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,  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.”