Through integrated analyses of genetic and functional genomic data, we were the first to detect cancer vulnerabilities associated with copy-number losses (and invented an extremely convoluted acronym for them: CYCLOPS, standing for “Copy-number alterations Yielding Cancer Liabilities Owing to Partial losS”). We have shown that this is the most enriched class of dependencies associated with copy-number changes, and in one case, have identified a small molecule that exploits a CYCLOPS dependency, indicating a potentially generalizable approach to translating these vulnerabilities into treatments.