This was a massive effort led by Lyla Stanland and Hayden Huggins. Grateful to the hard work of my lab and excellent collaborators Justin Milner, Martin Egli and Albert Bowers. Thanks so much to the reviewers who truly made the paper more robust and challenged us to go in new directions.

(11/11)

Because complete inhibition of mutant KRAS is challenging, we evaluated if dual KRAS blockade with EFTX-G12V (RNAi) and allosteric inhibition (RMC-7977) could improve MAPK inhibition. We found an additive or synergistic effect in several KRAS mutant lines and near complete pERK inhibition.

(10/11)

Using a syngeneic model from Mariano Barbacid’s lab, we observed EFTX-G12V phenocopies anti-tumor effects of tamoxifen-inducible KRAS G12V flox. Consistent w KRAS small molecule inhibitors, we observed highly significant and rapid increases of CD8+ T-cells and many granzyme B+ lymphocytes.

(9/11)

In a KRAS G12V colon model, we observed that prolonged EFTX-G12V treatment led to pEGFR feedback activation, which was largely mitigated by the addition of an anti-EGFR antibody. This indicates the GE11-mediated receptor uptake mechanism for siRNA delivery is compatible with an EGFR Ab.

(8/11)

We found less pEGFR reactivation in colon cancer models with EFTX-G12V, whereas pan-KRAS targeting had robust pEGFR reactivation + increases in tEGFR. We observed decreased pYAP S127 with EFTX-G12V, consistent with YAP-TEAD activation as a likely resistance pathway that emerges.

(7/11)

RNAseq demonstrated mutant-selective silencing results in deep suppression of many cancer hallmarks, and tumor angiogenesis as uniquely suppressed by mutant selective Rx. We observed significant inhibition of microvessel density with EFTX-G12V, and inconsistent effects with pan-KRAS Rx.

(6/11)

EFTX-G12V had significant anti-tumor activity in lung, colon + pancreatic cancer models.

Compared with a more potent pan-KRAS siRNA molecule based on in vitro activity, EFTX-G12V unexpectedly outperformed pan-KRAS inhibition in vivo, prompting us to investigate whether differences exist.

(5/11)

The GE11C-targeting EFTX-G12V siRNA = EFTX-G12V, an EGFR-directed KRAS G12V selective RNAi molecule

Pharmacodynamics demonstrated a single dose of EFTX-G12V resulted in ~80-90% KRAS mRNA + protein silencing in the tumor. We observed minimal to no KRAS WT silencing in those tissues.

(4/11)

For delivery, recent scRNAseq profiling suggested EGFR is a very differentially expressed cancer receptor. GE11 peptide, a EGFR binding peptide without mitogenic activity, covalently linked to siRs could result in receptor-mediated endocytosis and a high efficiency of cancer cell delivery.

(3/11)

To create a KRAS G12V mutant selective siRNA, we utilized sequence optimization and leveraged steric properties of 2OMe modifications to create EFTX-G12V V4 Hi2OMe. Thermodynamics, Ago2 modeling, RNAseq + using isogenic lines confirmed mutant selective KRAS G12V inhibitor + spares KRAS WT.

(2/11)