Overview Neratinib +/- Fulvestrant in Metastatic HER2 Non-amplified But HER2 Mutant Breast Cancer Status: Completed Trial end date: 2021-03-11 Target enrollment: Participant gender: Summary This phase II study will test cancer to see if it has a HER2 mutation and, if so, see how HER2 mutated cancer responds to treatment with neratinib. Phase: Phase 2 Details Lead Sponsor: Washington University School of MedicineCollaborators: Puma Biotechnology, Inc.United States Department of DefenseTreatments: EstradiolFulvestrantTrastuzumab