December 16, 2009

Neratinib Shows Promise in Treatment of HER2-positive Breast Cancer


According to the results of a Phase II clinical trial, the addition of the investigational drug neratinib to paclitaxel chemotherapy produced promising response rates among women with metastatic, HER2-positive breast cancer. These results were presented at the 2009 San Antonio Breast Cancer Symposium.

Twenty to 25 percent of breast cancers overexpress (make too much of) a protein known as HER2. Overexpression of this protein leads to increased growth of cancer cells and a worse breast cancer prognosis. Fortunately, the development of drugs such as Herceptin® (trastuzumab) that specifically target HER2-positive cells has improved prognosis for women with HER2-positive breast cancer.

Neratinib is an investigational, oral medication that targets HER2 as well as HER4 and the epidermal growth factor receptor (EGFR).

To evaluate the safety and efficacy of neratinib in combination with paclitaxel chemotherapy, researchers conducted a Phase I/II trial among women with metastatic, HER2-positive breast cancer. The first part of the study established the dose of neratinib that can be used, and the second part evaluated treatment response rate.

Some of the study participants had received prior treatment for metastatic breast cancer, and others had not.

The study is ongoing, but at the time of the current analysis, information was available for 99 patients treated with a combination of paclitaxel and neratinib.

* 69% of patients experienced a partial or complete reduction of detectable cancer following treatment. Overall response rate was 70% among patients who had not been previously treated for metastatic breast cancer and 68% among patients who had been previously treated.
* Progression-free survival was roughly one year (52.1 weeks).
* The most common side effect was diarrhea, which affected 91% of patients.

These results suggest that the combination of neratinib and paclitaxel is active against metastatic, HER2-positive breast cancer. Based on these results, a Phase III clinical trial is underway to compare this combination to Herceptin plus paclitaxel in the first-line (initial) treatment of advanced, HER2-positive breast cancer.

Reference: Chow L, Gupta S, Hershman DL et al. Safety and efficacy of neratinib (HKI-272) in combination with paclitaxel in ErbB2+ metastatic breast cancer. Presented at the 32nd CTRC-AACR San Antonio Breast Cancer Symposium. December 9-13, 2009. San Antonio, TX. Abstract 5081.

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