How do antifolates work re leukemia?

[blueplusgreen]

How do antifolates work re leukemia? I don't understand how healthy blood cells can get enough folate to mature when the same body's cancerous blast cells are being starved of it. Without folate, an otherwise healthy person gets anemic. How does this not apply to cancer patients? Can someone please explain?

The rapidity of cell division is listed as the reason but I would appreciate a little more explanation, an analogy, sumpin'!

Is it like giving the parent healthy blood cell and blast cell each a million bucks and each give their daughter cells each half and so on? So the faster the quicker blast cells procreate, the less the kids get? Can't the daughters go get their own supply? I don't understand! Please enlighten me!

Thanks in advance.

 

[jim mcnamara]

Antifolates act mostly during DNA and RNA synthesis. They interfere during the
S-phase of the cell cycle. So, there is a greater toxic effect on rapidly
dividing cells, than on cells that are not busy dividing.

These dividing cells in humans are largely the malignant and myeloid cells, and
cells lining the gastrointestinal tract. Since these guys replicate their DNA
more frequently, the drugs like methotrexate largely slow the growth and
proliferation of these cancerous cells. And mucosal cells, too.

Because the effect is pervasive there are a lot of possible side-effects, too.

 

[blueplusgreen]

Thank you! But I'm dense. Can you clarify a little more? I was reading how Sidney Farber injected almost comatose kids with aminopterin and they got out of bed and played (for a few months). Is it just that there is so much folate in a body--even in the presence of an antifolate-- that the healthy red blood cells are able to grab enough of it to replicate fully and live about 120 days which is about how long Farber's remissions lasted? And the malignant cells (and mucosal) that keep dividing get weakened cause there isn't enough left over? Is there some equation that shows how much folate a healthy cell needs versus a malignant one?