It was not a random choice, but was based on a knowledge of the mechanisms underlying that particular cancer. It has recently become clear that cancer is not just one disease, and that it can not even be divided as simply as breast cancer, skin cancer, leukemia, etc. In the past, cancers were usually classified by criteria that were apparent to a clinician, such as the typical course of the disease, or to a pathologist, who makes decisions based on what a tumor looks like through a microscope. And what they are finding is that there are a huge number of changes that can cause cancerous behavior. Identifying the nature of these changes gives them clues as to how to tailor strategies for combating cancer that are specific and targeted to the changes within those particular cells.
Targeted strategies are much more effective than current therapies.
In the case of this leukemia, Dr. Evans and his group found that a pathway involving the retinoic acid derivative is disrupted. The key point is that identifying changes inside the cell gave the investigators an idea for a way to fix it. Fortunately, it turned out that the strategy they devised worked in the laboratory, and it also works in people suffering from this disease.