Altered PI3K and ERK/MAPK Signaling in KRASG12R-Driven Pancreatic Cancer Presents Opportunities for Precision Therapy.

Pancreatic ductal adenocarcinoma (PDAC) remains among the deadliest malignancies with near-universal KRAS mutation. Although KRASG12D and KRASG12V are predominant, KRASG12R is also prevalent in PDAC yet rare in other KRAS-driven cancers such as lung and colorectal adenocarcinoma, suggesting pancreas-specific selective pressures. Unlike other KRAS mutants, KRASG12R fails to productively engage key nodes that amplify oncogenic output including wild-type (WT) RAS and PI3K signaling. Furthermore, KRASG12R-mutant PDAC has been shown to be more sensitive to MAPK/ERK inhibition compared with other KRAS-mutant tumors. Three complementary studies now clarify how KRASG12R promotes PDAC growth and why this genotype may carry distinct therapeutic vulnerabilities. First, Burge and colleagues identify KRASG12R-independent PI3K maintenance driven by PTEN oxidation and broad PI3K isoform utilization, with nutrient limitation further enhancing PTEN oxidation. Second, in a separate study, Burge and colleagues develop KRASG12R mouse models and show that KRASG12R tumors exhibit reduced ERK/MAPK transcription, collagen deposition, and metastasis. Third, Kamgar and colleagues demonstrate an impaired cross-talk of KRASG12R with WT RAS and stoichiometric dependencies that help explain heightened MEK inhibitor sensitivity, supported by clinical trials combining MEK and autophagy inhibition. Together, these articles reposition KRASG12R PDAC as a biologically constrained yet therapeutically exploitable subtype. See related article by Burge et al., p. 1854 See related article by Burge et al., p. 1868 See related article by Kamgar et al., p. 2042.