Neuroblastoma xenograft mice: NOD/SCID/IL2R-gamma immunocompromised mice were injected s.c. with SK-N-SH neuroblastoma cells and palpable tumors were allowed to develop. Mice were then dosed by oral gavage twice daily with either vehicle alone or 100 mg/kg AZ-23. Mice were sacrificed and tumors were harvested 12 days after the start of treatment or when tumor growth reached institutional limits.

AZ-23 potently and selectively inhibits Trk phosphorylation in cells. The cellular potency of AZ-23 against Trk phosphorylation was determined using a phospho-TrkA ELISA assay. A stably transfected human MCF10A cell line was engineered to express a constitutively active form of human TrkA containing a 75-amino-acid extracellular deletion (MCF10A-TrkA-Δ) originally isolated from an AML patient. A cellular EC50 value of 1.2 ± 0.7 nmol/L was determined for AZ-23, a result corroborated through immunoblotting for phosphorylated TrkA protein.