Molecular
An item on the Nature Science Update website ("Magic bullet homes in", by Philip Ball, 4 March 2002) describes work by researchers at the University of Gottingen in Germany who have developed a custom-made drug molecule that turns lethal only when it reaches cancer cells. In healthy cells it is harmless, but it targets tumor cells selectively.
According to the NSU article, the Gottingen antitumour molecule is a ring of three carbon atoms that is highly strained and apt to burst open. Open, it is a reactive molecule that wreaks havoc among the nucleic acid molecules essential for normal cell function. The drug is delivered in the form of a 'prodrug' without the strained ring but with a sugar side-group. Once the sugar is clipped off, the molecule rearranges itself into a three-atom ring, and becomes lethally active. The Gottingen team uses an enzyme to cut away the sugar group. An antibody on the enzyme ensures that the enzyme targets the tumor cells, and activates the drug molecules there.
This method is vaguely similar to another molecular ësmart bombí that employs a single radioactive actinium atom contained inside a molecular cage and attached to a monoclonal antibody that homes in on cancer cells (see Nanodot post from 16 November 2001).
March 26th, 2002 at 8:41 PM
What is a cancer cell?
These molecular smart bombs (Arguably the magic bullets dreamed of since Nixon's declaration of "The War on Cancer.") are probably much better than conventional chemotherapy but the ones described so far seem to hinge on recognition of a cancer cell.
What's to prevent the antibody from mistakenly triggering the smart bomb on a benign cell? Some forms of cancer are very hard to destinguish from normal tissue. The whole thing seems to hinge on what is cancerous versus what is not.
March 26th, 2002 at 9:11 PM
Re:What is a cancer cell?
Another thought just occurred to me. What does the rest of the surrounding tissue do with the drug? Do normal cells just take it in but don't trigger it? Do they just throw it away after a while or, do they convert into something else?
On gets the disturbing (And I hope inaccurate!) image of zillions of molecular grenades just waiting to be triggered in benign tissue–sort of a two step nerve gas. Step one implants the bomb molecules and then step two, perhaps days later, implants the enzyme that triggers the carbon ring. The person then suddenly becomes very ill.
March 27th, 2002 at 2:03 AM
Re:What is a cancer cell?
and then said person turns to slush? =] That would be freaky, but I'm sure not the case.
March 27th, 2002 at 3:04 AM
Re:What is a cancer cell?
The article addresses this at the end – "The selectivity of the damage still depends on the antibody's ability to hook onto the right cells, and on the absence of other enzymes in the body that also activate the prodrug." [emphasis mine]
Seems like both of those could be significant hurdles, but in the eyes of those with terminal cancer, an approach that might amount to Russian Roulette is likely better than nothing.
March 28th, 2002 at 7:54 AM
Re:What is a cancer cell?
Yes, despite the cautions you cite from the article this potential treatment is still far better than any conventional chemotherapy, which just steeps the body in poison in hopes of killing the right stuff.
September 3rd, 2007 at 7:33 PM
I would like an update – like are they ready to test this in humans