taxane
Meaning of taxane: Yew-derived chemotherapy that freezes the cell's internal scaffolding solid, which is the opposite of what the other scaffolding drugs do.
Definition of taxane
A taxane is a chemotherapy drug, first obtained from yew trees, that binds to microtubules and locks them in place. Microtubules are hollow protein tubes a cell builds and dismantles continually, and they have to be able to shorten in order to drag chromosomes apart as the cell divides. Held rigid they cannot, so division stalls halfway and the cell dies.
How do they stop a cell dividing?
A dividing cell assembles its microtubules into a spindle, hooks them onto the duplicated chromosomes and then shortens them to haul one full set toward each end. The whole apparatus depends on tubes that can grow and shrink from moment to moment. A taxane clamps onto the inner wall of the tube and prevents it coming apart, so the spindle sets like cement. Chromosomes cannot be separated, the checkpoint that watches for exactly this problem holds the cell in place, and the cell eventually triggers its own destruction. Fast-dividing tissue suffers most, which is why mitosis is where the effect concentrates.
How do they differ from the other spindle drugs?
| Drug group | Effect on microtubules | Result |
|---|---|---|
| Taxanes | Prevent them coming apart | Spindle frozen in place |
| Vinca alkaloids | Prevent them assembling | Spindle never forms |
| Eribulin | Blocks growth at the tube ends | Spindle stalls part-built |
The directions are opposite and the outcome is the same, which is the point most often garbled in short descriptions. All three are grouped together as an antimicrotubule agent because they share the target, not the mechanism.
Where do they come from, and what do they cost?
The first member was extracted from the bark of the Pacific yew, a slow-growing tree that had to be killed to harvest it, and the supply problem was severe enough to hold up development. It was solved by building the drug from a related compound in yew needles, which regrow, and later members are made the same way. The drugs are poorly soluble in water and need a strong solvent, which is itself responsible for many of the allergic-type reactions seen during infusion and is the reason a formulation bound to albumin was developed. Nerve damage in the hands and feet is the effect that most often limits dose, together with suppression of the marrow and hair loss. Taxanes are widely used in breast cancer among other tumors.
Also known as
Used in a sentence
A taxane was added to the regimen once the first course was completed.
Good to know
Taxanes and vinca alkaloids both disable the spindle but act in opposite directions, taxanes by stopping microtubules coming apart and vinca alkaloids by stopping them forming, and nerve damage in the hands and feet is the toxicity that most often limits taxane dose.
Word origin
Where “taxane” comes from
The name comes from Taxus, the Latin name of the yew tree, from whose bark the first member of the group was extracted.