PARP inhibitor
Meaning of PARP inhibitor: PARP inhibitors block an enzyme that helps repair DNA damage, a strategy especially effective against cancers already missing a separate repair pathway.
Definition of PARP inhibitor
A PARP inhibitor is a medication that blocks poly ADP-ribose polymerase, an enzyme cells normally use to repair small, everyday breaks in DNA. When this repair pathway is blocked, a cell must rely on other mechanisms to fix its DNA, and unrepaired damage can accumulate to the point that the cell dies.
This vulnerability is most pronounced in cancers carrying a BRCA1 or BRCA2 mutation, since those genes normally support a separate DNA repair pathway. Combining a PARP inhibitor with an existing BRCA defect can leave a cancer cell with no working way to fix its DNA, an approach known as synthetic lethality.
PARP inhibitors are used to treat certain ovarian, breast, prostate, and pancreatic cancers linked to these mutations, generally taken by mouth over an extended course, while healthy cells with intact repair pathways tend to tolerate the same drug more easily.
Also known as
Used in a sentence
The oncologist discussed adding a PARP inhibitor after genetic testing confirmed a BRCA mutation in the tumor.
Good to know
PARP inhibitors work best against cancers that already carry a BRCA mutation or similar defect in DNA repair, so testing for that mutation generally guides whether this drug class is likely to help.