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LOXO-101 is a small molecule that was designed to block the ATP binding site of the TRK family of receptors, with 2 to 20 nM cellular potency against the TRKA, TRKB, and TRKC kinases.
in vitro: LOXO-101 is an orally administered inhibitor of the TRK kinase and is highly selective only for the TRK family of receptors. LOXO-101 is evaluated for off-target kinase enzyme inhibition against a panel of 226 non-TRK kinases at a compound concentration of 1,000 nM and ATP concentrations near the Km for each enzyme. In the panel, LOXO-101 demonstrates greater than 50% inhibition for only one non-TRK kinase (TNK2 IC50, 576 nM). Measurement of proliferation following treatment with LOXO-101 demonstrates a dose-dependent inhibition of cell proliferation in all three cell lines. The IC50 is less than 100 nM for CUTO-3.29 and less than 10 nM for KM12 and MO-91, consistent with the known potency of this drug for the TRK kinase family. LOXO-101 demonstrates potent and highly-selective inhibition of TRKA, TRKB, and TRKC over other kinase- and non-kinase targets. LOXO-101 is a potent, ATP-competitive TRK inhibitor with IC50s in low nanomolar range for inhibition of all TRK family members in binding and cellular assays, with 100x selectivity over other kinases.
in vivo: Athymic nude mice injected with KM12 cells are treated with LOXO-101 orally daily for 2 weeks. Dose-dependent tumor inhibition is observed, demonstrating the ability of this selective compound to inhibit tumor growth in vivo. |
