Iniparib Promising in Metastatic Triple-negative Breast Cancer

Iniparib Promising in Metastatic Triple-negative Breast Cancer

Treatment with the investigational drug iniparib in addition to chemotherapy appears to extend survival by almost five months compared with chemotherapy alone for women with metastatic triple-negative breast cancer. These results were presented at the 35th European Society for Medical Oncology (ESMO) Congress.

Breast cancers that are estrogen receptor-negative, progesterone receptor-negative, and HER2-negative are called triple-negative breast cancers. Triple-negative breast cancers tend to be more aggressive than other breast cancers and have fewer treatment options.

Iniparib belongs to a class of drugs called PARP inhibitors. The PARP enzyme plays a role in DNA repair, including the repair of DNA damage from chemotherapy. Drugs that inhibit this enzyme may contribute to cancer cell death and increased sensitivity to chemotherapy. Iniparib is currently in clinical trials for the treatment of certain kinds of breast cancer, included triple-negative breast cancer. As well, iniparib is being evaluated in squamous cell nonsmall cell lung cancer and pancreatic, ovarian, and brain cancers.

Researchers involved in this Phase II trial evaluated 123 women with metastatic triple-negative breast cancer who had received as many as two previous treatment regimens. They were divided into two treatment groups: one group received chemotherapy with Gemzar® (gemcitabine) and carboplatin plus iniparib, and the other group received chemotherapy alone.

  • Overall survival was improved by almost five months among patients receiving chemotherapy plus iniparib compared with those receiving chemotherapy alone: 12.3 months versus 7.7 months, respectively.
  • More than half (55.7%) of the women receiving iniparib experienced a clinical benefit (complete or partial response or stable disease for at least six months) compared with 33.9% of those receiving chemotherapy alone.
  • Side effects were similar between both treatment groups.

These data are promising and suggest that iniparib may provide a potential new treatment option for patients with metastatic triple-negative breast cancer, which currently has limited therapeutic options, concluded one researcher on the study. The researchers add that questions remain about iniparib, which are being addressed in ongoing clinical trials. Of particular interest is determining which chemotherapy drugs will be most effectively combined with iniparib.

Reference: OShaughnessy J, et al. Iniparib extends overall survival in metastatic triple-negative breast cancer: final Phase-II results.  Presented at the 35th European Society for Medical Oncology (ESMO) Congress, Milan, Italy, October 8-12, 2010. Abstract LBA11.

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