macular degeneration, macular, diagnosis Thank a Mouse – My Macular Degeneration Journey/Journal

Thank a Mouse

This page is just me being inquisitive. If you are not up for me trying to figure out biochemistry, you might want to skip this page.

Looking at the medications they are using for wet AMD and the new treatment for dry AMD, lampalizumab, I noticed something.  Most of the generic names end in -zumab. What the hey? What is that????

To begin with, I discovered there are two suffixes, -ximab and -zumab.  Wikipedia actually has a whole list of medical suffixes but I am concerned about two right now. Those are the ones related to drugs for AMD. Suffice it to know that every suffix means something.  -olol for example will always mean a beta blocker. Of the two I am interested in: – ximab always stands for a chimeric agent that responds to more than one antigen;  and -zumab always stands for a humanized antibody.

See what I mean about just skipping this page?

Chimeric.  Now I knew what a chimera is. A chimera is a single organism composed of cells that should have made up multiple organisms. The organism  is made of genetically different cells. According to MedicineNet human chimeras were discovered when it was noted some people have two different blood types. The generally accepted ways a human chimera is formed are for nonidentical twins to share blood in utero or for one to absorb the other.

Once again according to Wikipedia, chimera proteins are produced through the joining of two or more genes that originally coded for two different proteins. The properties of the new derive from each of its ‘parents’. Naturally occurring chimera are often found in cancer cells; thus, it would appear, the wisdom of using manufactured chimera proteins to battle cancer (a genetic version of fighting fire with fire). Chimeric cancer cells happen because of random genetic mutation. Chimeric proteins in drugs happen by design. Read genetic engineering.

Forging ahead here, every drug ending in -zumab is a ‘humanized protein’. And, no, that does not mean it is kinder and gentler. It means that the base protein used in the drug probably came from a mouse. Generations of lab mice have had the very stuff of their being manipulated in the search for ways to improve our health. Think kinder thoughts about the little devils.

Because – actually two becauses – there are a lot of similarities between mouse DNA and human DNA, we can use mouse as the frame for our designer drugs. Because some of their proteins are foreign to us and would cause an allergic reaction, the proteins have to be ‘humanized’. Potentially offending sequences are cut out and replaced by sequences found in humans.

The idea is to produce proteins that will get into a sequence of reactions and somehow change it. In dry AMD lampalizumab weakens the immune reaction. Wet AMD drugs intercept the SOS message being sent by the eye. That is the one saying the eye needs more ‘supplies’ and new ‘supply routes’ (blood vessels) should be built.

So that is the answer to that burning question (you really were dying to know; I know). If you are taking a drug ending in -ximab or -zumab,  you are the beneficiary of altered protein sequences. Be grateful. Thank a mouse.

written July 1st, 2017

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