RNA-Seq identifies alternative splicing of CRBN induced by ILF3 KO

We present a first-in-class GSPT1-selective CELMoD, CC-90009, which is currently in a phase 1 clinical trial for the treatment of relapsed or refractory (R/R) AML (CC-90009-AML-001; NCT02848001). Biochemical, structural and molecular characterization supports that CC-90009 coopts the CUL4-DDB1-CRBN-RBX1 (CRL4-CRBN) E3 ubiquitin ligase complex to selectively target GSPT1 for ubiquitination and proteasomal degradation, culminating in rapid induction of apoptosis and growth inhibition in AML cell lines and patient leukemic blasts. Knockout of ILF2/ILF3 decreased the production of full-length CRBN transcript via modulating CRBN mRNA alternative splicing, leading to significant downregulation of cereblon expression and hence diminished response to CC-90009. Overall design: mRNA profiling on U937-Cas9 cells expressing sgNT or sgILF3 followed by differential exon usage analysis to predict alternative splicing