When a patient presents with cancer today, physicians should take a sample of the cancer cells, sequence the genes, and look for known mutations. Once that is done the best drug can be chosen to target only the cells with that mutation resulting in significantly less side effects than the old chemotherapy drug approaches given their targeted nature. One of the challenges we now have is that not that many mutations have been identified yet compared with the number of cancer mutation types that exist. So we have around 50 identified now but there are potentially hundreds more yet to be discovered. And out of those 50, we don’t have drugs for them all yet.
It is interesting to note that one can have the same gene mutations in cancers in different parts of the so it appeared that the body part that the cancer was found in was irrelevant.
So far so good.
The story now takes another twist.
Some clinical trials conducted recently by National Cancer Institute and Memorial Sloan Kettering Cancer Center have tested treatments on the same cancer mutation in different body parts. These trials found drugs to be more effective if the cancer shared the same gene mutation, as well as body part.
What we don’t know now is why some drugs work in some patients with the same gene mutation and the same body part but not in others sharing these. Other non-cancerous genes (and possibly non-genetic factors) are clearly also at play. The planned next step will be combining multiple targeted treatments in a cocktail (similar to HIV treatments) specific to that individuals make up.
Of course on top of these scientific challenges, we also have others such as cost of sequencing, insurance coverage ,and education (both patient and physician).
So precision medicine has come a long way but we still have some way to go before we crack the cancer code fully and treat all patients successfully.
“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,” says Razelle Kurzrock, the director of the Center for Personalized Cancer Therapy at the Moores Cancer Center at the University of California, San Diego. Since researchers can read the genes more effectively than ever before, treatments that target the mutations have suddenly become a reality.