MRTX1133 is an exceptionally potent and selective KRASG12D inhibitor with high affinity (<2nM).^[1]

In vitro, in the AGS cell line, MRTX1133 inhibited ERK phosphorylation with an IC₅₀of 2 nM. In the meanwhile, MRTX1133 was against the same cell line with an IC₅₀of 6 nM in a 2D viability assay.^[1]In vitro efficacy test, in KRASG12D–mutant HPAC Cells, it indicated that treatment with 0.05 nM - 300 nM MRTX1133 has a dose-dependent pERK, pS6 & DUSP6 modulation.^[2]

In vivo experiment it shown that treatment with 30 mg/kg of MRTX1133 intraperitoneally in CD-1 mice caused the sustained plasma exposure exceeding the free-fraction-adjusted pERK IC₅₀value in the KRASG12D mutant Panc 04.03 cell line for approximately 8 h. And in the Panc 04.03 xenograft tumor model, it suggested that MRTX1133 (3-30 mg/kg, i.p.) has dose-dependent antitumor activity with 94% growth inhibition observed at 3 mg/kg BID (IP) and tumor regressions of –62% and –73% observed at 10 and 30 mg/kg BID (IP), respectively.^[1]

References:
[1].Wang X, Allen S, et al. Identification of MRTX1133, a Noncovalent, Potent, and Selective KRASG12D Inhibitor. J Med Chem. 2022 Feb 24;65(4):3123-3133.
[2].Swiatnicki M, Engel L, Shrestha R, Alves J, Goueli SA, Zegzouti H. Profiling oncogenic KRAS mutant drugs with a cell-based Lumit p-ERK immunoassay. SLAS Discov. 2022 Jun;27(4):249-257.