Varlitinib (ASLAN001) is a potent, reversible, small molecule pan-EGFR inhibitor with IC50 values of 7 nM for HER1, 2 nM for HER2, and 4 nM for HER4.

ErbB2:2 nM, ERB1:7 nM, HER4:4 nM

In cell-based assays involving tumor cells with over-expression of EGFR (A431) or ErbB-2 (BT474), Varlitinib (ARRY-334543) effectively inhibits substrate phosphorylation and demonstrates high selectivity for EGFR/ErbB-2 without significant activity against a panel of 104 other kinases[2].

Varlitinib treatment effectively suppresses tumor growth, achieving complete tumor regression at a dosage of 100 mg/kg administered twice daily. Within five days of treatment, Varlitinib significantly inhibits the phosphorylation of key signaling molecules including HER1-3, RAS/RAF/MEK/MAPK, p70S6K, S6 ribosomal protein, 4EBP1, Cdk-2, Cdc-2, and retinoblastoma. This inhibition is accompanied by a marked decrease in survivin levels and an increase in Caspase 3 cleavage products, indicating enhanced apoptosis. Additionally, in murine xenograft models, Varlitinib (ARRY-334543) shows substantial, dose-dependent tumor growth inhibition in A431-derived tumors when given orally at doses of 25, 50, and 100 mg/kg, twice a day for 21 days.