Biomarker linked to survival and treatment for BRCA-positive breast cancer patients

June 8, 2016 | by H. Chung So

Jeffrey Weitzel Jeffery Weitzel, M.D.

For breast cancer patients with BRCA gene mutations, compounds called poly ADP ribose (or PAR) can help determine treatment response and clinical outcomes.

This new finding in a study led by Jeffrey Weitzel, M.D., director, Division of Clinical Cancer Genetics, was presented at this year’s American Society of Clinical Oncology’s annual meeting in Chicago.

PAR is produced by enzymes called PARP, which are also involved in DNA repair and programmed cell death. Cancer cells can also exploit PARP to repair themselves after DNA damage from radiation or chemotherapy.

To address this, a new class of drugs called PARP inhibitors has been developed to thwart this self-repair process, which can enhance current cancer therapies or kill the cancer cells outright.

In this study, 72 patients with BRCA-associated metastatic breast cancer were treated with either veliparib, a PARP inhibitor, on its own or with carboplatin, a chemotherapy drug. The patients also had their PAR levels measured before treatment, three hours after treatment and at additional times later on.




Veliparib molecular formula Veliparib molecular formula




After capturing and analyzing these measurements, Weitzel and his team found that patients who survived longer or had better treatment responses either have higher PAR levels before treatment or greater drop in PAR levels after the initial veliparib therapy.

In discussing the study, Weitzel said these findings can be used to determine which breast cancer patients are most likely to benefit from PARP inhibitor therapy, and is currently studying whether this therapy will be beneficial as a first-line treatment or in BRCA-associated breast cancer in earlier stages.

This study’s abstract is available on the ASCO website


Learn more about City of Hope's breast cancer treatments and research. If you are looking for a second opinion or consultation about your treatment, request an appointment online or contact us at 800-826-HOPE. Please visit Making Your First Appointment for more information.

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