In partnership with AstraZeneca and the Sanger Institute, we are pleased to announce that the AstraZeneca-Sanger Drug Combination Prediction DREAM Challenge is now open! This Challenge will ask participants to develop predictive models of drug combination synergy across a large panel of cancer cell lines. In contrast to our previous DREAM Challenge on drug synergy, this Challenge will utilize a much larger drug screen with over 11,000 combinations. Multiple data types will be available to participants including single agent sensitivity, somatic mutations, copy-number alterations, DNA methylation, and gene expression.