Description
LOXO-101 (sulfate) is an orally bioavailable, potent, ATP-competitive inhibitor of TRKA, TRKB, and TRKC. LOXO-101 has IC50 values in the low nanomolar range for inhibition of all three TRK family members in binding and cellular assays, with 100x selectivity over other kinases, and has shown acceptable pharmaceutical properties and safety in nonclinical models. The TRK family of neurotrophin receptors, TRKA, TRKB, and TRKC (encoded by NTRK1, NTRK2, and NTRK3 genes, respectively) and their neurotrophin ligands regulate growth, differentiation and survival of neurons.
Uses
Larotrectinib Sulfate is a potent and selective oral ATP-competitive inhibitor of tropomyosin receptor kinases (TRK).
Clinical Use
Larotrectinib sulfate is approved to treat solid tumors with NTRKgene fusion without drug resistance mutation in specific TRK proteins. It is used in adults and children whose cancer has metastasized (spread to other parts of the body) or cannot be removed by surgery and has gotten worse after other treatments or cannot be treated with other therapies. This use is approved under FDA’s Accelerated Approval Program. As a condition of approval, a confirmatory trial(s) must show that larotrectinib sulfate provides a clinical benefit in these patients. Larotrectinib sulfate is also being studied in treating other types of cancer.
in vitro
in previous study, loxo-101 was evaluated for off-target kinase enzyme inhibition against a panel of non-trk kinases at a concentration of 1,000 nm and atp concentrations around the km. results showed that loxo-101 had greater than 50% inhibition for only one non-trk kinase, which was tnk2 with ic50 of 576 nm. moreover, there were neither relevant herg inhibition nor prolonged qt observation [1].
in vivo
animal study found that loxo-101 was able to inhibit in vivo tumor growth. athymic nude mice injected with km12 cells were orally treated with loxo-101 daily for 2 weeks, and dose-dependent tumor inhibition was observed, indicating the ability of loxo-101 to inhibit in-vivo tumor growth [1].
IC 50
low nanomolar range for inhibition of all trk family members
References
[1] doebele rc et al. an oncogenic ntrk fusion in a patient with soft-tissue sarcoma with response to the tropomyosin-related kinase inhibitor loxo-101. cancer discov.2015 oct;5(10):1049-57.
