October 27, 2006

Today has been just great. It has to be from all of our prayers lining up with God’s will. That is all I can figure.

I’ve been asked several times what the difference is between chemotherapy and the Gleevec and Dasatinib. There is a definite difference and I’ll try to explain it in a couple of ways, one way for the normal people and another way for those technical geeks.

Remember that I’m a newbie to the medical scene so this is all fabricated out of what I’ve picked up in conversations with medical personnel. It is frustrating because in one sentence they are all called chemotherapy and the next sentence they are definitely referred to as different and unique to each other. Don’t worry. There will be no tests and the explanations are not guaranteed to be accurate or complete and come with no warranties implied or expressed.


CHEMOTHERAPY VS GLEEVEC AND DASATINIB – FOR NORMAL PEOPLE

Let’s say you have a sick cow and you don’t want the sickness to kill the whole herd. Using chemotherapy is like rounding up the herd into the barn, tossing in a hand grenade, closing the barn door and sorting out what lived after the explosion. Gruesome but effective if the hand grenade is closest to the sick cow.

Using Gleevec or Dasatinib is more like rounding up only the sick cow and using a small bore handgun to dispatch the sick cow.


CHEMOTHERAPY VS GLEEVEC AND DASATINIB – FOR TECHNICAL GEEKS

Chemotherapy uses cytotoxicity to perform its therapy. Cytotoxicity simply means the drug(s) are toxic to cells. Chemotherapy uses a broad brush stroke to negatively affect all cells. Through experimentation doctors have found which drugs are most toxic to which type of cancer cells.

The reason that people lose their hair, get ugly mouth sores, have stomach lining problems and skin conditions due to chemotherapy is that chemotherapy tends to affect those faster growing and dividing cells, like in hair follicles and mucus membranes. Since cancer cells are very active they are affected by the drugs also. With chemotherapy you affect (kill off) a bunch of cells and hope the cancer cells all go away before the toxicity causes permanent and catastrophic damage in too many good cells.

Gleevec and Dasatinib are called Targeted Therapy (at least for now until a better term comes up). Instead of using cytotoxicity as the method for response, they use cytogenetics. Cytogenetics is where the drug is specifically targeted to interrupt the signaling process of the cancer cells within our bodies and not use toxicity as a means of effect.

In CML leukemia the cancerous cells put out a bad protein called BCR ABL. This protein causes some DNA in normal white blood cells to change position. Gleevec and Dasatinib target the CML affected cells and stop them from emitting the BCR ABL protein. Lowering that BCR ABL protein level in the bone marrow stops the swapping of DNA in more normal white blood cells.

The problem with narrowly focused targeted drugs is that cancer cells are pretty smart. In order to survive they mutate out past the effectiveness of the drug until they become resistant to the drug. That is why Dasatinib was produced to help those of us whose cancer cells have successfully mutated past the effectiveness of Gleevec’s range. Targeted therapies are definitely much safer and less damaging to our normal body cells.