What is personalized medicine?

A consistent theme that has been hammered into our heads throughout this Molecules to Medicine block is how personalized medicine is the future of medicine. By and large, the current approach to medicine is "one size fits all," which the professors always utter with a negative voice inflection so we medical students are sure to know that this is a bad thing. Personalized medicine, in contrast uses genetic or molecular analysis in order to predict who might respond well to a given therapy over another.

The most well known example of such personalized is in breast cancer. A quarter of all breast cancers are characterized as being caused by a mutation in HER2, human epidermal growth factor receptor (EGFR), which becomes overactive when it's mutated. This EGFR, as its name implies, normally activates signaling cascades that control cell adhesion, migration, and proliferation, cellular processes that are all important in the generation of a tumor. A HER2 mutation thus causes a particularly nasty type of breast cancer, but a drug called Herceptin has been developed that calms down the overactive EGFR by binding to and inactivating it. As you might expect, only patients who are positive for this HER2 mutation will benefit from Herceptin treatment.

Several weeks ago, we learned about Li-Fraumeni syndrome, which is a disease of increased susceptibility to developing cancer at an early age caused by mutation of a particular protein called p53 that is responsible for "proofreading" the genome as each cell is being replicated and fixing any mistakes. If this genome housekeeper gene is mutated, it's all of a sudden much easier to accumulate more and more mutations until, by chance, you get a cell that divides like crazy (in complete disregard of environmental signaling) and acquires other characteristics of a cancerous cell. So, radiation treatment is probably not such a good idea for patients who have a mutation in p53, because the radiation will likely just cause more mutation events that their dysfunctional housekeeping protein p53 is unable to fix.

During this morning's lung cancer clinical vignette, the lecturer again drove home the idea of personalized medicine by showing how one type of lung cancer is responsive to drug A while another type of lung cancer is unresponsive to drug A but more responsive to drug B. A molecular characterization of the exact kind of lung cancer starts to look like a necessary first step before deciding on any therapeutic intervention.

Indeed, for some diseases such as lung cancer, or when a patient's family history is highly suggestive of a mutation in one of those genome housekeeping genes, the standard of care is already trending toward a personalized approach to devising a treatment plan.

First Molecules to Medicine test

The first Molecules to Medicine test is tomorrow. I'm not nearly as scared about it as I was going into my first Human Body test, but that has both its upsides and downsides.

Pro: I'm no longer a Scary Medical Student whose temporary best friend is his cadaver and who has to take vitamin D supplements because he studies 16 hours a day and doesn't get any sunlight because of it. In fact, I now have meaningful non-medical-school-related conversations with my family/friends, I've renewed my Netflix account, and I've even gone out a few times. (Okay, I've gone out once since anatomy ended. After the last exam.)

Con: Motivation is a problem. Whereas all the anatomy material was brand new to me, I've had a lot of molecular and cellular biology before, both in undergrad and graduate school. That's not to say that this block will be a cake walk, by any means, just that my mind is primed to re-learn a good portion of this material and to place new information within a pre-existing framework of knowledge. But, it also means that I have to guard against boredom and procrastination.


The material being covered in this first test includes: bioenergetics, DNA structure, DNA replication, DNA repair, DNA transcription (process of converting DNA to RNA), RNA structure and post-transcriptional processing, gene expression, amino acids and proteins, translation (process of converting RNA to protein), the cell cycle, and various tools of molecular biology.

Also, one of the highlights of Molecules to Medicine so far has been clinical vignettes. These are lectures of specific diseases that tie into relevant material being covered in other lectures. For instance, we learned about prion disease after a lecture on protein folding. We are also responsible for knowing the molecular biology of Alzheimer's disease and Li-Fraumeni syndrome for tomorrow's test.


N.B. Yes, writing this post was indeed an exercise of procrastination. Back to studying.

A real change of pace

This transition from the Human Body block to the Molecules to Medicine block is a real change of pace. I actually spent the entire weekend relaxing and not studying! A large part of why I feel comfortable doing this is that I've already had a lot of the biochemistry and molecular biology material - it's not all new to me. Also, biochemistry is much more conceptual than the rote memorization of anatomy, which I think plays better to my learning style. Some second-years told me that after Molecules to Medicine the coursework returns to its previous memorize-as-much-as-you-can modus operandi.

So, I'll enjoy my luxuries while I can.