An article in The Times reports that cancer patients in the UK will be given personalized treatments.
A pioneering approach to personalised cancer care where therapy is genetically tailored to individuals’ tumours is to be offered to NHS patients for the first time. Up to 6,000 cancer patients a year will have their tumours analysed for a wide range of genetic defects that can help doctors to choose the most effective therapy in an initiative that promises to transform the way the disease is treated . . . It will involve classifying individuals’ cancers according to the genetic mutations that drive them, rather than their position in the body. Smart drugs that target these mutations can be selected so that patients get the treatment that is most likely to work for them . . . Harpal Kumar, chief executive of the charity, said: “We believe that cancer medicine has reached a point where increasingly the genetic characteristics of individuals’ tumours will and should dictate what treatments they receive. We now have enough genetic markers and drugs for this to make a real difference. It’s patently obvious that this is going to be the way of the future. In the long term, once the benefits are proven, the NHS should be doing this.” In the past few years about two dozen targeted cancer drugs that attack specific genetic mutations have been developed, such as Herceptin for breast cancers with defective HER2 genes. They are effective, however, only when a certain mutation is present, so tumours must be tested first.
The notion of personalized medicine dates back to the 1950s. Willyard:
It was in the 1950s that scientists found the first evidence that people’s genetic makeup can alter their response to drugs. Alf Alving at the University of Chicago had observed during the Korean War that black soldiers were more likely than white soldiers to develop debilitating anemia when given antimalarials such as primaquine. In 1956 he found the cause: an enzyme deficiency—the result of a rare allele on the X chromosome—that leaves red blood cells vulnerable to oxidative damage and causes them to burst. Based in part on this work, German geneticist Friedrich Vogel coined the term ‘pharmacogenetics’ in 1959 to describe the role of genetics in drug response. (Willyard 2007)
Pharmacogenetic investigations aim to identify complex patterns of gene variation in an attempt to correlate these patterns to different drug response genotypes. Differences between groups of people exist not merely with respect to the metabolism of xenobiotics, but also with respect to patterns of disease. For example, black women with certain breast cancers have a higher incidence of developing metastatic cancer than their white counterparts even when the same treatments are given. Further, black women under 50 years account for 31% of breast cancer while white women under 50 account for only 21%. The incidence of breast cancer that is estrogen receptor-negative also varies with black women having an incidence of around 40% and white women 23%. Triple-negative- tumors—negative for estrogen receptors, progesterone receptors, and human epidermal growth factor receptor-2 tend to spread quickly and are far more common in young black women (Couzin 2007). Incidence of diseases vary between the sexes. Males experience more schizophrenia while women experience more depression, anxiety and eating disorders (Holden 2005). Myocardial infarction (MI) differs between sexes with MI occurring much later in women than men. Women have greater risk from MI if they suffer from diabetes and high blood pressure, but heart failure and sudden death are less frequent women. Women experience less typical angina but MI are more likely to be lethal. Left ventricular hypertrophy occurs later in women but is associated with greater risk. (p234-5)
Humans react differently to drugs and disease. If scientists study humans and human tissue, more of these differences will be discovered and patients will benefit. If society funds mouse models of cancer we will find more cures for cancer in mice.
Couzin, J. 2007. Human genetics. In Asians and whites, gene expression varies by race. Science 315 (5809):173-4.
Holden, C. 2005. Sex and the suffering brain. Science 308 (5728):1574.
Willyard, C. 2007. Blue's clues. Nat Med 13 (11):1272-3.