An orally available inhibitor of protein arginine N-methyltransferase 1 (PRMT1; Histone-arginine N-methyltransferase PRMT1; Interferon receptor 1-bound protein 4) with potential antineoplastic activity. Upon administration, GSK3368715 inhibits monomethylation and asymmetric dimethylation of arginine-bearing substrates, including histones, estrogen receptors, RNA-binding proteins, and numerous non-histone substrates catalyzed by PRMT1. This may inhibit tumor cell proliferation, migration, and invasion that is potentially driven by PRMT1 overexpression or dysregulation. PRMT1-mediated methylation plays a key role in the modulation of protein function, gene expression and cellular signaling. Dysregulation and overexpression of PRMT1 has been associated with a number of solid and hematopoietic cancers.