Abstract 4495: Structure-based screening for potential ROR1 inhibitors and their potential as antitumor agents in pancreatic cancer cells
Authors: Singh Indrakant Kumar , Gupta Shradheya RR , Mittal Pooja , Soni Shivani , Lo Jae Ho , Battaglin Francesca , Yang Yan , Torres-Gonzalez Lesly , Algaze Sandra , Jayachandran Priya , Ashouri Karam , Wong Alexandra , Zhang Wu , Millstein Joshua , Lenz Heinz Josef 
Published: March 2024

Background: The identification of novel compounds that specifically target cancer cells while sparing normal tissues is crucial. The orphan tyrosine kinase-like receptor 1 (ROR1) is one such target expressed exclusively in various human malignancies, including pancreatic cancer, but not in normal adult tissues. Inhibiting ROR1 signaling shows promise in halting pancreatic cancer cell proliferation and invasion. In this study, lead compounds CSF1R-IN-1 and MCULE-8715589337 were found as potential inhibitors of the ROR1 and were further evaluated for its potential effect on pancreatic cancer cell viability.

Method: We curated a compound library of 6 million from PubChem, 2 million lead-like compounds from ZINC15, and 2 million compounds from diverse vendors. Employing Glide’s HTVS followed by XP, we refined the selection based on docking scores lower than the reference molecule, Ponatinib. Compounds were shortlisted by pre-simulation MMGBSA calculations with Schrödinger Prime MM-GBSA module, focusing on compounds with energies below -100 kcal/mol. Then we performed MD simulation for 100ns. Post-simulation MMGBSA on the last 1 ns of simulation assessed change in ligands’ binding energies. The selected leads underwent further validation utilizing two pancreatic cancer cell lines, MiaPaCa-2 and PANC-1. Half-maximal inhibitory concentration (IC50) was assessed using MTS cell viability assay.

Result: Comparing pre- and post-simulation MMGBSA energies, the reference compound showed increased, while CSF1R-IN-1 and MCULE-8715589337 exhibited decreased energies. The reference ligand's RMSD showed stability with fluctuations of 3 to 3.5 Å, whereas CSF1R-IN-1 and MCULE-8715589337 had stable and lower RMSD values (approximately 3 Å and 2.4 Å). Test compounds, CSF1R-IN-1 and MCULE-8715589337 showed better molecular interactions with ROR1 compared to reference. The reference compound formed hydrogen bonds with ILE555 and ASP633, along with pi-pi stacking with PHE552. CSF1R-IN-1 forms a hydrogen bond with ILE555 and ASP633, pi-pi stacking with PHE552, and interaction with SER632 through a water bridge. Additionally, compound MCULE-8715589337 forms hydrogen bonds with ASP633, SER632, LYS506, and GLU523. CSF1R-IN-1 notably inhibited proliferation in MiaPaCa-2 cells (IC50: 1.29 μM) while no efficacy in PANC-1 cells (IC50: 78.41 μM). MCULE-8715589337 showed relatively similar IC50 values of 39.06 μM and 37.73 μM in MiaPaCa-2 and PANC-1 cells, respectively.

Conclusion: The reduction in MMGBSA energies, low RMSD values, and a higher number of interactions highlight the better characteristics of both compounds compared to the reference. Our findings show CSF1R-IN-1 and MCULE-8715589337 have efficacy in pancreatic cancer cells, but further studies are required to validate and to understand the mechanism of action.

Citation Format: Indrakant Kumar Singh, Shradheya RR Gupta, Pooja Mittal, Shivani Soni, Jae Ho Lo, Francesca Battaglin, Yan Yang, Lesly Torres-Gonzalez, Sandra Algaze, Priya Jayachandran, Karam Ashouri, Alexandra Wong, Wu Zhang, Joshua Millstein, Heinz Josef Lenz. Structure-based screening for potential ROR1 inhibitors and their potential as antitumor agents in pancreatic cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4495.