PIK-75 is a p110α inhibitor with IC50 of 5.8 nM (200-fold more potently than p110β), isoform-specific mutants at Ser773, and also potently inhibits DNA-PK with IC50 of 2 nM.

PIK-75 shows the impressive potency and isoform selectivity at p110α while the corresponding IC50 values are 1300 nM, 76 nM and 510 nM for other PI3K isoforms, p110β, -γ, and -δ, respectively. Furthermore, when binding to purified p110α, PIK-75 is a noncompetitive inhibitor with respect to ATP with Ki of 36 nM and competitive with respect to the substrate PI with Ki of 2.3 nM.PIK-75 also shows potent inhibition of DNA-PK.PIK-75 (1 μM) reduces cell survival by significantly decreasing mitochondrial activity in unstimulated nonasthmatic airway smooth muscle (ASM) cells, asthmatic ASM cells, and lung fibroblasts. While in TGFβ-stimulated ASM cells, PIK75 only decreases mitochondrial activity in asthmatic cells without effects in nonasthmatic cells.A recent study shows that PIK-75 (10 nM) inhibits TNF-α-induced CD38 mRNA expression and significantly attenuates of TNF-α-induced ADP-ribosyl cyclase activity in human airway smooth muscle cells.