Selitrectinib (LOXO-195) is a potent and selective inhibitor of the receptor tyrosine kinases(TRK)( TrkA and TrkC with IC50s of 0.6 and <2.5 nM, respectively).

TrkA:0.6 nM , TrkC:<2.5 nM

Each cell line (2–5×10e6 cells) was injected subcutaneously into female nu/nu NCr mice age 7–9 weeks and allowed to grow to ~100–200 mm3 (efficacy) or ~ 500mm3 (PK-PD) prior to randomization by tumor size and treatment with each inhibitor by oral gavage.?For PK-PD analysis, animals were dosed for 3 days, followed by euthanasia, excision of tumors and collection of plasma.?Phospho-TRK levels in tumor lysates were determined by ELISA assay, while plasma inhibitor levels were determined by LC-MS/MS.?For efficacy analysis, animals were dosed by oral gavage, and body weight and tumor size were monitored at regular intervals.