Design, synthesis and biological evaluation of 2-aminopyrimidine-based LSD1 inhibitors

AZD9291, with excellent pharmaceutical properties, has been reported to have certain LSD1 inhibitory activity. Therefore, we carried out structural optimization based on the AZD9291 skeleton to increase the LSD1 inhibitory potential of the compound. Then, a series of 2-aminopyrimidine derivatives were designed and synthesized as LSD1 inhibitors, and their structure-activity relationships were studied. The most promising compound, X43, with an IC₅₀ of 0.89 μM showed remarkable LSD1 selectivity not only to EGFR^wt (>100-fold) but also to MAO-A/B (>50-fold). Further studies showed that X43 inhibited LSD1 activity and induced the apoptosis of A549 cells in a dose-dependent manner. Meanwhile, compound X43 showed a superior ability to inhibit the proliferation of A549 and THP-1 cells, with IC₅₀ values of 1.62 μM and 1.21 μM, respectively. Then, analyses of the stability of human liver microsomes, CYP inhibition and in vivo pharmacokinetics in rats showed that X43 had favorable profiles in vitro and in vivo and the potential for further study. Our findings suggested that a 2-aminopyrimidine-based LSD1 inhibitor deserves further investigation as a treatment for LSD1-overexpressing cancer.