36 out of 100
A 47- year old woman with choriocarcinoma is treated with very high doses of methotrexate (MTX). You anticipate significant host cell toxicity in response to the high MTX dose, and so immediately after giving the anti-cancer drug, you administer which of the following? (AIPG 2009)
Ans. B Leucovorin
- This essential technique to reduce host cell toxicity in response to MTX therapy is known as leucovorin rescue.
- Methotrexate, a folic acid analog/antimetabolite, can be curative for women with choriocarcinoma and is also useful for non-Hodgkin’s lymphomas and acute lymphocytic leukemias in children.
- The drug kills responsive cancer cells by inhibiting dihydrofolate, an enzyme necessary for forming tetrahydrofolic acid .
- To protect normal cells we administer leucovorin (also called citrovorum factor or folinic acid) right after giving the MIX. It is taken up by the normal cells, bypasses the block induced by the MTX, and so spares normal cell metabolism. The leucovorin does not spare cancer cells: just as they cannot take up MTX well, they cannot take up the rescue agent and save themselves from cytotoxicity.