Therapeutic Response

ER positive, HER2-positive, and PR positive status confers therapeutic sensitivity to Lapatinib in combination with Letrozole in patients with Invasive Breast Carcinoma.

Statements

Source and description
Tyverb (lapatinib) [product information]. EMA. The European Medicines Agency (EMA) has authorized laplatinib in combination with an aromatase inhibitor for postmenopausal women with hormone receptor positive metastatic disease, not currently intended for chemotherapy. This indication states that the patients in the registration study were not previosuly treated with trastuzumab or an aromatase inhibitor and that no data are available on the efficacy of this combination relative to trastuzumab in combination with an aromatase inhibitor in this patient population. This indication is based on the randomized, double-blind, and placebo controlled phase 3 study EGF30008, which used Letrozole as an aromatase inhibitor. Lapatinib's product information sheet further defines HER2 (ErbB2) overexpressing tumors as IHC3+, or IHC2+ with gene amplification or gene amplification alone.
Tykerb (lapatinib) [package insert]. FDA. The U.S. Food and Drug Administration granted approval to lapatinib in combination with letrozole for the treatment of patients who are postmenopausal women with hormone receptor-positive metastatic breast cancers that overexpresses the HER2 receptor for whom hormonal therapy is indicated. Lapatinib's product label notes that lapatinib in combination with an aromatase inhibitor has not been compared to a trastuzumab-containing chemotherapy regimen for the treatment of metastatic breast cancer.