Precision Medicine for a 21st Century World
Current trends in healthcare are accounting for the realization that an individual’s disease is inherently personal, affected by the patient’s genetic makeup. As such, medicine is evolving towards medical professionals who are able to use more precise and defined technological tools for each individual patient, ushering in the concept of personalized, or precision, medicine. Personalized medicine involves analyzing an individual’s genetic profile to qualify a presumed diagnosis, to group patients for more tailored therapy, and to develop and translate treatments with greater benefits than risk into a clinical setting.
Disease starts with the cells of the human body. All the cells of the human body (except red blood cells) contain DNA, which is considered the instructions for life. Strikingly, the genetic information contained in all these cells is identical; however, the expression of the genes differs between cells. Expression refers to which genes are used by the cell, and accordingly what proteins are made. Proteins are the main effectors of the cell, doing most of the work within our bodies. Here is where personalized medicine steps in. Based on the genomic and proteomic (protein) aspects of an individual’s profile, person A may be diagnosed with the same disease as person B, but the two may respond differently to their prescribed drugs. Studies have shown that some drugs work for a percentage of patients, while other patients may have a reaction or simply not respond in the desired way. Genome-wide association studies, which involve correlating genomic profiles with traits, or in this case diseases, will be useful in providing information for how to best identify the medical problem occurring in the individuals, and then possibly how to treat them.
It is expected that in the future, personal medicine will become much more widely adopted. A simple tissue or blood sample could be taken, and the DNA or mRNA (DNA to protein intermediate) could be extracted. From the data retrieved, doctors can analyze whether a person is more likely to get a disease, what treatment will best target the patient’s disease, or how the treatment is working for the individual undergoing therapy. Furthermore, the implementation of electronic medical records may allow researchers to find more associations between an outward presentation of disease and a genetic alteration by combining analysis of findings from the clinic with findings from the blood sample. The promise for prevention is additionally promising. Since blood circulates throughout the body, it carries proteins from the body’s tissues. Frequent assessment of the blood for certain proteins over the long term can send up a red flag for better prevention strategies or early treatment if levels are creeping towards abnormal or have suddenly altered.
For results that command greater significance, scientists must develop a better understanding of how certain proteins and sequences of DNA affect expression of different genes and cell behavior. There should not only be an understanding of what DNA or protein marker is related to disease onset or intensity, but also how that marker is affecting disease progression. Select markers that meet both these criteria can be of substantial use for clinicians, allowing them to both diagnose and treat individuals if a targeted therapy is available. In order for these studies to be conducted, large pools of DNA are often required, thus highlighting one of the other major roadblocks to implementation: population size. Recruiting patients and healthy individuals to help further genomic research for possible clinical application can be difficult. Individuals participating in scientific studies must fully understand the future implications of their genomes being sequenced and analyzed, and often this rides on the effective communication between the scientists, clinicians, and the public.
Whereas relevance for application and the level of participation remain two challenges for a more extensive utilization of the personalized medicine approach, financing is pushing the model further into realization. Developed sequencing technologies have allowed for a greater number of longer DNA segments to be sequenced at a much lower cost than just 10 years ago. Moreover, the National Institutes of Health (NIH) is channeling greater amounts of money into projects that demonstrate relevance to personalized medicine. The Human Genome Project, which was started in 1990, and completed 13 years later, was one such project that the NIH partially funded, producing results which have helped guide genomic research.
While widespread application of personalized medicine will take some time, there are quite a few targeted approaches being pursued in current patient treatments. A notable example comes from the world of leukemia. Subsets of leukemia patients have been found to have mutations in their genetic composition which results in a distinct protein being expressed by their cancerous cells. This protein is known as the BCR-ABL kinase, and currently drugs known as tyrosine kinase inhibitors can be used to target the leukemic protein in these specific patients’ cells (however, due to the nature of cancer, in some cases the leukemic cells can become resistant to the drugs over time). In essence, this allows oncologists to identify a group of patients with the so-called “Philadelphia chromosome” genomic profile for a more specific treatment.
While personalized medicine holds exciting promise for the near future, the field is in its infancy with maturity riding on scientific discovery and effective clinical translation.
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