Unfortunately, not all oncology trials succeed. In fact, the phase success and likelihood of approval (LOA) rates for oncology are the lowest across major therapeutic areas. Although there are many reasons for these relatively poor success rates, issues determining dose, schedule, and regimen in early phase trials are among the most prominent.
Why and Where Early Oncology Trials Fail
The main failure in oncology trials happens in Phase 2. According to research published by M. Hay et al. in 2014, oncology trials have phase success and LOA rates comparable to other therapeutic areas, such as infectious disease and endocrinology, between Phase I and II trials. It's between Phases 2 and 3 that success rates for oncology dip, a discrepancy that is then compounded in the following Phase 3 to regulatory approval transition.