Pneumonochrome

This week we’ve got another cool approach to cancer: Bone marrow transplants that attack the tumor, it’s actually somewhat similar to the approach we covered last week.  Like last week, this approach uses immune cells to attack the tumors.  This time, though, doctors are taking advantage of some of what are usually considered the problems with bone marrow transplants: Graft versus Host disease.  In short, GvH is when immune cells in the bone marrow graft begin attacking the natural cells of the person receiving the graft.  The less perfect the match between the graft and the host, the more often this will occur.  Usually this means that doctors want to find as close to a perfect match as possible.

A Dr. Velardi in Italy has found that if he takes bone marrow from family members who are only a 50% match to the patient, sometimes immune cells called Natural Killer cells will attack the patient’s tumors, and they do it in a predictable way.  This is another one that’s not ready for broad usage yet, but shows potential for some really cool alternatives to the treatments we have now.

If you’re interested in the original report, it can be found here.

This week’s cool medicine isn’t really established medicine, yet.  An article in the New England Journal of Medicine details the use of a person’s own cloned immune cells in treating his cancer.  If that is a little too technical for you, BBC News reported about it, too.

Basically, this patient had very advanced skin cancer that had spread to his lungs and some lymph nodes.  The reasearchers took some blood and separated out his immune cells.  They isolated some immune cells that could identify the cancer cells by a protein they have.

These immune cells were trying to fight the cancer, but there weren’t enough of them, so the researchers caused these cells to make a lot of copies of themselves, a process called clonal expansion, and injected all of them back into the patient.

In this case, it appears to have worked, and the patient seems to be cancer free.  This technique isn’t ready for broad usage, but it is encouraging and really cool that they got it to work in this instance.  Hopefully we’ll see more progress in this area.

This week, an aspect of medicine that caught my eye was Induced Hypothermia.  The short version is that when someone has a heart attack or a stroke, part of the damage that occurs is due to that person’s cells production of chemicals that tell cells to commit suicide or do other unhealthy behaviors.  Doctors have started cooling people down, a lot, to slow down the production of those chemicals, thus reducing the damage that is caused by them.  People are studying if it helps heart attack and stroke victims, and the data we have right now seems to show us that inducing hypothermia in these patients increases survivability and reduces the severity of other damage associated with these injuries.

This week’s cool medicine is the drug Fomivirsen. Fomivirsen is an antiviral drug of a rather new sort. It’s the first antisense drug approved by the FDA. For those who aren’t sure what “antisense” means, a quick description follows. The link goes to a much lengthier discussion on Wikipedia.

Nucleic Acids are the “letters” in the genetics instructions every living thing contains about how to build itself. They can be either DNA or RNA. In this case, we’ll be talking about DNA. DNA molecules have a number of interesting properties, one of which is called complementary base-pairing. There are 4 bases that can be used to make a molecule of DNA. Each molecule uses only one of these bases. Each base is capable of binding (think of it like holding hands, of you don’t know what binding is) with one other base. The bases are represented by letters: C, G, A and T. C binds with G, and A with T. DNA is also read in a specific direction. For simplicity’s sake, we’ll just say it’s read from Start (S) to Finish (F). When two pieces of DNA bind to each other, it happens that the Start end of one piece binds to the Finish end of the other piece, so if you have a piece of DNA that reads “S-CATTCGTCACT-F”, the piece that would bind to it would read “S-AGTGACGAATG-F”. These pieces are called “complementary”. Lined up like they would be when paired with each other, they’ll look like this:

S-CATTCGTCACT-F
F-AGTGACGAATG-S

Now, when a piece of DNA is being copied, either strand of the pair can be copied to make the new piece, but when a piece of DNA is being used as instructions for making something else, only one strand is used. Let’s say the top one in the example above is the one that’s used as instructions, it’s called the “sense” strand. The “antisense” strand is its complementary strand, the bottom strand in our example.

Now to get back to Fomivirsen. Fomivirsen is a drug that is actually a piece of DNA. This piece of DNA is antisense to an important part of the DNA for the virus Fomivirsen is used to treat. What happens is that Fomivirsen pairs with that piece of DNA when it isn’t supposed to be paired with anything. This keeps it from being used as instructions for making part of the virus, and keeps the virus from growing within the person who is taking the drug.

Antisense molecules have been used for years in research labs to study what different genes do, but Fomivirsen is the first drug made of an antisense molecule approved by the FDA for use in people. It’s a new approach that could lead to the creation of drugs that are very, very specific for the bug they’re trying to kill, which will help reduce side-effects and increase potency.

Very cool. The only down-side of this drug is the way it’s given. The drug has to be injected directly into the eye of the patient, incurring an “ick-factor” almost large enough for me to have not written about it.

I think I’m going to try to start a weekly post where I briefly discuss some medical treatment that I think is neat, interesting, cool, amazing, or otherwise worth mentioning. This week, I’m going to talk about ECMO, or ExtraCorporeal Membrane Oxygenation. You’re welcome to click on through to Wikipedia to read about it there, or you can just read my short summary below.

ECMO is used in some cases where a person’s lungs aren’t working well enough for them to get enough Oxygen. It works as follows:

1. Blood is removed from a large vein in the patient’s body.
2. That blood crosses a special membrane that causes carbon dioxide to be released and oxygen to be absorbed.
3. The blood is returned to the patient’s body either through a large artery or a large vein.

This way, the patient gets the oxygen he needs, even though his lungs aren’t working well. It’s already used with newborn babies when their lungs aren’t working well, whether because of infection, underdevelopment, or trauma. You can check out the Wikipedia article if you’re curious about when the blood is returned via an artery and when it is returned via a vein.

One of the things I think is cool about it, though, is that it’s under investigation for the management of Hanta Virus Respiratory Syndrome. When a person in the US gets the Hanta Virus* it almost always causes lung problems. The person’s lungs fill up with junk, leaving no room for air to go in and out (this is a really simplified way of talking about ARDS) The standard treatment is mechanical ventilation, but that can cause injury to the lungs and isn’t as effective as it could be because the lungs are full of stuff, rather than just not moving like they should.

That’s why I think it’s so cool that they’re looking into ECMO for treatment of it. There’s no guarantee it’ll be the best approach, or any better than the current approach, but it’s a cool way of approaching the problem, I think.

*I said, “When a person in the US gets the Hanta Virus” because the strains that are more common in Europe and Asia cause a very different set of symptoms.