Response to standard and novel drugs in the zebrafish model. (A) Fluorescent microscopy images of CM-Dil–stained MM1S and MM1R xenografts at 0, 24, 48, and 72 hpi. (B) Tumor growth curves of MM1S and MM1R cells xenografts indicating that MM1S xenografts are responsive to dexamethasone treatment whereas MM1R xenografts are resistant. (C) Percentage of MM1S xenografts in zebrafish showing no response after treatment with bortezomib (Bor; n = 22), lenalidomide (Len; n = 22), dexamethasone (Dex; n = 22), AZD6244 (n = 18), 17-AAG (n = 22), rapamycin (Rapa; n = 18), AS703026 (n = 18), and dimethyl sulfoxide (control; n = 20), respectively. Error bars indicate standard errors. (D) Summary of percentage of MM1S, MM1R, OPM1, and RPMI8226 larvae without response with various indicated novel agents. (E) Individual fluorescence microscopy images of CD138⁺ MM cells from newly diagnosed MM patient xenografts in zebrafish before and after treatment with bortezomib (n = 8), lenalidomide (n = 8), dexamethasone (n = 8), and dimethyl sulfoxide (n = 8), at 0, 24, 48, and 72 hpt, respectively. (F) Percentage of primary patient MM cell xenografts without response to lenalidomide, bortezomib, and dexamethasone. Ctrl, control.