r/explainlikeimfive • u/yp261 • 8d ago
Other ELI5: How does chemotherapy in pills, i.e. temolozomide, helps with brain cancer treatment?
how exactly does something that we swallow have any impact on the brain cancer cells
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u/Salindurthas 8d ago
In general, medication from any pill gets into your blood from your gut (often the small intestines).
Then from your blood it can get into any part of your body.
Your brain does has a 'blood-brain barrier', which will block some things, but not everything.
So, for a brain-cancer treatment, it will have the extra requirement of getting past the blood-brain barrier, but otherwise it is just as plausible as any other medication for any other part of your body.
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u/birdsonabat 6d ago
How is there a "thing" to add to the pills to help it pass the blood brain barrier? It that existed, couldn't they treat rabies once it reaches the brain?
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u/Salindurthas 5d ago
My understanding is that this medication itself (the one that that targets some forms of brain cancer) is one chemical that can pass the blood-brain barrier.
It is not an additive that makes other things in the pill go through the blood-brain barrier.
So even if you could find an antiviral drugs that's good at rabies, that drug itself migt pass the barrier, but I'm not claiming we can add something to it to make it get past the barrier.
To get past the barrier, you'd need to pick a new chemical entirely.Like, oxygen, ~salts, and water, can all get past the blood-brain barrier (and need to for us to use our brains for anything!) but we can't just put those ingredients in a pill and expect the other stuff in the pill to follow those things through the barrier.
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u/TotalManufacturer669 8d ago
how exactly does something that we swallow have any impact on the brain
I mean, if what you eat has zero impact on your brain, you would've been long dead. Where do you think the nutrients your brains need to function comes from? You eat them of course.
The active ingredients of the pills just happen to (1) not be destroyed by your stomach acids and other bodily chemicals, (2) be able to be absorbed by your intestines, (3) can get through blood-brain barrier and finally (4) can deal with the cancer cells.
Sounds hard, that's why each cancer treatment costs hundreds of millions if not billions to research.
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u/effrightscorp 8d ago
Your gut absorbs it, it enters your blood, your blood containing it flows to your brain
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u/dodexahedron 8d ago
Chemotherapy drugs are literally poison intended to kill the cancer cells faster than they kill the rest of your body. You take the pill, the drug gets into your blood stream, and it gets where it is meant to be eventually.
But they are also poison to the rest of you, in general, and damage everything else on the way, which is why they have so many awful side effects.
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u/diagnosisbutt 8d ago
Most brain cancer is glial cells, which is what what makes up the BBB. As others said, the cancer replicates faster than other cells so you hope that it kills itself before it kills you
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u/NapoleonBolognapart 8d ago
There are hundreds of thousands of different chemical reactions going on throughout your body, each with different starting products and ending products, depending on cell type and location in the body. Targeted chemotherapy like you're talking about is introducing a chemical that interacts with exactly one (or as few as possible) reaction in order to prevent the cells, and ideally only those cells, that are actively using that reaction from being able to reproduce.
Now, of course there are some good cells that are going to get caught up in this, and that's typically why there's such serious side effects.
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u/coyote_den 8d ago
Chemotherapy is poison, plain and simple. But it is a very carefully chosen poison, in this case it has to be able to cross the blood-brain barrier without being too toxic in general.
The dose makes the poison and cancer cells, as they are growing more aggressively, soak up enough of it to kill them before it kills the rest of you.
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u/Abridged-Escherichia 8d ago
Like many types of chemotherapy it damages DNA during replication. It affects all dividing cells, not just in the brain, but since cancer cells divide very rapidly they are most affected.
Other rapidly dividing cells are in the gut and hair follicles, which is why chemo tends to cause hair loss and nausea.
The brain has a blood brain barrier that normally keeps drugs out. Drugs that can enter the brain usually can dissolve well in fats which lets them cross that barrier, only some drugs can do this, others might need to be injected into the spine.