I am the drug
In the runner-up article for the Max Perutz Science Writing Award 2012, Ketan Shah gives us an unconventional description of his work helping to develop new radioactive drugs for use in the scanning and treatment of cancer.
I am the drug and there is a sting in my tail. I have gone by many names as I have developed, but my most user-friendly is Indium-EGF. I want to show the world that I am special.
They are trying not to put too much pressure on me, but I know they are excited as they get me ready to go into a person for the first time, hopefully in 2012. They are supposed to be detached and scientific; they are not supposed to be excited. But I know they are.
I come in two parts, stuck together in a clever way. My head is called EGF, and my tail Indium-111. EGF stands for epidermal growth factor. The human body can make EGF but I was made in a test-tube. I’m their test-tube baby. Some cells — some of the tiny building blocks of the body — have what are called receptors for me: EGF receptors. These sit on the cells and are particularly sticky only for EGF. So when I’m injected into the body, rushing around in the blood, oozing into all parts of the person I’m in, my head sticks onto the cells with lots of EGF receptors.
Sometimes cells that go wrong and turn into cancer have too many EGF receptors. Cancer is definitely not user-friendly. But cancers can be checked to see if they have lots of EGF receptors. You’ll see where I’m going now – I’ve been designed to treat people with just those cancers. I’ll be no good for other people with cancer (whose cells do not have the receptors), so there’s no use wasting time and money giving me to those people. I’m special because I’m personalised.
So what do I do when I get there, sticking to the cancer? Remember my Indium-111 tail? Well, Indium-111 is radioactive! I told you there was a sting in my tail. Radioactivity sounds dangerous, and it is, but the trick with using radiation as a treatment (what they call radiotherapy) is to target it to the cancer while avoiding as much of the normal body as possible. Radiotherapy machines physically point radiation at the cancer, and they do it pretty accurately. I’m different because I am injected into the bloodstream, and it is the EGF that makes sure I get to the right place and I stay there. I’m special because I’m targeted.
EGF receptors are really useful because they actually pull me into the cancer cell so my radioactive sting can work. Indium-111 only destroys things very close to it, so I get it right next to the cancer cell’s DNA to kill the cell. They’ve spent years putting me with cancer cells in test-tubes, watching me go into the cells and kill them. I can see why they are excited. I’m special because I’m deadly to cancer cells.
Another great thing about Indium-111 is that you can see it on special body scans called SPECT scans. So after I’m injected into people with cancer, SPECT scans will be done to make sure I’m in the right place. It is amazing to think that when I’m in there, sticking to the cancer, someone can actually watch me. I’m special because you can see where I am.
It seems so simple, I can hardly wait to get started. But I’m not so simple. Being radioactive, everyone has to be careful with me. That goes for the people who make me, the staff on the wards, the person I’m going into and their friends and relatives. It means a lot of planning and measuring before my first try-out, my clinical trial. I never forget that the scientists who thought of me have had to be careful ever since they put me together.
The most important thing about my first trial is not whether I work, but whether I’m safe enough to use. That may seem odd, but it doesn’t matter how deadly I am to cancer if I’m deadly to everything else too.
So in I’ll go, into the blood, zipping round until I stick. My radioactive tail will be glowing on the SPECT scan, more like a firefly than a bee, and I’ll stick to the EGF receptors on the cancer. I’ll go into the cancer cells, and attack them with my sting. I am special. I am Indium-EGF. I am the drug. And there is a sting in my tail.
Ketan is a clinical oncologist who has just finished an MRC Clinical Research Fellowship at the University of Oxford’s Gray Institute for Radiation Oncology and Biology.