UPDATE: First Patient Treated With ICP-B381, a Dual-Target PSMA/STEAP1 Antibody-Drug Conjugate

The experimental bispecific antibody-drug conjugate ICP-B381 has officially entered clinical testing, with the first patient dosed in China.

ICP-B381 is designed to recognize two prostate cancer-associated proteins, PSMA and STEAP1, while delivering a cytotoxic payload through an irreversible linker. Its dual-targeting mechanism aims to address tumor heterogeneity, a major challenge in advanced prostate cancer, where malignant cells may express different levels of individual therapeutic targets.

Earlier preclinical experiments showed promising activity in prostate cancer models with relatively low expression of both antigens. In a 22Rv1 xenograft model, ICP-B381 achieved approximately 94% tumor-growth inhibition at 1 mg/kg, compared with approximately 81% and 73% for the corresponding single-target STEAP1 and PSMA ADCs, respectively.

The initial study includes patients with advanced solid tumors, including prostate cancer, rather than exclusively men with metastatic castration-resistant disease.

Source.