Identification of Thieno[3,2-d]pyrimidine derivatives as potent and selective Janus Kinase 1 inhibitors

Being a primary driver in oncogenic activations of JAK-STAT signaling pathway, Janus Kinase 1 (JAK1) stands out as a promising target in anti-cancer drug discovery. We employed a scaffold morphing strategy to design and synthesize thieno[3,2-d]pyrimidine derivatives, which led to identification of 24 as a potent and highly selective JAK1 inhibitor. Kinome-wide selectivity profiling reveals that 24 exhibits a high degree of selectivity for JAK1 among the 370 kinases tested. SAR study demonstrates that both 25 and 46, improved derivatives of 24, possess higher selectivity towards JAK1 over JAK2 and JAK3 compared to AZD4205 (9). It is of note that 46 has 4-fold higher enzymatic activity against JAK1 (IC₅₀ = 0.022 μM) relative to 9. Moreover, both 25 and 46 demonstrate over 5-fold enhancement in anti-proliferative activities on NSCLC cells with regard to 9, accompanied by significant inhibition of JAK1 signaling. Compared with 9, derivative 24, 25, and 46 induce more strongly apoptosis, cell cycle arrest, and reduction of colony formation on NSCLC cells. Our findings offer valuable insights into the design of novel selective JAK1 inhibitors.