Thursday, April 30, 2009

Why aren’t new therapies for treating swine flu (and other diseases?) available?

Nano Chem Report
Blogging on nanomedicine, dendrimers and nanolaw since January 2009

A few years ago, I had the pleasure of meeting Anil Diwan, the founder of Nanoviricides at a conference. He’d developed some interesting technology for drug delivery and had formed a company to commercialize it: Nanoviricides ( I found the technology compelling enough to even buy some stock in the company, but the commercialization process is clearly long and hard.

What they’ve developed is termed a nanoviricide, which consists of two components. The first component is a ligand designed to bind specifically to a target surface. These ligands can be altered to bind to a variety of different viruses. The second component is a polymer nanoparticle. Once the ligand binds to the virus, the polymer then flows around the virus. This effectively “slimes” the virus, and inactivates it. The energetics of causing the polymer to flow around the virus are probably driven by entropy, but I’m not sure it’s been well studied/modeled. The advantage of this technology over a lot of competing technologies is that the ligand has to only bind to the virus- the actual binding site isn’t that critical. In contrast, most drugs designed to interfere with viruses do so by blocking the entry of the virus into a cell or by attacking the virus in a specific fashion – such as replication. Most AIDS drugs work this way. Unfortunately, these drugs can fail because the virus uses a variety of ways to gain entry into a cell- hence the need for things like an AIDS cocktail. What this means is that it’s not enough for most drugs to just bind to the surface of the virus- they have to get to the right spot on the virus to be effective. Nanoviricides compound is different since the purpose of the ligand is merely to recognize a virus and bind to it- the polymer does the rest. It’s a much more tractable problem.

Why would it be nice to have such a drug to be widely available? Well, the vaccine approach has proven to be very effective at controlling many of the infectious diseases that used to take an enormous toll on human life such as smallpox, polio, rubella, etc. Unfortunately, there are some diseases such as AIDS where it’s been very hard to develop a vaccine, even after decades of effort. The other problem is that vaccines generally don’t do a lot if you’ve already been infected with the disease. Once you’ve been infected, generally the infection has to run its course.

Most therapeutic approaches utilize the body’s immune system in some fashion. The nanoviricide is actually a very different approach since it really operates largely independently of normal immune processes by providing an additional way to inactivate viruses. Even people with compromised immune systems should be able to tolerate a nanoviricide, and once a virus has been “slimed” it’s eventually recognized as a foreign body and excreted.

A nanoviricide for swine flu would be pretty useful about now. It would be a good second line of defense for people who weren’t vaccinated for whatever reason. Some vaccines are not well tolerated in the general population and it may not be practical to vaccinate the entire population. If there would be a reasonable alternative therapy to a vaccine, the risks of not being vaccinated are much more acceptable. While a nanoviricide would not confer long lasting immunity from the disease, since the outbreaks of swine flu are so rare, this may not be a significant drawback. It would certainly reduce the mortality of the disease and likely lower the costs of treatment by shortening the time course of the illness and the amount of supportive care necessary.

It’s generally government entities that purchase vaccines, but this process has been a troubled endeavor as of late. While it’s clear that the Obama administration has lots on its plate right now, a better treatment for people who do get infected with swine flu would certainly reduce some public anxiety. It’s probably too late to manufacture a nanoviricide in quantity to have an effect on this outbreak of swine flu, but it should be possible to have something in hand for the next one.

Sam Brauer

Nanotech Plus, LLC

Stamford, CT USA

(203) 968-8899