The presence of the protein poly (ADP-ribose) polymerase (PARP) in tumors can help predict their response to chemotherapy, a German scientist told the seventh European Breast Cancer Conference (EBCC7) in Barcelona. Professor Gunter von Minckwitz, from the German Breast Group Forschungs GmBH, Neu-Isenburg, said that, contrary to the current belief that PARP is associated with a limited number of tumors, he and his team found for the first time that PARP expression exists across all breast cancer subtypes, and that such tumors were highly sensitive to chemotherapy.

von Minckwitz and his team set out to investigate the expression of PARP in various hormone receptor subtypes of early breast cancer and to evaluate whether or not it could predict a total response to chemotherapy given before surgery. "We knew that a new class of drug called PARP inhibitors were effective against aggressive types of breast cancer such as those involving BRCA mutations and triple-negative breast cancer, where the tumor does not express genes for the estrogen or progesterone receptors, or for HER2," he said. "However, we didn't understand whether the presence of PARP would predict the efficacy of these drugs. Before exploring this, we needed to understand whether PARP played any role in breast cancers, whether it was restricted to particular types of tumors, how it correlated to existing prognostic and predictive markers, and whether it could predict the efficacy of chemotherapy."