These days, if you read any news article about human health, the words “personalized medicine” likely appear somewhere in the story.
What is personalized medicine? Is it really that revolutionary? How can personalized medicine be useful to veterinary medicine?
Personalized medicine is defined according to Wikipedia as “a medical model that proposes the customization of healthcare – with medical decisions, practices, and/or products being tailored to the individual patient.” This approach often entails the use of specialized diagnostic tests-often employing genomics, proteomics, or other –omics to help guide the clinician. The results of these tests can lead to a more accurate diagnosis, help the medical professional determine the underlying genetic or molecular basis for the disease, and ultimately tailor the therapy based upon these results.
Hasn’t medicine always been personal?
To some extent, doctors and veterinarians always personalize the medical care they deliver. We treat Chihuahuas differently than Great Danes, we treat sight hounds differently than bulldogs, and Greyhounds differently than Rottweilers. Personalized medicine takes this level of customization to a completely different level. For example, instead of just changing a dose based upon your patient’s weight or breed, imagine a veterinarian prescribing a different medication based upon a pet’s gene expression. Genes regulate metabolism, determine a pet’s susceptibility to cancer and by what mechanism that cancer grows, as well as affecting how a pet will react to chemotherapy.
Personalized medicine and veterinary oncology.
With the publishing of the canine genome, veterinary medicine has truly entered the genomic age. In veterinary oncology, the traditional way to diagnose and categorize malignancies was by evaluating their histology. This information along with staging tests such as radiographs, ultrasounds, bone marrow aspirates, lymph node evaluation among others, allowed as to assign a clinical stage and a grade to most malignancies. We are on the verge of changing this paradigm, categorizing cancers by their genetic signature. To some extent we have already “personalized” therapy for dogs with mast cell tumors. We routinely recommend evaluating mast cell tumors for the presence of a c-kit mutation. This information does influence how we treat that patient.
Although the number of genes and therefore the number of potential mutations is exceedingly large, there is evidence to suggest that cancer-causing mutations affect only 12 basic cellular pathways (http://www.sciencedirect.com/science/article/pii/S1090023315000088). This information may allow therapies to be personalized based upon which pathway(s) are altered rather than on the more onerous task of basing therapy on the genetic variations of each tumor.
Veterinary oncology is rapidly moving into the genomic era. We still need to genetically characterize most of the common cancers that affect both dogs and cats, but I am incredibly excited about the prospect of making therapeutic recommendations based upon the genetic signature of a patient’s tumor. When this change occurred for lung cancer in people, survival times dramatically improved (http://126.96.36.199/biochem/biochem230/papers2005/week5/2129.pdf) and I am hopeful that this will happen for our patients as well.