Most of these were established dependencies of cancer cells, including Nutlin‐3a sensitivity and MDM2 gene fitness independently associated with TP53 mutation status; BRAF and PIK3CA mutation induced drug and CRISPR dependency; olaparib sensitivity mediated by the presence of EWSR1‐FLI1 fusion, also recapitulated by FLI1 essentiality profile; MCL1 inhibitor and gene fitness associations with BCL2L1 expression, and Nutlin‐3a sensitivity and MDM2 gene fitness associated with BAX expression (Figs 5C and EV5E and F). Here, PIK3CA is linked to cancer.