KRAS G12D

KRAS G12D is a point mutation in the KRAS gene that substitutes aspartate for Glycine at codon 12. Glycine-12 sits in the P-loop that cradles the γ-phosphate of bound GTP, and the larger aspartate side chain obstructs the arginine finger that GTPase-activating proteins insert to catalyze hydrolysis. The mutant therefore retains residual intrinsic GTPase activity but is effectively deaf to GAP stimulation, so it accumulates in the GTP-bound state and signals continuously through the RAF–MEK–ERK cascade, the PI3K/AKT/mTOR pathway, and RAL guanine nucleotide exchange factors, driving proliferation and survival independently of upstream receptor input.

It is among the most prevalent oncogenic drivers in human Cancer. In pancreatic ductal adenocarcinoma, where KRAS is mutated in over 90% of Tumors, G12D is the single most common variant at roughly 35–45% of cases; it is also frequent in colorectal cancer and appears in lung adenocarcinoma, though there KRAS G12C predominates.

G12D was long considered undruggable, and the reason is specific rather than general: picomolar affinity for GTP rules out competitive nucleotide inhibitors, and the covalent strategy that yielded the first approved KRAS drugs depends on a reactive cysteine that G12C provides and G12D does not. Progress has come from non-covalent inhibitors that exploit the aspartate itself, from RAS(ON) compounds that act on the active GTP-bound state through a cyclophilin A complex rather than on the inactive state, and from targeted protein degradation. In parallel, the mutant peptide is being pursued as a public neoantigen through T cell receptor–engineered cell Therapy and vaccines, since a recurrent single substitution presented on a shared HLA allele is the same target for many patients. Adaptive reactivation of ERK Signaling is the recurring obstacle to all of the direct approaches, which is why combinations with upstream or downstream inhibitors are under active study.