Abstract 2642: BL-B01D1, a novel EGFR×HER3-targeting ADC, demonstrates robust anti-tumor efficacy in preclinical evaluation

Abstract EGFR and HER3, members of the human epidermal growth factor receptor (ErbB) family, are targeted in cancer therapy due to their over-expression and pathway dependence in common human epithelial carcinoma tumors. To develop a promising therapeutic anti-tumor agent, we generated BL-B01D1, an EGFR×HER3-targeting ADC, which can bind to EGFR and/or HER3 positive cells and is expected to be superior to anti-EGFR and anti-HER3 ADCs. It is comprised of a bispecific antibody against EGFR/HER3 (SI-B001), a cathepsin B cleavable linker, and a novel topoisomerase I inhibitor agent (Ed-04), which is a derivative of the alkaloid camptothecin, driving cell cycle arrest at the S phase and subsequent apoptosis. BL-B01D1 achieves a high drug-to-antibody-ratio (DAR=8) with a highly stable linker. The pharmacological potential of this ADC was evaluated in comparison to its parental single antigen-targeting ADCs in xenograft models composed of either the human colorectal cancer cell line SW620 or pancreatic cancer cell line BxPC3. The tumor inhibition activity of BL-B01D1 was compared with ADCs prepared from each parental anti-EGFR or anti-HER3 mAb conjugated with the same linker and payload. The bispecific ADC, BL-B01D1 exhibited stronger tumor inhibition capacity than the anti-EGFR ADC and the anti-HER3 ADC separately. The preclinical studies suggest BL-B01D1, as an EGFR×HER3-targeting ADC, might be a promising novel agent with activity toward a broad range of human cancers. The clinical phase I has been progressing and the available data exhibit excellent efficacy but low levels of targeted toxicity in the non-small cell lung cancer (NSCLC) treatment setting. Overall, these data suggest BL-B01D1 has potential to serve as a novel, efficacious therapeutic agent for NSCLC with similar therapeutic impact as DS-8201 has in breast cancer treatment. Citation Format: Weili Wan, Shuwen Zhao, Shi Zhuo, Yong Zhang, Lan Chen, Gangrui Li, Blair Renshaw, Jahan Salar Khalili, Sa Xiao, Yi Zhu. BL-B01D1, a novel EGFR×HER3-targeting ADC, demonstrates robust anti-tumor efficacy in preclinical evaluation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2642.