“Half of patients with metastatic triple-negative breast cancer (TNBC) achieved disease control when treated with the combination of a poly (ADP-ribose) polymerase (PARP) inhibitor and an anti–PD-1 agent, a preliminary prospective study showed.
“Overall, 13 of 46 evaluable patients had objective responses to treatment with niraparib (Zejula) and pembrolizumab (Keytruda). An additional 10 patients had stable disease. Clinical activity was observed in patients beyond those with germline BRCA mutations.”
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.