While cancer death rates have declined for some cancers, cancer remains a major public health problem, causing over 600,000 deaths per year in the US alone. Recent progress includes better understanding of cancer at the molecular level, leading to more targeted and personalized therapies. However, fewer patients enroll in clinical trials and many drug candidates fail in late-stage trials due to challenges including a lack of predictive animal models and the high cost of large trials. There is pressure to find cheaper and earlier answers on drug efficacy through biomarkers and trial design innovations to improve the challenging process of bringing new cancer treatments to patients.