Invasive Breast Lobular Carcinoma

This phase II trial tests how well neratinib prior to the primary treatment (neoadjuvant) works in treating patients with stage I-III HER2 mutated lobular breast cancers. Neratinib is in a class of medications called kinase inhibitors. It works by blocking the action of an abnormal protein that signals cancer cells to multiply. This helps slow or stop the spread of cancer cells. Giving neratinib in addition to normal therapy may work better in treating cancer than the endocrine therapy patients would normally receive.