MRTX1133 is a KRAS G12D inhibitor (KD=0.2 pM) that is potent, selective, and non-covalent. MRTX1133 exhibits inhibitory activity against KRAS G12D-mutated tumors, but not against KRAS wild-type tumors.

METHODS: Human gastric cancer cells AGS (KRASG12D) and MKN1 (KRASWT) were treated with MRTX1133 (0-3 μM) for 72 h, and cell viability was measured by CTG method in 2D culture.
RESULTS: The IC50 of MRTX1133 on AGS and MKN1 cells was 6 nM and >3000 nM, respectively. [1]
METHODS: Human gastric cancer cells AGS (KRASG12D) were treated with MRTX1133 (0-10 μM) for 3-72 h, and the expression levels of target proteins were detected by In-Cell Western method.
RESULTS: MRTX1133 inhibited the p-ERK level of AGS with an IC50 of 2 nM. [1]
METHODS: Human pancreatic cancer cells SUIT2 (KRASG12D) were treated with MRTX1133 (60 nmol/L) for 24 h, and the expression levels of target proteins were detected by Western Blot.
RESULTS: SUIT2 cells treated with MRTX1133 showed a significant decrease in pMEK1/2, a partial decrease in pERK1/2, and an initial decrease in pAKT followed by a recovery at a later time point. The levels of pEGFR and pHER2 decreased and recovered at 72 h. [2]

METHODS: To test the antitumor activity in vivo, MRTX1133 (3-30 mg/kg, 10% Captisol in 50 mM citrate buffer pH 5.0) was intraperitoneally injected into nude-Foxn1nu mice bearing human pancreatic adenocarcinoma tumor Panc 04.03 twice daily for seven weeks.
RESULTS: MRTX1133 exhibited dose-dependent antitumor activity, with 94% tumor growth inhibition observed at the 3 mg/kg group. Tumor regression of -62% and -73% was observed in the 10 mg/kg and 30 mg/kg groups, respectively. [1]
METHODS: To assay antitumor activity in vivo, MRTX1133 (0.5 mg/kg in 12.5% Cremophor+12.5% ethanol+75%, orally once daily) and Cetuximab (50 mg/kg, intraperitoneally once weekly) were administered to BALB/c nude mice harboring human colorectal tumors, LS531 or CACO-2 for twenty-one days.
RESULTS: MRTX1133 significantly inhibited tumorigenesis in both in vivo models. The anti-tumor effect was further enhanced when MRTX1133 was combined with Cetuximab. [3]