Abstract The PI3K pathway has long remained a fertile ground for drug discovery in cancer, including in estrogen receptor positive metastatic breast cancer. It has also remained a pathway difficult to drug effectively due to on target toxicities. New strategies to overcome these toxicities have manifested in novel drug types and management strategies for patients. Here I discuss the PI3K pathway in signaling and oncogenesis, current therapies inhibiting PI3K, mechanisms limiting efficacy, and increasing the PI3K therapeutic window with a focus on mutant selective PI3K inhibitors. Finally, I will expound on the translational future of the PI3K field, highlighting advances in biomarker discovery, tumor correlative analysis, and patient advocacy. Citation Format: N. Vasan. PI3K past, present, and future abstract. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr ED10-01.