Pharmacogenetics has “been around since the 1950’s” but, practically speaking, is a new player in clinical diagnosis and treatment, but it is changing the way that healthcare systems, pharmaceutical companies and even small biotechs position themselves in terms of developing new ways to combat disease. With DNA sequencing dropping in price by orders of magnitude, approaches to medicine are in the process of change. Now we are able to start at the genetic level, find out your genotype for a given gene and then recommend certain drugs to you based on your personal genetic profile.
Traditionally, most pharmacogenomic profiling existed with patients needed blood thinners, specifically warfarin, where the Cytochrome P450 gene was tested to determine its presence, mutations and copy number. These features let the physician know your relative rate of metabolism to see how you will respond to the drug and what dosage you should be taking. There are a number of other cytochrome genes that are often included in pharmacogenomic tests now, such as Cytochrome P450 2C9, which is an enzyme that metabolizes coumadin.
I found two examples recently that speak to some advances made in pharmacogenetics:
The first article discusses a new diagnostic called Oncotype DX which looks at DNA of the breast cancer cells to determine if the cells are benign, malignant, or metastatic. The test is commercially available and looks at 16 tumourigenic genes to determine how the cancer is going to behave. This is the tip of the iceberg for the cancer diagnostic market. Look out for more of these test as they are bound to pop up all over the place within the next 2 years. Mark my words.
The second advance is a Nature paper from Clinical Pharmacology & Therapeutics titled Pharmacogenetics of Opioids. They are looking at a number of genes, that, when present or absent, affect a persons dosage requirements. A selection of the article abstract is seen here that speaks to what the paper’s findings indicate:
The polymorphic CYP2D6 regulates the O-demethylation of codeine and other weak opioids to more potent metabolites with poor metabolizers having reduced antinociception in some cases. Some opioids are P-glycoprotein substrates, whereas, ABCB1 genotypes inconsistently influence opioid pharmacodynamics and dosage requirements. Single-nucleotide polymorphisms in the mu opioid receptor gene are associated with increasing morphine, but not methadone dosage requirements and altered efficacy of mu opioid agonists and antagonists. As knowledge regarding the interplay between genes affecting opioid pharmacokinetics including cerebral kinetics and pharmacodynamics increases, our understanding of the role of pharmacogenomics in mediating interpatient variability in efficacy and side effects to this important class of drugs will be better informed.
The pain market is large and vast, with 100-150 million Americans (~57%) having acute and/or chronic pain within the past year. Beyond America, over 500 million cases of pain are diagnosed worldwide each year, and most patients are unsatisfied with current treatment options. The worldwide pain management market symbolizes an escalating trend, having a value of $27 billion in 2004, with an expected increase to $35 billion by 2009. The number of people affected by pain, and have access to pain treatment is likely to escalate with the “baby boomer” generation approaching older age. Also, there is a trend indicating higher incidences of cancer, arthritis, HIV as well as surgeries.
There will undoubtedly be the need for advanced pharmacogenetic testing platforms that can determine the drugs that will work best for each individual’s pain need. Be sure to see these diagnostics enter hospitals and genetic labs in a few years!
 Frost and Sullivan. (2002) U.S. Pain Management Pharmaceuticals Markets.