[gdpawel]

The era of personalized medicine based on validated tumor biomarkers is indeed at hand. As the increasing numbers and types of cancer drugs are developed, oncologists become more and more likely to misuse them in their practice. Developing a good and clinically practical drug selection system is no less important than the discovery of new drugs or how to put them into the body.

The idea of simply finding a mutation and then pick an appropriately targeted drug seems like a nice idea. However, not every key that looks like it will fit a lock will actually turn it. The same is likely to be the case with targeted drugs. There are numerous common mutations in various tumor types, but they don't know that all those mutations are going to turn out to be relevant, as many of them are essentially bystanders.

All the mutation or amplification studies tell us is whether or not the cells are potentially susceptible to a mechanism of attack. They don't tell you if one drug is better or worse than some other drug which may target this. The cell is a system, an integrated, interacting network of genes, proteins and other cellular constituents that produce functions. You need to analyze the systems' response to drug treatments, not just one target or pathway.

Giving instructions on the genetic differences that determine how a person responds to a drug will still have cancer medicine being prescribed on a trial-and-error basis, with adverse drug reactions remaining a major cause of injury and hospitalizations.

There have been technologies, developed over the last twenty years, that hold the key to solving some of the problems confronting a healthcare system that is seeking ways to best allocate available resources while accomplishing the critical task of matching individual patients with the treatments most likely to benefit them.

It isn't just molecular analysis, it is whether the capacity to judge phenotypes will be easily achieved at the genotype level. Systems biology suggests that the simple knowledge of a gene's presence or absence does not confer a biological behavior. No good gardener would attempt to tell you how your future bouquet will look by simply examining a packet of flower seeds.

Similarly, no good doctor should attempt to choose drugs based solely on genotype analysis. The particular sequence of DNA that an organism possesses (genotype) does not determine what bodily or behavioral form (phenotype) the organism will finally display.