A class of drugs already in clinical trials for breast and ovarian cancer, so-called PARP inhibitors, may also be effective against some forms of non-small cell lung cancer (NSCLC). Around half of all NSCLC tumors have low levels of ERCC1, a protein that helps repair damaged DNA. PARP inhibitors act by blocking a different DNA repair mechanism. This creates a one-two punch that kills the NSCLC tumor cells that are low in ERCC1, while healthy cells remain relatively unharmed. A recent cell culture study showed that PARP inhibitors like olaparib, niraparib, and BMN 673 killed ERCC1-deficient NSCLC cells, but not cells with normal ERCC1 levels.