1000V Poster Online - Virtual Posters
Wednesday April 06, 4:00 PM - 7:00 PM

Authors:
Kimberly Stephens ¹; Jared Gatto ¹; Jianping Hu ¹; Cèline Guichard ²; Rupa Mirmira ¹; Tirtha Das ¹; Husnu Kaniskan ¹; Jian Jin ¹; Ross Cagan ³; Bruce Gelb ¹

Affiliations:
1) Mount Sinai School of Medicine; 2) Aix Marseille University; 3) University of Glasgow

Keywords:
f. drug discovery; f. drug discovery

Introduction: RASopathies are pleiomorphic genetic traits, predominantly resulting from gain of function in RAS/MAPK signaling. Hypertrophic cardiomyopathy (HCM) is a leading therapeutic target because of its association with early mortality in affected infants. MEK inhibitors have shown promise in pre-clinical studies and compassionate-usage in patients but are not curative, have dermatological side effects and are not uniformly efficacious. Developing RASopathy therapeutics that can be administered long-term while allowing homeostatic levels of RAS signaling is challenging. To address that, we used phenotype-driven, whole-organism chemical screening in Drosophila RASopathy models to drive therapeutic discovery.
Hypothesis: Using a fruit fly-based platform, we can identify novel small molecular therapeutics for RASopathies.
Methods: We generated transgenic Drosophila bearing pathogenic alleles associated with HCM and screened a chemical library for lead compounds based on rescuing lethality. We chemically evolved our best hit, M1, iteratively and assessed rescue efficacy. We assessed putative targets using similarity ensemble analysis (SEA).
Results: The parent M1 compound showed weak efficacy toward transgenic RAF1-S257L flies with 10 uM dosing in fly media. JH107-7 was the best M1 derivative for the RAF1 model, achieving 50% rescue with 1 uM dosing. Testing in other RASopathy fly models revealed nearly complete rescue in flies expressing PTPN11-N308D but not BRAF-W531C. M1 derivative JH93-178T rescued 45% of BRAF flies but was not effective for other fly models. To assess potential as cancer therapeutics, we tested our M1 derivatives against two RAS-driven colon cancer fly models for which no single drug has shown efficacy. For JH107-7 and JH93-178T, we nearly matched efficacy of combination chemotherapy with trametinib and zoledronic acid, a drug combination effective in flies and a patient. JH107-7’s top 10 target predictions included RAF1, BRAF and mTOR.
Conclusion: Two M1-logs show efficacy for RASopathies and cancer in transgenic fly models with likely in-animal dosing of 5-50 nM (1/200 of concentration in food). Preliminary data with human RASopathy-mutant induced pluripotent stem cell-based HCM modeling suggest efficacy in rescuing cellular hypertrophy. We are currently assessing M1 derivatives’ impact on signaling pathways.