Abstract 4859: JNJ-64619178, a selective and pseudo-irreversible PRMT5 inhibitor with potentin vitroandin vivoactivity, demonstrated in several lung cancer models

PRMT5 is a type II methyltransferase that symmetrically di-methylates arginine residues on proteins involved in signal transduction and cellular transcription. For example, PRMT5 acts as the enzymatic machinery of the methylosome complex, crucial for spliceosome assembly and activity. Although not frequently mutated or amplified in tumors, an elevated PRMT5 protein level that leads to higher methylosome activity and promotes epithelial–mesenchymal transition, has recently been correlated with a poor survival of cancer patients. The PRMT5 inhibitor JNJ-64619178 has been selected as a clinical candidate based on its high selectivity and potency, paired with favorable oral pharmacokinetics and safety properties. JNJ-64619178 binds simultaneously to the SAM- and protein substrate- binding pockets of the PRMT5/MEP50 complex with a pseudo-irreversible mode-of-action. Chemical proteomics, methylomics and RNA-sequencing analyses of PRMT5 inhibitor treated cell line samples support the current biological understanding of PRMT5 as a regulator of alternative splicing events. JNJ-64619178 showed potent and broad inhibition of cellular growth, observed in several cell line panels that represent diverse cancer histologies. Ongoing investigations will explore the potential synthetic lethal correlation between PRMT5 inhibition and cancer driver pathways, including those addicted to altered splicing. Oral administration of JNJ-64619178 resulted in efficient inhibition of di-methylation of SMD1/3 proteins, components of the splicing machinery and direct substrates of the methylosome, in several human NSCLC and SCLC cancer mouse xenograft models. JNJ-64619178 demonstrated dose-dependent tumor growth inhibition and regression in several human NSCLC and SCLC cancer mouse xenograft models with sustained blockage of tumor re-growth after dosing cessation. In summary, JNJ-64619178 has a favorable pre-clinical profile supporting clinical testing in patients with lung cancer and other malignancies. Citation Format: Tongfei Wu, Hillary Millar, Dana Gaffney, Lijs Beke, Geert Mannens, Petra Vinken, Ivan Sommers, Jan-Willem Thuring, Weimei Sun, Christopher Moy, Vineet Pande, Junguo Zhou, Nahor Haddish-Berhane, Mark Salvati, Sylvie Laquerre, Matthew V. Lorenzi, Dirk Brehmer. JNJ-64619178, a selective and pseudo-irreversible PRMT5 inhibitor with potent in vitro and in vivo activity, demonstrated in several lung cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4859.