MTI-31 (LXI-15029) is a potent, orally active, and highly selective inhibitor of mTORC1 and mTORC2, exhibiting a Kd of 0.20 nM for mTOR and >5,000-fold selectivity over PIK3CA, PIK3CB, and PIK3G in binding assays, with an IC50 of 39 nM for mTOR in a LANCE assay of mTOR substrate phosphorylation with 100 μM ATP [1].

mTOR:39 nM (ATP=100 μM), mTOR:0.2 nM(Kd)

MTI-31 (0.01-100 μM) elicits a potent and more substantial inhibition of cell growth than that of Rapamycin[1]. Treatment with MTI-31 for 6 h demonstrates a dose-dependent inhibition of both the mTORC1 substrates P-S6K1(T389), P-S6(S235/6), P-4EBP1(T70) and mTORC2 substrate P-AKT(S473), achieving 50% inhibition at ≤0.12 μM in three representative tumor cell lines harboring mTOR pathway dysregulation (786-O renal, U87MG glioma and MDA-MB-453 breast)[1]. MTI-31-induced apoptosis requires mTORC2-regulated Bim- and GSK3 activity[1].

MTI-31(5-40 mg/kg; orally) is efficacious in several tumor models harboring HER2+/PIK3CAmut and/or PTEN-deficiency exemplified by MDA-MB-453 and 786-O[1]. Treatment of tumor bearing nude mice with orally administered MTI-31 inhibits growth of H1975 tumors (25 mg/kg/d; orally) or U87MG tumors (30 mg/kg/d; orally)[2].