IDEAYA Biosciences announces first-patient-in for Phase 1 trial of IDE034, a potential first-in-class B7H3/PTK7 bispecific TOP1 ADC

CAR-T Digest - August 2020

Weekly Digest - February 2026

25 February 2026: IDEAYA Biosciences announces first-patient-in for Phase 1 trial of IDE034, a potential first-in-class B7H3/PTK7 bispecific TOP1 ADC

IDEAYA Biosciences announced that the first patient has been enrolled in a Phase 1 dose escalation and expansion trial evaluating IDE034, a potentially first-in-class B7H3/PTK7 bispecific TOP1 antibody–drug conjugate
The Phase 1 study is designed to assess safety, tolerability, and pharmacokinetics of IDE034 as a monotherapy, with planned future evaluation in combination with DNA damage response–targeting agents, including IDEAYA’s proprietary PARG inhibitor IDE161. The first patient dosed also triggered a $5 million milestone payment to Biocytogen under the company’s existing licensing agreement
IDE034 is engineered to be internalized only when both B7H3 and PTK7 are co-expressed on the same tumor cell, a design intended to enhance tumor selectivity and improve tolerability compared with traditional single-target ADC approaches
Preclinical studies have shown promising monotherapy activity and potential synergy when combined with IDE161, positioning IDE034 as part of IDEAYA’s broader strategy to integrate selective TOP1 ADCs with DDR pathway inhibitors to expand treatment options for patients with hard-to-treat cancers
The company estimates that B7H3 and PTK7 are co-expressed in approximately 30–40% of several major solid tumors, including lung, breast, ovarian, and colorectal cancers, while dual expression in normal tissues is limited, supporting its precision medicine strategy