Biocytogen Announces Clinical Milestone with First Patient Dosed in Phase 1 Trial of IDEAYA's First-in-Class B7H3/PTK7 Bispecific TOP1 ADC IDE034

Biocytogen Pharmaceuticals (Beijing) Co., Ltd.

• IDE034 is a B7H3/PTK7 bispecific TOP1 ADC designed to target tumor cells expressing both B7H3 and PTK7 preferentially, and is being evaluated as monotherapy and in combination with IDEAYA’s PARG inhibitor IDE161.
• IDEAYA has dosed the first patient in its Phase 1 trial of IDE034, initially evaluating safety, tolerability, and PK.
• First dosing triggers a $5 million milestone payment to Biocytogen under the companies’ option and license agreement.

Biocytogen Pharmaceuticals (Beijing) Co., Ltd. (Biocytogen, SSE: 688796; HKEX: 02315), a global biotechnology company that drives the research and development of novel antibody-based drugs with innovative technologies, today announced that its partner IDEAYA Biosciences, Inc. (“IDEAYA”; Nasdaq: IDYA) has dosed the first patient in IDEAYA’s Phase 1 dose-escalation/expansion clinical trial of IDE034, an investigational B7H3/PTK7 bispecific TOP1 ADC. Pursuant to the companies’ option and license agreement, first patient dosing triggers a $5 million milestone payment to Biocytogen.

According to IDEAYA, the Phase 1 study is designed to characterize IDE034’s safety profile, tolerability, and PK as a monotherapy, and IDEAYA also intends to evaluate combination regimens with DNA damage response (DDR) -targeting agents such as its oral PARG inhibitor IDE161 as the program advances.

IDE034 is a potential first-in-class bispecific B7H3/PTK7 TOP1 ADC, independently developed by Biocytogen and licensed to IDEAYA in July 2024. IDEAYA has stated that IDE034 is designed to preferentially internalize in tumor cells co-expressing B7H3 and PTK7, supporting selectivity and tolerability, and estimates 30–40% co-expression across several major solid tumors with limited dual expression in normal tissues.

“Reaching first dosing in the IDE034 Phase 1 trial marks an important step in translating this bispecific TOP1 ADC concept into clinical evaluation,” said Dr. Yuelei Shen, President and CEO of Biocytogen. “We appreciate IDEAYA’s strong execution in advancing IDE034 into the clinic and look forward to the readout of initial safety and PK data from the ongoing Phase 1 study.”

About Biocytogen

Biocytogen (SSE: 688796; HKEX: 02315) is a global biotechnology company that drives the research and development of novel antibody-based drugs with innovative technologies. Founded on gene editing technology, Biocytogen has established a dual-engine platform combining a fully human antibody library with an extensive target-humanized mouse model portfolio, enabling a systematic approach to accelerating global drug discovery and development.

Biocytogen has independently developed its proprietary RenMice^® (RenMab^®/ RenLite^®/ RenNano^®/RenTCR™/ RenTCR mimic™) platforms for fully human monoclonal/bispecific/multispecific antibody discovery, bispecific antibody-drug conjugate discovery, hu-VHH discovery, and TCR mimic antibody discovery, and has established a sub-brand, RenSuper™ Biologics, to explore global partnerships for an off-the-shelf library of >1,000,000 fully human antibody sequences against over 1000 targets for worldwide collaboration. As of June 30, 2025, approximately 280 therapeutic antibody and multiple clinical asset co-development/out-licensing/transfer agreements and over 50 target-nominated RenMice^® licensing projects have been established around the globe, including several partnerships with multinational pharmaceutical companies (MNCs). Biocytogen pioneered the generation of drug target knock-in humanized models for preclinical research, and currently provides a few thousand off-the-shelf animal and cell models under the company's sub-brand, BioMice™, along with preclinical pharmacology and gene-editing services for clients worldwide. Headquartered in Beijing, Biocytogen has branches in China (Haimen, Jiangsu, Shanghai), the USA (Boston, San Francisco, San Diego), and Germany (Heidelberg). For more information, please visit https://biocytogen.com.

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