You may have heard of precision medicine in the news, but what actually is it, and what could it mean for the future of healthcare?
In the past, medicine was geared for the masses and was applied to large numbers of people, on the basis of average effectiveness. If a particular substance was ineffective on 10% of the population, it could still pass through and be prescribed anyway. Before genomics, it was tricky to understand or postulate why people had such varied responses to medication, but now we have the right tools - things are changing.
While all humans have extremely similar genes in percentage terms, there are distinct differences in each of us that create our particular vulnerabilities and characteristics. We also respond differently to many treatments; a cure for one might be mediocre for another. This is particularly true for cancer. With the Precision Medicine Initiative taking off, taking into account genetics, lifestyle and environment is beginning to give us an edge - making medicine more accurate and effective.
“What’s happened in science is really breathtaking—the human genome was first sequenced in 2003, and today we can do the same thing in a matter of hours”
This emerging field can trace its origins back to the human genome project, but now sequencing is a fraction of what it once was, both in hours and cost, It's quickly becoming relatively fast and easy to read an individual's DNA profile - even if we don't understand the majority of it yet.
“I think what many people may not know is that we really have to look at our patients in the context of where the tumor came from and the entire complement of genetic and potentially non-genetic abnormalities in that cancer”
How does it differ from conventional approaches?
General approaches, especially in regards to cancer, tend to target a wider feature of the disease and focus less on specifics. Regardless of mutation and unique origin of each cancer, treatments like chemotherapy attack cell division itself - which can indeed kill many different tumours, but also causes collateral damage to healthy cells. More subtle drug treatments can target a specific mutation common to particular subsets, like breast cancer. Precision, or personalised medicine, incorporates individual profiling to establish what treatment is likely to be most effective on a patient, with minimal side effects. Because treatments often display wildly different results in individuals, precision tactics tell you which route of attack is most likely to work.
Another factor that precision medicine can improve upon is drug dosage and response. People metabolize particular drugs differently, so its therapeutic range can change from person to person. Certain genes give each of us unique enzymes which produces qualities like alcohol tolerance or the ability to digest dairy products, and genetic variation means some of us will flush out a drug faster than others. If you're dealing with a potentially harmful substance in larger doses, it really helps to know how your patient might respond - which is where precision medicine comes in.
“Let’s say we do a profile of biomarkers and genomic markers on a patient and, rather than deciding to give patients one drug, we might give them three drugs, like we do to treat AIDS and other diseases”
Because diseases like cancer can actually evolve and become drug resistant, they often contain different populations within themselves. If only one drug is being used, it might kill half but leave a remaining portion resistant to that specific molecule. Precision and accuracy gives hospitals more information; instead of shooting manically in the dark, if you know 3 different targets are present you can hit them with a cocktail of different molecules. Before treatment was a little like carpet bombing in the hope you'd wipe your enemy out, but precision medicine provides you with intelligence on what to aim at, and what to use.
'Recently doctors have started using these treatments off-label, like using a drug approved for melanoma to treat a lung tumor because they share a driver mutation, but they can’t do this with several drugs at once for fear of how they might interact in the body'
This complicated, cocktail approach is new, but it better reflects how complicated diseases can be. However, it can admittedly be challenging to apply given that drugs are tested on an individual basis rather than being part of a synergistic blend. Despite this, overcoming these hurdles could offer us unparalleled, accurate treatment - bringing us closer than ever to effective cancer cures.
Read more at PopSci