Thursday, September 10, 2009

Purpose in a bubble

Yesterday, I met with a researcher that was working on lipoproteins in neuroblastoma. The idea is really simple enough. Lipoproteins are essentially tiny little fat bubbles that can be used to carry chemotherapy to tumors. Why do we care, you ask? Well, part of the problem that we all have in treating neuroblastoma (any cancer really) is the issue of toxicity. In fact, in most cases, toxicity is the factor that limits the amount of tumor we can kill and the amount of treatment our children can receive. You see, every time chemotherapy is given it has a very long journey to actually kill the neuroblastoma. It has to make it out of the bag, down the IV line, into the vein, through the body, and finally to the tumor. Sometimes, the chemotherapy even has to be metabolized by the liver before it becomes useful. The problem is that chemotherapy is not particular smart. It can effect everything it passes through. It can affect the heart, the liver, or just about anything in the body it passes. In fact, many of them can even hurt you on the way out as they are filtered by the kidneys. This is a major factor in most drugs that our children receive for treatment. We are only able to get so much of the potentially life saving drug because of the very real fear that any more would drug create significant damage to their little organs.

What if you could take all of these chemotherapies and put them in a bubble? What if this bubble could make it out of the bag, down the IV line, into a vein, and throughout the body without effecting a single organ? What if these bubbles had little magnets that could actually seek out tumors? What if it was the tumor that was the only thing that could pop the bubble and release the drug?

If this was the case we, would be able to spare a tremendous amount of toxicity. It is likely that we could even significantly increase the dose of drug given, increasing its efficacy. Just as importantly, we would be able to reduce, if not almost entirely obliterate, toxicity. That means no hearing loss with cisplatin and no heart damage with doxorubicin. Potentially, this could also mean less hematological toxicity leading to fewer transfusions, infections, and risks.

There are actually several versions of liposomes and lipoproteins in trial today. There is even a formulation with irinotecan that had great responses in adults which we have been trying to get into neuroblastoma for some time. There are several being tested with paclitaxel in adults and even a few with cisplatin. There is no doubt that this "bubble" technology is on its way.

While understanding the concept is pretty simple, actually doing it is quite another. It is no easy feat and it was this meeting that was on this very subject. Getting the drug into the bubble for the most part is pretty easy. That has been mastered with many lipophilic drug (drugs that dissolve in fat) The trick is keeping the bubble stable as it makes its journey, helping it find its target, and ensuring the tumor has the ability to pop the bubble. It was these topics in the framework of neuroblastoma that we discussed yesterday.

It was an interesting lunch and I think we both came out with some new ideas on how we could borrow from some of the successes seen with these types of drugs in other cancers and manipulate them to work well for children with neuroblastoma. The good news is that the technology is there. This can be done. The struggle will be in coming up with the funds to get research like this moved forward. I truly believe it to be a very large part of the future of chemotherapy.

It is another example of purpose in a bubble.

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