KRAS is the most frequently mutated oncogene and increased development efforts targeting KRAS mutations have yielded recent FDA approvals of two KRAS G12C inhibitors. However, for some indications, there are other KRAS mutations more common than G12C. For Pancreatic ductal adenocarcinoma (comprising more than 90% of pancreatic cancer cases), 94% harbor KRAS mutations, where G12D mutations account for around 45% while G12C mutations are rare (1%). Hence, there is a need to develop methods to target a broader range of KRAS mutations. Beyond direct gene mutation, activation of oncogenic KRAS and downstream MAPK signaling through other genomic alterations may benefit from KRAS-specific therapeutic strategies, especially combination therapy. We have developed a platform, Optim.AI™, that rationally converges upon optimal drug combinations within a defined drug search space, without any prior knowledge of the background of the models.  In this study, we utilized the platform to identify efficacious drug combinations that contain a histone deacetylase 4/6 inhibitor, KYAN-001 in the context of KRAS mutations. 7 cell lines (6 prostate and pancreatic cancer with normal, epithelial THLE-2 cell line) were evaluated with Optim.AI. The cancer cells and THLE-2 were seeded into 384-well plates and treated with 155 different combinations consisting of indication-specific drugs the following day. Post-drug treatment cell viability was used for Optim.AI™ analysis, which maps experimental data points to a second-order quadratic function to predict and rank cancer cell killing efficacies for all other permutations of drug combinations. In androgen resistant prostate cancer, Optim.AI identified synergistic interaction between KYAN-001 and a MEK inhibitor. With MEK being downstream of the KRAS pathway, we wanted to evaluate the efficacy of this combination on pancreatic cancer. Interestingly, this combination was demonstrated to be top ranked against PANC-1 and AsPC-1 cell lines, both harboring G12D KRAS mutation, as compared to a cell line with wild-type KRAS, BxPC-3. This was further validated via half-maximal inhibitory curves (IC50), where synergism was also observed for the combination on AsPC-1, but not BxPC-3. KYAN-001 was also shown to exhibit monotherapy sensitivity against pancreatic cancer patient-derived organoids (PDOs), with a mean of 4 µM. This study has successfully demonstrated the ability of Optim.AI™ to identify novel, optimal drug combinations for both prostate and pancreatic cancers, without any prior background knowledge on these cell lines. With MEK being downstream of the KRAS pathway and 94% of those diagnosed with pancreatic cancer have KRAS mutations, the differential sensitivities of this combination across the cell lines presents the utility of the platform in precision medicine, especially for undruggable targets like KRAS. With promising and demonstrated monotherapy efficacy of KYAN-001 on PDOs, further experiments could be done to evaluate the clinical relevance of both KYAN-001 and MEK inhibition on other relevant ex vivo models.

Citation Format: Masturah Mohd Abdul Rashid, Lisa Chow, Edward Kai-Hua Chow. Identification of therapeutic drug combinations targeting KRAS [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A127.