Abstract 950: In vivo efficacy and pharmacodynamic modulation of JNJ-64619178, a selective PRMT5 inhibitor, in human lung and hematologic preclinical models

Protein arginine methyltransferase 5 (PRMT5), a type II methyltransferase, is responsible for symmetric arginine di-methylation of multiple cellular proteins involved in the regulation of cellular transcription. PRMT5 is involved in cellular processes such as survival, proliferation, and apoptosis, and an elevated tumor PRMT5 protein level has recently been correlated with poor survival of cancer patients. JNJ-64619178, a selective PRMT5 inhibitor, showed inhibition of cellular growth in several cell lines representing multiple cancer histologies in vitro. From this, a broad selection of xenograft models was chosen to demonstrate potent anti-tumor efficacy. Xenograft models representing small cell lung cancer (SCLC), non-small cell lung cancer (NSCLC), acute myeloid leukemia (AML), and non-Hodgkin lymphoma were chosen to demonstrate anti-tumor efficacy. Biologically significant tumor growth inhibition up to 99% was observed in both solid and hematological xenograft models, including an aggressive disseminated model of AML, with oral doses of 1 to 10 mg/kg, once daily. Importantly, continued inhibition of tumor growth was observed for several weeks following dosing cessation. Dosing of JNJ-64619178 results in inhibition of Sym-Arg di-methylation of SMD1/3 proteins, core components of the spliceosome in the tumor, and general Sym-Arg di-methylation of serum proteins. These serve as pharmacodynamic markers of PRMT5 inhibition in xenograft models. Potent and prolonged inhibition of SMD1/3 di-methylation was observed in the SCLC model, during and after the dosing period. This has led to the exploration of alternative dosing regimens preclinically. PRMT5 inhibitor JNJ-64619178 is currently being investigated in a Phase I clinical trial, based on its high selectivity and potency, favorable pharmacokinetics and safety properties, and strong preclinical efficacy and pharmacodynamic data. Citation Format: Hillary J. Millar, Dirk Brehmer, Tinne Verhulst, Nahor Haddish-Berhane, Tony Greway, Dana Gaffney, An Boeckx, Erika Van Heerde, Thomas Nys, Joseph Portale, Ulrike Philippar, Tongfei Wu, Sylvie Laquerre, Kathryn Packman. In vivo efficacy and pharmacodynamic modulation of JNJ-64619178, a selective PRMT5 inhibitor, in human lung and hematologic preclinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 950.