The combination of lapatinib and letrozole delays the progression of metastatic breast cancer in postmenopausal women erbB2 +.

according to a study presented at an international conference on breast cancer

The combination of lapatinib (Tyverb ®) and letrozole (an aromatase inhibitor) as first-line treatment slows the progression of metastatic breast cancer erbB2 positive compared with letrozole alone [i], according to a study presented in San Antonio 31 Breast Cancer Symposium (SABCS).

Lapatinib (Tyverb ®) is available in Spain this month for breast cancer patients with advanced or metastatic erbB2 + tumor which had progressed after previous treatment with anthracyclines, taxanes and trastuzumab [ii] for metastatic disease and for which so far there was no other treatment alternative. This drug, GlaxoSmithKline (GSK) is administered to these patients in combination with capecitabine.

EGF30008 The study presented in SABCS is esnsayo a clinical phase III, double-blind, randomized, placebo involving 1286 postmenopausal women with metastatic breast cancer with hormone receptor positive. Some of the patients included in this study also expressed the receptor erbB2. The study patients received either letrozole 2.5 mg once a day plus lapatinib 1500 mg, or 2.5 mg of letrozole plus placebo. The first objective of this study was to verify the disease-free survival in the subgroup of people who had also overexpress the erbB2 receptor and the secondary variables such as progression-free survival in the group of patients. Other secondary variables were: overall response rate, clinical benefit rate, time to response, duration, overall survival, safety and quality of life. Hormone therapy was permitted only in the group receiving adjuvant treatment (1 year before entering the study).

The patients experienced 5.2 months increase in survival free of disease progression compared with women treated with letrozole alone (8.2 months vs. 3). Across the group that received lapatinib treatment with letrozole, irrespective of whether it was to overexpress the erbB2 receptor or not, the average progression-free survival was more than a month with letrozole alone (11.9 months vs. 10.9).

The combination of letrozole and lapatinib was safe and no serious adverse effects were identified. Adverse effects of grade 3 / 4 occurred in 2% of patients in the group receiving the combination as in monotherapy, and included diarrhea, back pain, fatigue and increased transaminases (ALT and AST).

The growth factor receptors, such as those belonging to the erbB family play a key role in growth and cell survival [iii]. The recipient can go to these proteins is a way to remove the tumor cells and prevent tumor growth. About 70% of breast cancers are hormone receptor positive and only one third of them responded to treatment with aromatase inhibitors. Even many of the responding tumors may become resistant, leading to tumor progression and, ultimately, the death of the patient [iv]. Recent studies have revealed interactions between hormone receptors and erbB receptors, as major contributors to the development of resistance, and have served as a baseline scenario for this study [v].

Breast cancer erbB2 +

Breast cancer erbB2 + affects almost half (44% -48%) of patients younger than 40 years and one quarter of all breast cancer patients [vi] [vii]. One of the most aggressive of worse prognosis and therefore at higher risk of recurrence and mortality. About half of patients with metastatic breast cancer erbB2 + does not respond to existing therapies to date and the most responsive patients show disease progression during the year following the tratamiento4 5. So far, no other therapeutic alternatives for these patients.


Unlike other treatments available for this type of cancer, lapatinb is the first oral targeted therapy, allowing patients to take treatment at home. Lapatinib presents a novel mechanism of action: it acts from inside the cell, inhibiting both andalusia andalusia ErbB1 and erbB2 receptor, both responsible for the growth and proliferation tumoral6 7. Being able to act from inside the cell, lapatinib is not affected by any changes or the presence of mutations in the extracellular domain of receptor8.


GlaxoSmithKline (GSK)


GSK is a pharmaceutical company engaged in research and development of new cancer treatments that can make important changes in the lives of patients. GSK has one of the portfolios of drugs in solid research oncology sector. The research effort GSK Oncology includes working with over 160 cancer centers worldwide. GSK is investigating various methods of treatment against cancer, both those focused on prevention, as in the palliative treatment, chemotherapy and targeted therapies against specific molecular targets.