Abstract 3233: EP102: Pharmacological Inhibition of METTL3 causes tumor growth inhibition and prolongs survival in preclinical models of NSCLC, ovarian and squamous cell carcinoma

Abstract METTL3 is the RNA methyltransferase predominantly responsible for the addition of N-6-methyladenosine (m6A), the most abundant epigenetic modification to mRNA. The prevalence of m6A and the activity and expression of METTL3 have been linked to the appearance and progression of numerous hematological and solid tumor cancers. EPICS has discovered and optimized small molecule inhibitors of METTL3 (“M3i”). The aim of the current study is to evaluate the efficacy of M3i in various CDX mouse tumor models. M3i compound potency was evaluated in vitro by measuring enzymatic inhibition of METTL3/14 by scintillation proximity assay (IC50 = 2 nM). The anti-proliferative effects of M3i were measured in cell viability assays following a 72h treatment of A549 (NSCLC, IC50 = 190 nM), SKOV3 (ovarian, IC50 = 9 nM) and FaDu (hypopharyngeal squamous cell carcinoma, IC50 = 24 nM) cells. Complementary data in all three cell lines demonstrates a clear concentration-response for a target engagement biomarker (m6A; IC50 = 2-8 nM, across cell lines) as well as M3i-induced changes in biomarkers of oncogenic drivers. M3i (30 mg/kg, IP, QD) was tested in vivo in mouse models using FaDu (subcutaneous implant) in addition to A549 and SKOV3 (both orthotopic implants) ; all animal models were performed by LabCorp (MI, USA). Daily M3i treatment significantly prolonged survival in all three disease models consistent with efficacy on tumor growth inhibition as measured by imaging (A549, SKOV3) or direct measurement of tumor volume in the case of subcutaneous implant (FaDu). M3i has previously been shown to be effective in mouse CDX and PDX models of AML. The current results extend the application of METTL3 inhibitors to include the treatment of various types of solid tumors. The efficacy of M3i as a single-agent on tumor growth inhibition and survival advances the validation of METTL3 as a cancer target and provides additional evidence for the applicability of mRNA epigenetic mechanisms to the treatment of solid tumors. Citation Format: Graeme Fraser, Catherine Sorlet, Nicolas Parmentier, Elodie Brunel, Christian Coremans, Sarah Rorive, Anne-France Hartiel, Killian Oukoloff, Guillaume Dutheuil. EP102: Pharmacological Inhibition of METTL3 causes tumor growth inhibition and prolongs survival in preclinical models of NSCLC, ovarian and squamous cell carcinoma 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 (6Suppl): Abstract nr 3233.