In Part II of this series, we are exploring the phrase “Personalized Medicine”. As written previously, the National Institutes of Health have indicated that there is overlap between the two terms. The largest gap between them lies in the understanding of what “precision” means versus “personalized” and how these are interpreted for scientific or therapeutic application.
To most, “personalized” means individualized for a single patient. This medicine model works to develop unique treatments for one single person. With this definition, there are current research endeavors focused on Chimeric Antigen Receptor T-Cell therapy (CAR-T). This is a very complex, but exciting immunotherapeutic approach that embodies personalized medicine. While some separate these two definitions, many use them interchangeably.
Personalized medicine involves enabling each patient to receive earlier diagnoses, risk assessments, optimal treatments and for development of therapeutic agents targeted to patient groups. This is essentially the definition of precision medicine. However, some approaches to personalized healthcare take it the step further, as interpreted by the definition of the word “personalized”.
With the advent of personalized medicine using an immunotherapy approach to cancer, researchers are looking for ways to utilize the patient’s own cells, to engineer them, to attack the cancer as a means to elimination of disease. Cancerous cells have developed means of evading, or overwhelming, our immune system so that it cannot complete its task of protection. Most pre-cancerous change is detected by the body in individual cells and eliminated before further advanced changes allow for growth of tumors or malignancy. When this machinery is damaged due to numerous factors, or the messages transcribed and translated from our DNA get altered due to mutations again from a multitude of possible factors, some of those pre-cancer recognitions and stop-actions disappear and cancerous proliferation ensues.
The personalized medicine approach uses a patient’s own cells to help do the work in addition to using individualized approaches with pharmaceuticals based on tumor genetic modeling. From detecting unique cancer cell markers to cellular engineering like is done with organ modeling using specific patient cells through induction to pluripotent state. Immunotherapies using a patient’s unique own autologous cells could be compared to a heat seeking missile program. In terms of seeking and destroying specific targets, the ideas are parallel. Perhaps another analogy would be a camouflaged deer hunter in the woods with a gun containing deer-tick seeking bullets created from parts unique to those specific ticks. The engineered cells are from the patient so there is no reaction or rapid destruction of these cells by an individual’s immune system. The engineered cells have special receptors embedded within their membrane that are looking for their matching puzzle piece in the unique proteins expressed on cancerous cells. Sometimes these proteins are the exact ones the cancer cell uses to evade the normal immune system. Other times, the therapy includes something that blocks tumor cell signaling so the immune system can recognize them, and the engineered cells can attack and destroy those cells.
One great advantage of this type of therapy, beyond the significantly lowered rejection risk to the patient and the lowered risk of collateral cellular damage as in with other therapeutic approaches, is the ability of these engineered cells to peruse the body and find any random cancerous cells that have made their way elsewhere but are not yet detectable as metastasis. At the cellular level, this is remarkable. Drug approaches can sometimes do this but their efficacy may be hindered by the mechanisms of absorption within the body or the pathway for drug delivery to cancerous cells. These means may not align with the location of those “floater” metastasizing cells.
Whether learning about precision medicine or personalized medicine, both are very similar and many still believe them synonymous with each other. Precision Medicine appears to be the broader umbrella with “Personalized Medicine” perhaps being a specific component under that umbrella now that we have approaches like CAR-T cell therapy. These models are not without their complexities in delivery, cost, and system-wide adoption; however, either way you may look at it, they are incredible advances in medicine that will continue to pave the way scientists and providers approach cancer therapeutics to better patient survival in all types of cancers.