Biological Activity
Neratinib is an orally available, irreversible tyrosine kinase inhibitor with IC50s of 59 nM and 92 nM for HER2 and EGFR, respectively.
In Vitro
Neratinib has inhibition of tyrosine kinases KDR and Src with IC50 of 0.8 μM and 1.4 μM, respectively, being 14- and 24-fold less active compared with HER2. Neratinib displays no activity against other serine-threonine kinases such as Akt, cyclin D1/cdk4, cyclin E/cdk2, cyclin B1/cdk1, IKK-2, MK-2, PDK1, c-Raf, and Tpl-2, as well as the tyrosine kinase c-Met. Neratinib selectively inhibits the proliferation of 3T3 cells transfected with the HER2 (3T3/neu), as well as two other HER-2-overexpressing SK-Br-3 and BT474 cells with IC50 values of 2-3 nM, displaying > 230-fold potency compared with non-transfected 3T3 cells as well as MDA-MB-435 and SW620 which are EGFR- and HER2-negative. Neratinib also inhibits the proliferation of EGFR-dependent A431 cells with an IC50 of 81 nM. Neratinib reduces HER2 receptor autophosphorylation in BT474 cells with an IC50 of 5 nM, and EGF-dependent phosphorylation of EGFR in A431 cells with IC50 of 3 nM. Blocking of HER-2 by Neratinib results in inhibition of downstream MAPK and Akt pathways with IC50 of 2 nM, more potently than Trastuzumab. Neratinib inhibits the cyclin D1 expression and the phosphorylation of the Rb-susceptibility gene production in BT474 cells with IC50 of 9 nM, leading to G1-S arrest and ultimately decreased cell proliferation[1].
In Vivo
Orally treated neratinib significantly inhibits the growth of 3T3/neu xenografts, with inhibition of 34%, 53%, 98%, and 98% at dose of 10, 20, 40, and 80 mg/kg/day, respectively. Consistent with the inhibition of HER-2 phosphorylation by 84% within 1 hour of administration at 40 mg/kg/day, Neratinib inhibits the growth of BT474 xenografts by 70-82%, 67%, and 93% at dose of 5, 10, and 40 mg/kg/day, respectively. Neratinib is also effective against SK-OV-3 xenografts with inhibition of 31% and 85% at 5 and 60 mg/kg/day, respectively. Neratinib is less potent against EGFR-dependent A431 xenografts than HER-2-dependent tumors, with 32% and 44% inhibition at 5 and 20 mg/kg/day, respectively. Neratinib displays little activity against MCF-7 and MX-1 xenografts expressing low levels of HER-2 and EGFR, with only 28% inhibition at 80 mg/kg/day, suggesting that Neratinib has selective activity for cells expressing HER-2 or EGFR[1].
References & source
Published experimental findings depend on the model and assay conditions. They do not guarantee equivalent performance in every application. For laboratory research use only.
