New results from a study in metastatic breast cancer showed that the combination of lapatinib plus letrozole as a first-line treatment significantly delayed disease progression compared with letrozole plus placebo. Success of the new drugs depends on the type of hormone receptors that the patient has. These hormone receptors vary from patient to patient. Receptors are sites on the cell surface that can allow the cell to interact with a specific hormone and in this instance are called ErbB2 or HER2 receptors. These receptors are important as they are involved in the mode of cancer progression. If you are positive for these receptors (i.e. your cells have them), then you are more likely to have a better response to this specific form of treatment. More of these drugs that operate at the receptor level are becoming available and so it is useful to see the results from the latest studies.
In this study, women with postmenopausal, hormone receptor-positive and ErbB2 (HER2)-positive metastatic breast cancer experienced a 5.2 month increase in median progression-free survival compared with those treated with letrozole alone.
Lapatinib is a new biological form of therapy against breast cancer. The results of this study are very exciting and demonstrate that breast cancer outcome in women with hormone sensitive breast cancer that is also positive for Her-2 can be improved further by adding lapatinib to an aromatase inhibitor. Although this study was carried out in the setting of breast cancer that had already spread elsewhere (metastatic), future studies are very likely to demonstrate a similar benefit in women with early breast cancer. The study represents another step towards personalised breast cancer treatment.