Neoadjuvant Neratinib in Stage I-III HER2-Mutated Lobular Breast Cancers

This study is testing a targeted drug called neratinib given before surgery (neoadjuvant therapy) in patients with early-stage hormone receptor-positive lobular breast cancer that carries a specific HER2 gene mutation. Lobular breast cancer is a type that grows in a different pattern than the more common ductal breast cancer, and this trial focuses on cases where a HER2 mutation (not amplification) is driving tumor growth. **You may be eligible if:** - You are 18 years or older - You have been newly diagnosed with early-stage (stage I–III) hormone receptor-positive lobular breast cancer confirmed by biopsy - Your tumor has a confirmed HER2-activating mutation (not just HER2 amplification) detected by a certified lab - Your tumor is at least 1.5 cm in size - You are in good physical health (ECOG 0–1) with adequate blood, kidney, and liver function - You have not yet received treatment for this cancer **You may NOT be eligible if:** - Your cancer has spread to distant parts of the body (metastatic) - Your tumor does not have a confirmed HER2-activating mutation - Your tumor is HER2-amplified (IHC 3+ or FISH positive) rather than HER2-mutated - Your organ function does not meet the required thresholds Talk to your doctor to see if this trial is right for you.