Lapatinib Shows Activity Against Inflammatory Breast Cancer

NEW YORK (Reuters Health) - New research suggests that lapatinib, an inhibitor of epidermal growth factor receptor tyrosine kinases, may be an effective treatment for HER2-overexpressing relapsed or refractory inflammatory breast cancer.

Although none of the patients experienced a complete response to the drug, 39% had a partial response, defined as a 50% drop in the extent of skin disease. Side effects, however, were fairly common, including a few fatal complications that may have been drug related.

Inflammatory breast cancer is known to be a highly aggressive malignancy and for patients with resistance to first-line chemotherapy, treatment options are limited, according to the report in the April 27th online issue of The Lancet Oncology.

In an earlier study of 30 patients, treatment with lapatinib produced a 50% response rate, lead author Dr. Bella Kaufman, from The Chaim Sheba Medical Center in Tel Hashomer, Israel, and colleagues note. To better gauge the effectiveness of the drug, the cohort was expanded to 126 patients.

Subjects in the phase II, open-label study were treated with lapatinib 1500 mg once daily. The skin disease response was assessed every 4 weeks and the response in sites of locally advanced or metastatic disease was evaluated every 8 weeks using the response evaluation in solid tumors (RECIST) criteria.

The median progression-free survival and duration of response were 14.6 and 20.9 weeks, respectively. Prior treatment with trastuzumab did not affect the likelihood of a lapatinib response.

Ninety-two percent of patients had at least one adverse event during treatment. Nearly one third of patients had a serious event, most often dyspnea and pleural effusion. Five patients died from adverse events that may have been drug related.

"Lapatinib monotherapy," the authors conclude, "is potentially clinically effective in heavily pretreated patients with inflammatory breast cancer with HER2+ tumors. The objective response rate noted in these treatment-refractory patients coupled with the median duration of response and median overall survival supports a role for lapatinib in these patients."