Some 90% of drugs that enter Phase I trials fail to reach the market, for a host of reasons. But while many of these drop-outs have efficacy and toxicity issues that genuinely preclude approval, others fall by the wayside because of human error and poor development plans. Tatiana Prowell, Breast Cancer Scientific Lead in the US Food and Drug Administration (FDA)' s Office of Hematology & Oncology Products, is among those now taking a stand against the common pitfalls that plague oncology drug development. Many of the top mistakes, she tells Asher Mullard, are easily avoided.