Degradation of Janus kinases in CRLF2-rearranged acute lymphoblastic leukemia

We evaluated the efficacy of proteolysis-targeting chimeras (PROTACs) directed against Janus kinases. Solving the structure of FDA-approved type I JAK inhibitors ruxolitinib and baricitinib bound to the JAK2 JH1 tyrosine kinase domain enabled the rational design and optimization of Cereblon (CRBN)-directed JAK PROTACs utilizing multiple derivatives of JAK inhibitors, linkers and CRBN-specific molecular glues. The resulting JAK PROTACs were evaluated for target degradation by proteomic approaches, and activity tested in CRLF2-rearranged cell line and xenograft models of ALL.EGA study EGAS00001005180