Selectide-18

Selectide-18 is a novel 18-residue mimetic peptide designed to specifically inhibit the p110β isoform of phosphoinositide 3-kinase (PI3K). Developed by researchers at the Fralin Biomedical Research Institute at Virginia Tech Carilion, the drug targets the interaction between the PI3K regulatory subunit p85α and the catalytic subunit p110β. By binding to p85α, Selectide-18 prevents the assembly of the active PI3K complex, thereby inhibiting the PI3K pathway which is often overactive in high-grade gliomas. Unlike many pan-PI3K inhibitors that exhibit toxicity due to off-target inhibition of other isoforms (α, δ, γ), Selectide-18 demonstrates high specificity for p110β with an IC50 of approximately 100nM. It has shown efficacy in killing glioblastoma cell lines with high p110β activity while sparing those with low activity in preclinical models.