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bioRxiv · 10.1101/2022.08.11.503187

An antibody-drug conjugate targeting GPR56 demonstrates efficacy in preclinical models of colorectal cancer

Jacob, J.·Francisco, L. E.·Chatterjee, T.·Liang, Z.·Subramanian, S.·Liu, Q. J.·Rowe, J. H.·Carmon, K. S.
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Abstract

Antibody-drug conjugates (ADCs) have become an increasingly successful class of anticancer therapy, particularly within the past few years. Though ADCs are in clinical trials for colorectal cancer (CRC), a candidate has yet to be approved. CRC continues to be a leading cause of cancer-related death, emphasizing the need to identify novel target antigens for ADC development. GPR56, a member of the 7TM receptor family, is upregulated in colorectal tumors compared to normal tissues and located on the surface of CRC cells, making it a promising ADC target. Furthermore, high GPR56 expression occurs in tumors that are microsatellite stable, negative for the CpG methylator phenotype, and show chromosomal instability. We previously reported the generation of a high affinity GPR56-specific monoclonal antibody, 10C7, and we have now mapped the epitope to the C-terminal end of the extracellular domain, proximal to the GPCR proteolysis site. Here, we describe the development of a duocarmycin-conjugated 10C7 ADC. 10C7 co-internalized with GPR56 and trafficked to the lysosomes of CRC cells, which is critical for efficient ADC payload release. Evaluation of the ADC in a panel of CRC cell lines and tumor organoids with different levels of GPR56 expression showed the ADC selectively induced cytotoxicity at low nanomolar concentrations in a GPR56-dependent manner. A nontargeting control ADC showed minimal to no activity. Furthermore, GPR56 ADC exhibited significant antitumor efficacy against GPR56-expressing patient-derived xenograft models of CRC. This study provides rationale for the development of a GPR56-targeted ADC approach to potentially treat a large fraction of CRC patients.

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Jacob, J., Francisco, L. E., Chatterjee, T., Liang, Z., Subramanian, S., Liu, Q. J., Rowe, J. H., Carmon, K. S.. 2022-08-14. An antibody-drug conjugate targeting GPR56 demonstrates efficacy in preclinical models of colorectal cancer. https://doi.org/10.1101/2022.08.11.503187

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