Compared with chemotherapy alone, treatment with a combination of chemotherapy and the investigational drug iniparib improved overall survival by more than four months among women with metastatic, triple-negative breast cancer. The results of this Phase II clinical trial were published in the New England Journal of Medicine.
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.
To evaluate iniparib in the treatment of advanced, triple-negative breast cancer, researchers conducted a Phase II clinical trial among 123 patients. Study participants were treated with either chemotherapy alone or chemotherapy plus iniparib. In both groups, chemotherapy consisted of Gemzar® (gemcitabine) and carboplatin.
- Overall survival was 7.7 months among women treated with chemotherapy alone and 12.3 months among women treated with chemotherapy plus iniparib.
- Progression-free survival was 3.6 months among women treated with chemotherapy alone and 5.9 months among women treated with chemotherapy plus iniparib.
- A clinical benefit (complete or partial disappearance of the cancer or stable disease lasting for at least six months) was observed in 34% of women treated with chemotherapy alone and 56% of women treated with chemotherapy plus iniparib.
- Side effects were similar in the two treatment groups.
The researchers concluded that the addition of iniparib to chemotherapy improved survival among women with metastatic, triple-negative breast cancer. On the basis of these results, iniparib is being further evaluated in a Phase III clinical trial.
Reference: O’Shaughnessy J, Osborne C, Pippen JE et al. Iniparib plus chemotherapy in metastatic, triple-negative breast cancer. New England Journal of Medicine [early online publication]. January 5, 2011.