I recently read an article about the potential use of nanodiamonds in the treatment of certain cancers, published in Science Translational Medicine (link). Before getting into the diamonds themselves, a little background into why they are needed in the first place is necessary.
All things considered, the body is typically very good at getting rid of toxins. Our world is surrounded by all sorts of things which could be considered toxic, but the typical healthy person is usually unaffected. This is thanks in part to certain proteins in the body that cells use to pump toxins out. In a healthy person, this is certainly a useful function. If the toxins are allowed to remain in cells, then they are permitted to run their course, doing damage on the cellular level. Ultimately this can lead to things like cell death or cancer.
Such toxin removing pumps seem to be a good thing. However, consider now a chemotheraputic drug, a drug intended to treat cancer. Such drugs are usually themselves toxic. In fact, most chemotheraputic drugs work because they are disproportionally toxic to cancer cells as opposed to body cells. Unlike the majority of antibiotics which specifically target bacteria, chemotheraputic drugs tend to be more general. This is why there are often so many negative side effects of chemotheraputic drugs: normal body cells are killed along with cancer cells, but cancer cells are killed far more frequently than body cells.
With that in mind, consider a cancer cell exposed to a chemotheraputic drug. This is a toxin that threatens to destroy the cell. Obviously, it is in the cell's best interest to get rid of such a toxin before it can run its course. If the cell is equipped with pumps for getting rid of toxins, then suddenly this seemingly life-saving device becomes a means through which cancer can proliferate. The cancer cells pump out the drug, preventing damage to themselves while still damaging surrounding healthy tissue.
At this point, the cancer cells have become drug resistant. Worse yet, it's possible for the same pump to get rid of multiple different chemotheraputic drugs. In other words, if the cancer has built up a tolerance for drug X, then there is a significant chance that it has built up a tolerance to drugs Y and Z, as well. In the real world, this is an all to common occurrence; the paper cites that this occurs in more than 90% of treatment failures of metastatic cancers.
Ultimately, the problem isn't that the drug has lost effectiveness, but that the cancer is able to get rid of the drug before it can do any significant damage. If there was a way to bypass the pumps and force the drug to stay alongside the cancer, then the treatment would still be effective.
This is where the nanodiamonds come in. Through a specific process, one can attach chemotheraputic drugs to nanodiamonds, and then inject the coated diamonds into patients. Though the diamonds are small, they are large enough to become lodged in tissue for several days at a time. While the coated diamonds are in tissues, they constantly expose the given tissue to the drug. Simply pumping the drug out is not possible, as the drug is physically forcibly in the tissue thanks to the diamond.
Although it may sound dangerous to have such diamonds in the body, the authors of the paper found no negative side effects of diamonds alone. They left the body typically within 10 days, with the vast majority of them leaving in under seven days. The body showed no active immune response in trying to get rid of the diamonds, nor did it show any attempts to break down the diamonds. It was almost as if the body didn't detect they were there, and they didn't seem to cause any harm on their own.
Using a certain chemotheraptic drug, they ran a series of trials on mice. They found that the drug alone is more effective than the drug bound to the diamonds on cancers that are not drug resistant. Given that the entire point of the diamonds is to provide a mean to treat drug-resistant cancers, this isn't particularly important treatment-wise. What is important is that the drug with the diamonds was far more effective than just the drug on resistant cancers. In fact, for one group of mice with drug-resistant cancers, the effective dose of the drug without the diamonds was sufficient to kill the mice. With the diamonds, they could give an effective dose at levels which were far less harmful to the mice, to the point where mice didn't die from the treatment but were still being treated effectively.
To me, the diamonds seem to have a lot of potential, though there is a long way to go. The paper notes that people have been trying all sorts of similar delivery systems of chemotheraputic drugs to drug resistant cancers with limited success. Usually the delivery system itself is toxic, though in the case of nanodiamonds it tentatively looks safe. However, there is still a long way to go. I would have liked to see more indicators that the diamonds were nontoxic. Additionally, a trial on humans is necessary before we can actually know if this would be effective or not in the real world. That said, things sound hopeful.
