Lapatinib promising for advanced ErbB2-amplified breast cancer

July 8, 2008

NEW YORK (Reuters Health) - In a phase II trial, the investigational agent lapatinib was well tolerated and showed clinical activity as first-line therapy against locally advanced or metastatic breast cancer in women with ErbB2-amplified disease, investigators report.

They note in their paper in the June 20 issue of the Journal of Clinical Oncology that lapatinib is an oral, selective inhibitor of epidermal growth factor receptors ErbB1 and ErbB2, or Her-1 and HER-2/neu.

Dr. Henry L. Gomez of the Instituto Nacional de Enfermedades in Lima, Peru, led an international study of 138 patients with ErbB2-amplified locally advanced or metastatic breast cancer who were randomized to either lapatinib 1500 mg once daily or lapatinib 500 mg twice daily.

Clinical response was assessed at 8 and 12 weeks and then every 12 weeks until there was disease progression or until the drug was discontinued for another reason.

Median treatment time was 17.6 weeks. The overall response rate (i.e., complete plus partial response rates) was 24%, and 31% of patients showed clinical benefit (complete response, partial response or stable disease for at least 24 weeks).

The median time to response was 7.9 weeks. The progression-free survival rate was 63% at 4 months, and 43% at 6 months.

The most common drug-related adverse events were diarrhea, rash, pruritus and nausea. These events were primarily grade 1 or 2.

There were no significant differences in clinical activity or the adverse event profile between the dosing schedules.

The investigators conclude that the results support further evaluation of lapatinib in first-line treatment of early-stage ErbB2-overexpressing breast cancer.