Simulations based on disease-progression models and phase II trial results can predict phase III results and have the potential to improve oncology drug development by informing end-of-phase II decisions (EOP2Ds). Many barriers impede effective use of modeling and simulation (M&S) for EOP2Ds in oncology: concerns about model validity, lack of access to M&S results and patient-level data, limited awareness of M&S among academic oncologists, and inexperience fitting M&S into the drug development timeline.