Summary Whole genome doubling (WGD) occurs early in tumorigenesis and generates genetically unstable tetraploid cells that fuel tumor development. Cells that undergo WGD (WGD + ) must adapt to accommodate their abnormal tetraploid state; however, the nature of these adaptations, and whether they confer vulnerabilities that can subsequently be exploited therapeutically, is unclear. Using sequencing data from ∼10,000 primary human cancer samples and essentiality data from ∼600 cancer cell lines, we show that WGD gives rise to common genetic traits that are accompanied by unique vulnerabilities. We reveal that WGD + cells are more dependent on spindle assembly checkpoint signaling, DNA replication factors, and proteasome function than WGD − cells. We also identify KIF18A , which encodes for a mitotic kinesin, as being specifically required for the viability of WGD + cells. While loss of KIF18A is largely dispensable for accurate chromosome segregation during mitosis in WGD − cells, its loss induces dramatic mitotic errors in WGD + cells, ultimately impairing cell viability. Collectively, our results reveal new strategies to specifically target WGD + cancer cells while sparing the normal, non-transformed WGD − cells that comprise human tissue.

Whole genome doubling confers unique genetic vulnerabilities on tumor cells