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Nat Chem Biol. 2019 Aug 26. doi: 10.1038/s41589-019-0342-2. [Epub ahead of print]

CRISPR-Cas9 screens identify regulators of antibody-drug conjugate toxicity.

Author information

1
Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA.
2
Catalent Biologics, Emeryville, CA, USA.
3
Stanford ChEM-H, Stanford University, Stanford, CA, USA.
4
Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA.
5
Department of Chemistry, Stanford University, Stanford, CA, USA.
6
Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA.
7
Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA. bassik@stanford.edu.
8
Stanford ChEM-H, Stanford University, Stanford, CA, USA. bassik@stanford.edu.

Abstract

Antibody-drug conjugates (ADCs) selectively deliver chemotherapeutic agents to target cells and are important cancer therapeutics. However, the mechanisms by which ADCs are internalized and activated remain unclear. Using CRISPR-Cas9 screens, we uncover many known and novel endolysosomal regulators as modulators of ADC toxicity. We identify and characterize C18ORF8/RMC1 as a regulator of ADC toxicity through its role in endosomal maturation. Through comparative analysis of screens with ADCs bearing different linkers, we show that a subset of late endolysosomal regulators selectively influence toxicity of noncleavable linker ADCs. Surprisingly, we find cleavable valine-citrulline linkers can be processed rapidly after internalization without lysosomal delivery. Lastly, we show that sialic acid depletion enhances ADC lysosomal delivery and killing in diverse cancer cell types, including with FDA (US Food and Drug Administration)-approved trastuzumab emtansine (T-DM1) in Her2-positive breast cancer cells. Together, these results reveal new regulators of endolysosomal trafficking, provide important insights for ADC design and identify candidate combination therapy targets.

PMID:
31451760
DOI:
10.1038/s41589-019-0342-2

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