A Pan-KRAS-Targeted PET Probe for Noninvasive Quantitative Imaging of KRAS Expression

Abstract Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations are key drivers of the initiation and progression of multiple solid tumors. Precise assessment of KRAS mutation status and expression levels is critical for molecular subtyping and targeted therapeutic decision-making. However, pan-KRAS molecular imaging probes capable of noninvasively identifying multiple clinically relevant KRAS mutant subtypes while quantitatively assessing KRAS expressions remain unavailable. In this study, we developed a pan-KRAS-targeted positron emission tomography (PET) probe, [68Ga]Ga-DOTA-pKRASi, based on the pan-KRAS small-molecule inhibitor BI-2493. [68Ga]Ga-DOTA-pKRASi was efficiently prepared with a radiochemical purity exceeding 99%. In vitro cellular uptake studies and micro-PET/CT imaging in tumor-bearing mice demonstrated that the probe specifically targeted multiple clinically relevant KRAS mutant subtypes, including KRAS-G12C, KRAS-G12D, and KRAS-G12V. Compared with the corresponding xenograft models harboring endogenous KRAS mutations, the KRAS-overexpressing models consistently exhibited higher tracer uptake, with the highest tumor uptake observed in the BxPC-3KRAS−G12V model (4.65 ± 0.22 % ID/mL). Competitive blocking reduced tumor uptake by 61.11−68.82%, confirming the excellent in vivo targeting specificity of this probe. Furthermore, the tracer uptake was significantly positively correlated with the mutated KRAS protein content determined by immunohistochemistry in tumor tissues, demonstrating its potential for the quantitative assessment of KRAS expression. Overall, these findings provide a proof-of-concept for pan-KRAS-targeted PET molecular imaging. This imaging strategy enables the noninvasive visualization of multiple clinically relevant KRAS mutant subtypes while allowing quantitative assessment of KRAS expression. This work lays the experimental foundation for the development of companion diagnostics for pan-KRAS-targeted therapies.