How precision medicine is changing the way we think about health care

In conversation with Dr. Shinya Ito about new advances in personalised treatment.

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Precision medicine is a promising, newly emerging approach for treating, diagnosing, and preventing diseases.

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A recent review by Dr. Shinya Ito, a U of T professor in the Department of Pharmacology and Toxicology; and Dr. Ruud Verstegen, a clinical fellow at The Hospital for Sick Children, explored the potential applications of precision medicine.

Ito wrote to The Varsity about the paper, and the applications of its findings.

What is precision medicine?

Ito explained that precision medicine is the method of “[addressing] inter-individual differences among people even within a relatively homogeneous demographic and ethnic group and in the same disease groups” to better select treatments. Precision medicine aims to empower medical staff to choose patient-specific health care approaches for higher rates of success.

In other words, precision medicine aims to identify which treatment or prevention methods will be the most effective based on the patient’s genetic and environmental background.

According to Ito and Verstegen this “offers a drastic paradigm shift” from the conventional “one-size-fits-all” approach. “There is no such thing as an ‘average’ patient in [the] real world,” Ito noted.

The science behind precision medicine

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In recent years, research has identified differences among patients with the same disease in the ways that their symptoms manifest and react to treatment. For example, similar tumours may still have major differences in their molecular make-up and behaviour.

These variations can be the result of both genetic and lifestyle factors, including diet and occupation, and may very well have an impact on how patients respond to treatment and a patient’s chance of relapse.

Despite the relative novelty of the term, certain practices of precision medicine have been implemented for years — for instance, blood transfusion patients have been matched by blood type for over a century.

The promise of precision medicine in drug therapy

Over the past decade, Ito’s team has focused extensively on pharmacogenomics — an area of medical science which Ito explained aims “to improve drug therapy by navigating drug and dose selection based on individual genetic information relevant to drug metabolism and therapeutic targets” — and its implementation in clinical settings.

Ito added that looking into the genomic profile of individual patients helps decide on choosing better drugs and doses for the patient. “For example, if we find a particular… genotype in a patient, we will not use a certain drug [in order] to avoid life-threatening toxicity (i.e., the risk is too high to accept over the therapeutic benefit).”

“If we find a particular genotype of a drug metabolizing enzyme in a patient which is known to have a functional consequence, we know that a certain drug does not work or [will be] too toxic [for] him or her.”

When asked about the limitations of precision medicine, Ito noted that it “is a work in progress,” and that “we should be careful not to overstate its value” since research into the field is constantly advancing and there are many things about the human body that are still a mystery.

However, Ito stressed the need for researchers to investigate the way genomes interact with the environment. These interactions cause differences in our bodies and can significantly affect the way that we respond to prescription drugs.