Protein arginine methyltransferase-5 (PRMT5) regulates many essential biological processes by catalyzing the symmetric di-methylation of arginine (sDMA) on a variety of histones and non-histone proteins. PRMT5 activity is dysregulated across many hematological and solid tumor and its overexpression is associated with poor patient prognosis. PRMT5 is also often overexpressed in cancer cells. Genetic and pharmacological inactivation have confirmed the importance of PRMT5 activity to the survival of many cancer cells, including hepatocellular carcinoma (HCC) and non-small cell lung cancer (NSCLC). Thus, inhibiting PRTMT5 activity has emerged as an attractive therapeutic strategy in oncology.

We used structure-based drug design to identify novel small molecule inhibitors of PRMT5. ALG-070005, ALG-070043 and ALG-070017 inhibited PRMT5 enzymatic activity in biochemical assays with half-maximal inhibitory concentrations (IC50s) values between 50-150 pM and showed high selectivity against a panel of six other PRMTs. In HepG2 cells (HCC), ALG-070005, ALG-070043 and ALG-070017 potently decreased sDMA levels and inhibited cell proliferation with IC50 values of 1, 3, and 0.2 nM, respectively. These compounds also exhibited similar antiproliferative activity in A549 NSCLC cells. The three novel PRMT5 inhibitors demonstrated favorable ADME/PK profiles with exposure levels in target organs well above IC50 values, even 24 hours after dosing. When dosed orally in mice, these Aligos compounds inhibited tumor growth in HCC and NSCLC xenograft models, with concomitant inhibition of sDMA in the tumor.

In conclusion, we identified and characterized novel potent and selective inhibitors of PRMT5 with antiproliferative effects in various preclinical models of HCC and lung cancers. These drug candidates also have a broad therapeutic potential in oncology beyond HCC and lung cancer.

Citation Format: Francois Gonzalvez, Koen Vandyck, Yannick Debing, Kusum Gupta, Dinah Misner, Qingling Zhang, Jyanwei Liu, Antitsa Stoycheva, Sarah Stevens, Julian Symons, Leonid Beigelman, Pierre Raboisson, Jerome Deval. Discovery of novel potent and selective inhibitors of PRMT5 with anti-tumor activity in hepatocellular carcinoma and lung pre-clinical models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1758.