Highlights d Living biobank includes 17 normal and 46 gastric cancer organoid lines d Organoid biobank encompasses most of the known molecular subtypes of gastric cancer d Organoids recapitulate the genomic and transcriptomic features of original tumors d High-throughput screen revealed potential target drugs for personalized therapy

SUMMARY Current anti-mitotics work by perturbing spindle assembly, which activates the spindle assembly checkpoint, causes mitotic arrest, and triggers apoptosis. Cancer cells can resist such killing by premature exit, before cells initiate apoptosis, due to a weak checkpoint or rapid slippage. We reasoned blocking mitotic exit downstream of the checkpoint might circumvent this resistance. Using single-cell approaches, we showed that blocking mitotic exit by Cdc20 knockdown slowed cyclin B1 proteolysis, thus allowed more time for death initiation. Killing by Cdc20 knockdown did not require checkpoint activity, and can occur by intrinsic apoptosis, or an alternative death pathway when Bcl2 was over-expressed. We conclude targeting Cdc20, or otherwise blocking mitotic exit, may be a better cancer therapeutic strategy than perturbing spindle assembly.

To improve cancer chemotherapy, we need to understand the mechanisms that determine drug sensitivity in cancer and normal cells. Here, we investigate this question across a panel of 11 cell lines at a phenotypic and molecular level for three antimitotic drugs: paclitaxel, nocodazole, and an inhibitor of kinesin-5 (also known as KSP, Eg5,