Mis à jour : 9 sept. 2020
Image Source : Pixabay
In 2020, it is estimated that 225 800 Canadians will receive a cancer diagnosis. This disease is the first cause of mortality in Canada. However, the mortality rate has decreased since the 80s with advanced made in screening tests and treatments. Within these advances, we can find personalized medicine which aims to optimize treatment for individual patients. Organoids, microscopic organs cultivated in petri, constitute an interesting tool for this specialized approach in our battle against cancer.
Cancer, Unique for Everybody
Cancer includes hundreds of pathologies, and every single one of them are caused by an abnormal division of our cells. Its treatment is difficult because of its complexity. Heterogeneity is a part of this problem. Indeed, cells in a same tumor are not all the same, and this is true within a same patient or in comparison of different patients. Mutations appear during the evolution of cancer. This means that the first cell to cause a tumor could be completely different from the last one. Personalized medicine can contribute to a better understanding of this aspect in cancer therapy.
What is personalized medicine?
Our genetic is a perfect example of the difference residing between each and everyone of us. This explains that a unique treatment is not always efficient for all patients with the same disease. Keeping this in mind, it is not surprising that the future is looking toward personalized medicine. This approach considers genetic and epigenetic* of an individual to guide the choice of treatment. Goodbye to the one size fits all and hello precision! This could be interesting when applied to cancer using organoids.
Grow Microscopic Organs Using Patient Cells
Organoids can be growth from tumoral and healthy tissue sampled from a patient. These microscopic organs will reproduce with fidelity the genetic and structure of the organ and tumor of origin. Organoids can be used to analyze genetic modifications, and this can help to direct treatment. Then, we can use these to test treatments and their toxicity. At a larger scale, the creation of organoids biobanks represents an essential resource for fundamental cancer research.
* : murine organoids
Seeking for More Complexity
These microscopic organs are established from epithelial cells that line organs of our body. This implies that they cannot reproduce all aspects of their environment, such as tissue and other organs they could interact with. Those environmental elements are important to comprehend the entire complexity of cancer.
However, clinical trials have demonstrated some encouraging results by comparing the responds of organoids and patient to cancer therapy. In a clinical trial using colorectal and esophageal patient-derived organoids, they obtain a positive predictive value of 88% and a negative predictive value of 100%. This means that if an organoid responds to a treatment, there are nearly 9 chances out of 10 that it is really the case and on the contrary, if the organoid does not respond to the treatment, the patient will as well not respond to it. It is important to keep in mind that those statistics were realized on a small sample of 21 patients. Larger clinical trials are thus necessary to confirm those data. Will the future be organoids?
*Epigenetic: Environment-depending and reversible DNA modifications that do not change the DNA sequence. Can be transmitted between generations.