Narazaciclib (HX301 or ON123300) is an investigational multi-kinase inhibitor (TKi) being developed for treating different cancers due to its broad potency against CSF1R, FLT3, CDK4/6, ARK5, etc. It demonstrated robust antitumor activities in experimental cancer models in vitro and in vivo presumably due to one or more the above-mentioned potencies in these model systems22–25. This evidence concerns the gene CDK4 and cancer.