Agent Treats Inflammatory Breast Cancer
CancerWise - January 2007
In the first international, multi-center clinical trial of a therapy specific to inflammatory breast cancer (IBC), researchers found that an experimental biologic agent, lapatinib, successfully and specifically treats this rare and aggressive form of cancer.
Significance of results
IBC is more likely than other breast cancers to be misdiagnosed, and it is often diagnosed after the cancer has metastasized. Forty percent of patients with the disease survive five years.
Until this study, which is complete, no clinical trials specific to IBC had been conducted, and no effective therapies were known.
“We initiated this Phase II study because lapatinib is one of the few drugs that had shown any activity in Phase I studies in patients with recurrent IBC,” says Massimo Cristofanilli, M.D., associate professor in the Department of Breast Medical Oncology at M. D. Anderson.
Cristofanilli presented findings from the study (Abstract No. 1) at the San Antonio Breast Cancer Symposium in December.
Forty-nine newly diagnosed IBC patients who had never been treated for the disease were enrolled in the study. All had HER2- and/or EGFR-positive IBC, and approximately 25% had metastatic disease.
HER2-positive cancer (which overproduces the HER2/neu, or HER2 protein) occurs in 25% to 30% of breast cancers. It grows faster and is more likely to return than HER2-negative cancers.
EGFR, or epidermal growth factor receptor, is a protein that, when overproduced, can lead to more aggressive breast cancers.
Participants received lapatinib daily for two weeks. They were then given three months of concurrent lapatinib (daily) and paclitaxel chemotherapy (weekly).
Thirty-five of the patients completed the trial and subsequently had surgery, as indicated by the protocol.
The experimental lapatinib-chemotherapy drug regimen had promising results:
- 30 patients, or 86%, had at least a 50% reduction in tumor size
- One patient’s cancer progressed during therapy
- Three of 21 patients who had surgery had no disease at time of surgery
“For IBC patients, these results should be very encouraging because there’s now more of a dedicated research effort for a type of breast cancer that has long been ignored and misunderstood,” Cristofanilli says. “With lapatinib, we finally have a drug on which to build an effective therapy.”
More than 25% of participants responded in the first two weeks when receiving lapatinib alone.
Planned studies likely will include lapatinib in combination with other chemotherapy regimens. Future trials will focus on IBC patients who are HER-2 positive, not EGFR- positive, because HER2-positive cancers responded better to lapatinib in this trial.
Lapatinib is an experimental epidermal growth factor receptor and HER2neu tyrosine kinase inhibitor. This oral agent previously showed promise in patients with metastatic HER2-positive cancer for whom Herceptin, an approved drug for breast cancer, failed. Lapatinib blocks activity of the HER2 protein as well as EGFR by binding to the part of the protein found inside breast cancer cells.
Side effects of lapatinib were mild and manageable. Most common were:
- Skin rash
— From staff reports
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