Structural Insights into the Development of Inhibitors Against Cancer-Specific Mutations of PI3Kα.

Phosphoinositide 3-kinase alpha (PI3Kα) is a pivotal regulator of cell growth, proliferation, and survival. Dysregulation of the PI3K/AKT/mTOR pathway, driven predominantly by PIK3CA mutations (e.g., H1047R, E542K, and E545K), is a hallmark of many cancers. Advances in structural, biochemical, and computational studies have elucidated mutation-specific conformational changes of PI3Kα. While early pan- and isoform-selective PI3K inhibitors (alpelisib) show clinical utility, their intrinsic toxicity and resistance to treatment persist. Recent breakthroughs include the emergence of allosteric inhibitors (RLY-2608 and STX-478) that exploit mutation-induced cryptic pockets to achieve mutant selectivity as well as covalent inhibitors and degraders (inavolisib) that enhance specificity, aiming at decoupling antitumor activity from metabolic dysfunction. This review synthesizes current progress in PI3Kα inhibitor development, emphasizing structural characteristics, clinical challenges, and emerging strategies. Addressing challenges to increase mutant selectivity, exploring conformational modulation, uncovering new mechanisms of action, and implementing personalized therapies are key future directions for PI3Kα-targeted drug discovery.