Precision Medicine in the Clinic

Ultimately, precision medicine is meant to be used in prevention and treatment approaches for all health issues. At the present time, however, its day-to-day application in most disease states is relatively limited. Still, in certain areas of medicine, such as cancer care, precision medicine is already routinely put to use.

Elements of precision medicine in use today include:

• genomic testing (sometimes termed molecular or genetic testing), which seeks to identify changes in chromosomes, genes or proteins related to disease;
• targeted therapies, which are drug treatments that interfere with specific molecules (molecular targets) involved in a given disease; and
• genomic markers, which are genetic elements that convey information about an individual (such as risk for disease or likelihood to respond to a particular treatment).

Genomic testing

Genomic and technological advances have improved the ability to rapidly test biological specimens for mutations of interest, at a substantially decreased cost to the patient. Whereas the first human genome took more than 10 years to complete, commercial companies now offer testing of targetable genes with turnaround times of days to weeks. These tests are typically offered as a panel of targeted genes of interest with gene coverage ranging from analysis of hot spot regions (well-characterized mutational sites within a gene) to full gene sequencing. Protein expression analysis by immunohistochemistry or panels may also be used to monitor samples for molecular aberrations.

Despite the technical advances, genomic testing still yields a significant financial burden for the patient. Currently, few tests are covered or have limited reimbursement by Medicare or private insurance, with costs in the hundreds to thousands of dollars per test for the patient. For more information on genomic testing in clinical practice, see the section "Clinical Settings for Genomic Testing."

Targeted therapies

Targeted therapies impact specific molecules that drive a disease, such as cancer molecules that encourage angiogenesis or impact cell growth and tumor progression. Multiple targeted therapies are being developed and approved for cancer treatment. Even with the specificity, targeted therapies may inhibit more than one molecule. The majority of drugs available at this time fall into two different types of drugs:

• Monoclonal antibody: Commercially created antibodies designed to attack specific protein targets on cancer cells, or other implicated cells. Generic names of these drugs end in –mab.
• Small-molecule drugs: Chemicals that target specific molecules or pathways. Generic names of these drugs end in –ib.

Examples of targeted drugs include:

Genomics in the continuum of care

Genomic information is used throughout the continuum of care, and now markers for prevention, treatment and survivorship have been identified:

• Risk markers – to help screen patients appropriately
• Prognosis markers – to help know who is at risk of rapid progression, recurrence and outcomes based on his or her genetic makeup, not on the treatment chosen
• Predictive markers – to help guide treatment choices, including toxicity (eg, pharmacogenomics)
• Response markers – to determine response for a patient to a particular treatment

Markers for response, recurrence and toxicity impact the long-term quality of life for a patient once cancer treatment is completed. As more is learned, patients will receive more optimal treatments, targeted to their tumor, improving response and decreasing side effects by limiting exposure to drugs that are not effective and getting the best dose for them based on their pharmacogenomic profile. Thus, patients will live longer with fewer complications from their treatments (eg, neuropathies and cardiac toxicity).

Thank you for participating in this module. Click below to download the certificate.