Alimta
Meaning of Alimta: The brand name for pemetrexed, a chemotherapy drug given alongside two vitamins that blunt its harshest effects.
Definition of Alimta
Alimta is a brand name for pemetrexed, a chemotherapy drug given by infusion for mesothelioma and for the non-squamous forms of non-small cell lung cancer. It jams several enzymes that use folate to build the parts of DNA, so the cell cannot copy itself and dies. Folic acid and vitamin B12 are given alongside it to reduce its toxicity.
How does it work?
Folate is the delivery service inside a cell for the small carbon fragments needed to build the letters of DNA. Pemetrexed is shaped enough like folate to be carried into the cell in its place, and once inside it disables three separate enzymes on that assembly line rather than one. Starving the cell of DNA parts halts division. Attacking several points at once is why it is described as a multitargeted folate antagonist, and it is what distinguishes the drug from older members of the same family.
Why are vitamins given with it?
Early on, the drug caused severe drops in blood counts and painful mouth ulceration, and some of those effects were dangerous. Investigators noticed that the people worst affected already had poor folate and vitamin B12 stores. Adding folic acid by mouth and vitamin B12 by injection reduced the severe toxicity substantially without weakening the effect on the tumor. A short course of steroid is given too, to prevent a characteristic rash.
What is it used for?
| Disease | Role |
|---|---|
| Non-squamous non-small cell lung cancer | With platinum chemotherapy and often immunotherapy, then continued alone |
| Squamous lung cancer | Not used, because it works poorly in that tissue type |
| Mesothelioma of the chest lining | Long established in combination with cisplatin |
What limits its use?
The kidneys clear the drug largely unchanged, so reduced kidney function raises the level in the blood and the toxicity along with it. Anti-inflammatory painkillers slow that clearance further. Fluid collected in the chest or abdomen, such as a malignant pleural effusion, acts as a reservoir that holds the drug and releases it slowly, which is another reason levels can run higher than expected.
Also known as
Used in a sentence
Alimta was continued as maintenance treatment after four cycles of combination chemotherapy.
Good to know
Pemetrexed works in non-squamous lung cancer but not the squamous form, and the folic acid and vitamin B12 given with it cut serious toxicity without reducing its effect on the tumor.