This year marks the 25th anniversary of the approval of trastuzumab, the first HER2-targeted therapy for the treatment of HER2-positive breast cancer. The preclinical and clinical development of trastuzumab helped shape the current paradigm in personalized medicine, drug discovery, clinical testing, and product approval. During an American Association for Cancer Research (AACR) Annual Meeting 2023 symposium on Monday, April 17, four scientists who were involved in the discoveries that led to the development of trastuzumab discussed how those discoveries continue to inform cancer research and care. The session, 25th Anniversary of Trastuzumab: Impact and Future Directions, can be viewed on the virtual meeting platform by registered Annual Meeting participants through July 19, 2023.