Correlation of IMiD responsiveness and OS with IKZF1 and KPNA2 gene expression level in pomalidomide and dexamethasone therapy. A cohort of 44 MM patients treated with pomalidomide with GEP measured before initiation of chemotherapy was used in this study. (A) Responsiveness to pomalidomide in quartiles of IKZF1 expression. No patient in the lowest IKZF1 quartile expression responded to pomalidomide treatment. (B)The gene expression of the 11 top lenalidomide-regulated putative CRBN-interacting proteins was analyzed to examine the association between drug response and survival by using COX modeling. IKZF1 was identified as the top gene, which expression is associated with OS (P = .002). (C-D) Low IKZF1 and high KPNA2 expression levels were correlated with shorter OS.