Recent Advances in PI3 Kinase Inhibitors: Anticancer Activities and Structure-Activity Relationships

Phosphatidyl-inositol-3-kinase (PI3K) has emerged as a potential therapeutic target for the development of novel anticancer drugs. The dysregulation of PI3K has been associated with many human malignancies such as breast, colon, endometrial, brain, and prostate cancers. The PI3K kinases in their different isoforms, namely α, β, δ, and γ, encode PIK3CA, PIK3CB, PIK3CD, and PIK3CG genes. Specific gene mutation or overexpression of the protein is responsible for the therapeutic failure of current therapeutics. Recently, various PI3K signaling pathway inhibitors have been identified, which showed promising therapeutic results by acting on specific isoforms of the kinase too. Several inhibitors containing medicinally privileged scaffolds like oxadiazole, pyrrolotriazine, quinazoline, quinazolinone, quinazoline-chalcone hybrids, quinazoline-sulfonamide, pyrazolochalcone, quinolone hydroxamic acid, benzofuropyridinone, imidazopyridine, benzoxazines, dibenzoxanthene, indoloderivatives, benzimidazole, and benzothiazine derivatives have been developed to target the PI3K pathway and/or a specific isoform. The PI3K inhibitors under clinical trial studies include GDC-0032, INK1117 for PI3K-α, and AZD8186 for PI3K-β. This review primarily focuses on the structural insights, anticancer activities, and structure-activity relationship (SARs) studies of recent PI3K inhibitors, including their clinical stages of development and therapeutic values.