Imputed lapatinib response in TCGA breast cancer patients. (A) A boxplot showing the value for imputed lapatinib response in all TCGA breast cancer patients, where ERBB2 status was measured by immunohistochemistry. The imputed drug response data are consistent with how this drug behaves clinically (P = 6.7 × 10⁻¹³). Note that lower values on the y-axis imply greater drug sensitivity. (B) A histogram of P-values achieved for all 138 drugs when imputed drug response is compared between ERBB2+ and ERBB2− breast cancer patients in TCGA. Lapatinib, the only one of these drugs known to be differentially effective between these cohorts in the clinic, achieves the strongest association, suggesting that drug response is being accurately imputed.