Dacomitinib (PF299804, PF299)S

PF299804 is a specific inhibitor of the ERBB family of kinases. PF299804 inhibits EGFR signaling and induces apoptosis in the EGFR T790M-containing H3255 GR cell line. PF299804 is effective in gefitinib-sensitive and gefitinibresistant NSCLC cell lines. PF299804 inhibits the growth of H3255 and HCC827 cells engineered to express EGFR T790M. PF299804 inhibits EGFR phosphorylation in the presence of the T790M mutation. ^[1] PF-299804 is believed to irreversibly inhibit ERBB tyrosine kinase activity through binding at the ATP site and covalent modification of nucleophilic cysteine residues in the catalytic domains of ERBB family members. ^[2] PF299804 shows significant growth-inhibitory effects in HER2-amplified gastric cancer cells (SNU216, N87), and it has lower 50% inhibitory concentration values compared with other EGFR tyrosine kinase inhibitors, including gefitinib, lapatinib, BIBW-2992, and CI-1033. PF299804 induces apoptosis and G1 arrest and inhibits phosphorylation of receptors in the HER family and downstream signaling pathways including STAT3, AKT, and extracellular signal-regulated kinases (ERK) in HER2-amplified gastric cancer cells. PF299804 also blocks EGFR/HER2, HER2/HER3, and HER3/HER4 heterodimer formation as well as the association of HER3 with p85α in SNU216 cells. ^[3] A recent research uses forty-seven human breast cancer and immortalized breast epithelial lines to evaluate the inhibition effects of PF299804, the results indicate PF299804 preferentially inhibits growth of HER-2-amplified breast cancer cell lines than nonamplified lines (RR = 3.39, p < 0.0001). PF299804 reduces the phosphorylation of HER2, EGFR, HER4, AKT, and ERK in the majority of sensitive lines. PF299804 exerts its anti-proliferative effect through a combined G0/G1 arrest and an induction of apoptosis. ^[4]