Abstract
Phosphatidylinositol-3-kinases (PI3Ks) constitute an important validated therapeutic class involved in crucial cellular processes, and their dysregulation is associated with cancer initiation and progression. Nonetheless, intrinsic and acquired resistance mechanisms associated with PI3K pathway modulation have underscored the need for alternative therapeutic strategies. In this context, recent studies have shown that simultaneous inhibition of PI3K and histone deacetylases (HDAC) promotes synergistic antitumor effects in different cancer cell lines. HDACs are validated epigenetic targets that are extensively explored in clinical practice and have a pharmacophore with versatility for structural modifications, which facilitates the design of multitarget inhibitors. This review examines the rational design and synthetic evolution of dual PI3K/HDAC inhibitors, an area catalyzed by the development of fimepinostat, the first clinically evaluated agent exhibiting potent and balanced inhibition of both targets. We provide a critical overview of PI3K/HDAC multitarget inhibitors reported in recent years that have progressed to preclinical or clinical investigation, discussing the structural frameworks employed, medicinal chemistry strategies adopted, and structure-activity relationships established. Particular attention is given to advantageous molecular features as well as challenges related to toxicity, pharmacokinetic behavior, and pharmacodynamic modulation. From this comprehensive analysis, we outline key considerations and emerging design principles that may inform the next generation of PI3K/HDAC multitarget drug candidates. Insights derived from the diversity of chemical scaffolds, activity profiles, and selectivity patterns described herein may support the development of innovative therapeutic agents capable of overcoming current limitations in anticancer treatment.