Larotrectinib (LOXO-101) is an orally administered inhibitor of the TRK kinase, demonstrating high selectivity exclusively for the TRK family of receptors (IC50s = 2-20 nM).

Trk:2-20 nM

In vivo, Larotrectinib?(60 and 200 mg/kg) reduces tumor growth in a KM12 mouse xenograft model[1].

Mice were maintained under aseptic conditions.?The care and treatment of experimental animals was in accordance with institutional guidelines.?5 × 10^5 KM12 cells were injected subcutaneously into the dorsal flank area of the mice.?Tumor volume was monitored by direct measurement with calipers and calculated by the formula: length × (width^2)/2.?Following the establishment of tumor and when the tumor size was between 150–200 mm^2, mice were randomly selected to receive diluent, 60 mg/kg/dose or 200 mg/kg/dose of Larotrectinib(LOXO-101).?LOXO-101 was administered by oral gavage once daily for 14 days.?After the last dose, tissue and blood were collected at 3, 6 and 24 hours post-treatment[1].