances into clinical development," said Dr. Xi Chen, Chief Scientific Officer of TJ Bio. "TJ-C64B is an internally discovered asset for which TJ Bio retains global rights, and we are committed to advancing it efficiently through clinical development. TJ-C64B is one of several next-generation programs we are advancing into the clinic across multispecific antibodies, immunocytokines, and antibody-small molecule conjugates, building on the momentum of our first-wave products toward commercialization."

About TJ-C64B

TJ-C64B is an internally discovered CLDN6 × 4-1BB bispecific antibody developed by TJ Biopharma. The molecule is designed to activate 4-1BB locally within CLDN6-expressing tumors, engaging multiple immune effector cells, including T cells, natural killer (NK) cells, and macrophages, to drive anti-tumor immune responses. Its functional IgG1 Fc domain enables ADCC and ADCP activity, supporting direct elimination of CLDN6-positive tumor cells and 4-1BB-high regulatory T cells within the tumor microenvironment.

TJ-C64B is currently being investigated for the treatment of CLDN6-positive ovarian cancer, endometrial cancer, gastric cancer, and other advanced solid tumors.

About TJ Biopharma

TJ Biopharma is a fully integrated biotech company advancing next-generation therapies in autoimmune diseases, immuno-oncology and metabolic disorders. Anchored by comprehensive R&D centers in Shanghai and Beijing and a state-of-the-art GMP manufacturing facility in Hangzhou, the Company has built a clearly differentiated two-wave pipeline. The first wave includes products currently under regulatory review, together with additional late-stage assets in registrational or pre-Phase 3 development, while the second wave comprises novel antibody conjugates with first-in-class potential powered by the Company's proprietary Antibody^PLUS technology platforms, with programs advancing through Phase 1 studies or preparing for clinical entry. Over the years, TJ Biopharma has established a robust network of development and commercialization partnerships with Jumpcan, CSPC, Sanofi, Biogen and other leading industry players. The Company is committed to delivering innovation through a diversified and sustainable revenue model that integrates global asset transactions, contract manufacturing services, and future product sales. For more information, please visit TJBio.com or follow us on LinkedIn.

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SOURCE TJ Biopharma