PI3K-alpha (mutant-selective, allosteric)

Class

Mutant-selective, allosteric PI3K-alpha inhibitor

Pathway

PI3K/AKT/mTOR signaling pathway — binds a distinct allosteric pocket to selectively inhibit oncogenic PIK3CA-mutant PI3K-alpha (e.g. H1047R) while sparing wild-type PI3K-alpha, avoiding the on-target hyperglycemia/metabolic dysfunction seen with pan-PI3K-alpha inhibitors such as alpelisib

PI3K-alpha (phosphoinositide 3-kinase alpha, encoded by the gene PIK3CA) is an enzyme central to the PI3K/AKT/mTOR pathway, which governs cell growth, metabolism, and survival. Certain PIK3CA mutations, such as H1047R, lock the enzyme in an overactive state, making it one of the most common oncogenic drivers across several solid tumors, including breast cancer. Because this same pathway also mediates normal insulin signaling, earlier inhibitors that block both mutant and wild-type PI3K-alpha (pan-inhibitors) frequently cause metabolic side effects, most notably elevated blood glucose, since they interfere with insulin-driven glucose regulation in healthy tissue. Mutant-selective, allosteric inhibitors are designed to address this trade-off: rather than competing at the enzyme's ATP-binding site, as most kinase inhibitors do, they bind a separate allosteric pocket that is preferentially exposed or stabilized in the mutant conformation. This allows suppression of oncogenic signaling in tumor cells while largely sparing wild-type PI3K-alpha activity in normal tissue, aiming to preserve antitumor effect while reducing metabolic toxicity. This approach is broadly relevant wherever PIK3CA mutations drive tumor growth, offering a potential way to widen the therapeutic window compared with earlier, less selective PI3K-alpha inhibitors.