Lapatinib (ditosylate)

Lapatinib ditosylate (GW572016 ditosylate) is a potent inhibitor of the ErbB-2 and EGFR tyrosine kinase domains with IC₅₀ values against purified EGFR and ErbB-2 of 10.2 and 9.8 nM, respectively^[1]. IC50 & Target:IC50: 10.2 nM (EGFR), 9.8 nM (ErbB2)^[1] In Vitro: Lapatinib (GW2016; 0.03-10 µM; 6 hours; BT474 and HN5 cells) treatment inhibits receptor autophosphorylation of EGFR and ErbB-2 in a dose-responsive manner. Phosphorylation of serine 473 of AKT was inhibited by GW2016 in a dose-dependent manner^[1].
Lapatinib (GW2016; 72 hours; HN5, A-43, BT474, N87, and CaLu-3 cells) treatment has a selective inhibition of the proliferation of human tumor cell lines^[1].
Lapatinib (GW2016; 1-10 µM; 72 hours; HN5 cells) treatment results in induces G1 arrest^[1]. In Vivo: Lapatinib (GW2016; 30-100 mg/kg; oral administration; twice daily; for 21 days; CD-1 nude female mice) treatment inhibits tumor xenograft growth of the HN5 cells in a dose-responsive manner at 30 and 100 mg/kg, with complete inhibition of tumor growth at the higher dose^[1].