Phase 1 Trial: Dual-Target ADC IDE034 Targets B7-H3/PTK7 in Prostate Cancer

A promising new bispecific antibody-drug conjugate (ADC) known as IDE034 is entering early clinical testing in patients with advanced solid tumors, including prostate cancer, marking a potential step forward in precision oncology. This Phase 1a/1b trial, which began dosing its first patient in February 2026, targets tumors expressing both B7-H3 and PTK7, two surface proteins overexpressed in aggressive malignancies. By linking a Topoisomerase I (TOP1) inhibitor payload to a bispecific antibody that binds these dual antigens, IDE034 aims to deliver its toxic cargo selectively to cancer cells, sparing healthy tissues that lack co-expression of both targets.

Prostate cancer inclusion stands out given B7-H3’s established role as an immunosuppressive checkpoint and prognostic marker in this disease. Studies show B7-H3 expression remains high and stable across primary tumors, hormone-refractory states, and bone metastases, even under androgen deprivation, correlating with faster progression and resistance.

B7-H3 (CD276) shows high membranous expression in 93%+ of castration-resistant prostate cancer (CRPC) cases and 97% of castration-sensitive cases.

PTK7, a pseudokinase often upregulated in prostate and other epithelial cancers, complements this profile, with co-expression patterns positioning IDE034 for mCRPC or earlier lines where AR inhibitors fall short. One key study found high PTK7 expression in about 63% of prostate cancer cases versus only 8% in BPH.

Preclinical models demonstrate deep tumor regressions in B7-H3/PTK7-positive xenografts, fueling optimism for clinical translation.

What elevates IDE034’s potential is its bispecific engineering, which preclinical work suggests boosts selectivity over single-target ADCs, potentially widening the therapeutic window for TOP1 payloads already proven in other indications. Plans to pair it with DNA damage response inhibitors could further amplify efficacy by trapping TOP1-DNA complexes, mirroring PARP inhibitor synergies but targeting PARylation pathways.

Clinical trial.