Loss of RFX7 or AMBRA1 attenuates the response to CC-122. (A) Cell fitness assessment of SU-DHL-4 cells with knockout of RFX7 or AMBRA1 in the presence or absence of CC-122, compared with control cells by flow cytometry–based CRISPR competition assay as described in Figure 3A. Data are shown as the mean ± SD; 2 biological replicates. Data were analyzed by 2-tailed unpaired Student t test. *P < .05; **P < .01; ***P < .001; NS, P > .05. (B) Heat map showing the CC-122–induced enrichment of DLBCL cells with loss of CRBN, RFX7, or AMBRA1 in the CRISPR competition assay. Enrichment score is calculated as FC of the RFP⁺/GFP⁺ ratios between cells treated with 50 µM CC-122 vs their DMSO controls on day 9, 10, or 11, as indicated. (C) Immunoblot analysis of SU-DHL4-Cas9 cells transduced with lentiviral vectors expressing the indicated sgRNAs. Cells were treated with either DMSO or CC-122 at the indicated concentrations for 24 hours. (D) Flow cytometry of SU-DHL-4 cells with expression of the indicated sgRNAs. Cells were continuously treated with DMSO or 50 µM CC-122 for 11 days, followed by staining with annexin V and 7-AAD.