PRMT5 inhibition by SCR-6920 leads to downregulation of HIF-1a and exhibits synergistic antitumor activity with bevacizumab in ovarian cancer

Protein arginine methyltransferase 5 (PRMT5) is a desirable anticancer target due to its extensive involvement in cellular processes associated with tumor initiation and progression. This study describes an oral PRMT5 selective inhibitor, SCR-6920, with potent inhibitory activity against multiple tumor types. Cryo-EM structure shows that SCR-6920 binds to PRMT5:MEP50 in a substrate-competitive mode with high binding affinity. Notably, RNAseq analysis links vascular endothelial growth factor (VEGF) to PRMT5 and further studies show that SCR-6920 downregulates hypoxia-inducible factor-1a (HIF-1a) expression through the ubiquitin-proteasome degradation pathway, thereby reducing downstream VEGF secretion. Further in vivo efficacy study demonstrates a synergistic effect for SCR-6920 combined with bevacizumab against ovarian cancer. Additionally, SCR-6920 improves the efficacy of clinical first-line ovarian cancer therapies (paclitaxel, docetaxel, doxorubicin, and olaparib). SCR-6920 has progressed into phase 1 clinical trials for solid tumors, and this study paves the way for its future clinical combination exploration in ovarian cancer. Overall design: To determine the oncogenic properties of PRMT5, we performed RNA sequence analysis on A2780 cells that were treated with either DMSO or SCR-6920 for 48 hours.