Larotrectinib (LOXO-101)

Biological Activity

In vitro: Larotrectinib (LOXO-101) was 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. LOXO-101 demonstrated greater than 50% inhibition for only one non-TRK kinase (TNK2 IC50 = 576 nM).

In vivo: A single dose (30 mg/kg) of LOXO-101 reduced tyrosine phosphorylation of TRKA and downstream signal transduction (pERK) in the tumor >80%. LOXO-101 was well tolerated up to 200 mg/kg/day for 14 d in this model.

Product Citations

• 

  Br J Cancer. 2023 Mar 23.

  Functional genomics of human clear cell sarcoma: genomic, transcriptomic and chemical biology landscape for clear cell sarcoma
  Larotrectinib (LOXO-101) purchased from AbMole

• 

  Clin Transl Med. 2022 Jul;12(7):e961.

  Functional genomic analysis of epithelioid sarcoma reveals distinct proximal and distal subtype biology
  Larotrectinib (LOXO-101) purchased from AbMole

Customer Product Validations & Biological Datas

	Source	Cancer Discov (2015). Figure 1. LOXO-101
	Method	MTS assay
	Cell Lines	CUTO-3.29 cells
	Concentrations	100 nM
	Incubation Time	2 h
	Results	pAKT was not inhibited in the CUTO-3.29 cells by LOXO-101 suggesting that TRK signaling is not AKT-dependent in this tumor.

Protocol (for reference only)

Cell Experiment
Cell lines	KM12 cells
Preparation method	Dose-dependent inhibition with LOXO-101 is demonstrated in three cancer cell line models of oncogenic TRK.
Concentrations	100 nM
Incubation time	24h

Animal Experiment
Animal models	Athymic nude mice
Formulation
Dosages	60 mg/kg
Administration	oral gavage

Chemical Information

Molecular Weight	428.44
Formula	C21H22F2N6O2
CAS Number	1223403-58-4
Solubility (25°C)	4 mg/mL in DMSO
Storage	Powder          -20°C   3 years ;  4°C   2 years In solvent       -80°C   6 months ;  -20°C   1 month

Conversion of different model animals based on BSA (PMID: 27057123)

Species	Mouse	Rat	Rabbit	Guinea pig	Hamster	Dog
Weight (kg)	0.02	0.15	1.8	0.4	0.08	10
Body Surface Area (m2)	0.007	0.025	0.15	0.05	0.02	0.5
Km factor	3	6	12	8	5	20

Animal A (mg/kg) = Animal B (mg/kg) multiplied by	Animal B Km
	Animal A Km

For example, to modify the dose of Compound A used for a mouse (20 mg/kg) to a dose based on the BSA for a rat, multiply 20 mg/kg by the K_m factor for a mouse and then divide by the K_m factor for a rat. This calculation results in a rat equivalent dose for Compound A of 10 mg/kg.

References

[1] Nagasubramanian R, et al. Pediatr Blood Cancer. Infantile Fibrosarcoma With NTRK3-ETV6 Fusion Successfully Treated With the Tropomyosin-Related Kinase Inhibitor LOXO-101.

[2] Doebele RC, et al. Cancer Discov. An Oncogenic NTRK Fusion in a Patient with Soft-Tissue Sarcoma with Response to the Tropomyosin-Related Kinase Inhibitor LOXO-101.