RIOK2-IN-1 (com 4) is a selective RIOK2 inhibitor with a Kd of 150 nM, though it demonstrates low cellular activity with an IC50 of 14,600 nM. As an atypical kinase, RIOK2's involvement in ribosome maturation and cell cycle progression associates it with various human cancers. The derivative compound CQ211, an enhanced version of RIOK2-IN-1, exhibits robust in vivo and in vitro efficacy. It effectively inhibits the proliferation of MKN-1 and HT-29 cancer cell lines and hinders tumor growth in the MKN-1 mouse xenograft model [1].