Selective targeting of chr1q-amp tumor cells with a selective PBX1 inhibitor. (A) Survival analysis of patients with MM or with breast, ovarian, lung, or brain cancer based on the PBX1 signature expression (red: high; black: low; n = 320 genes; supplemental Table 5). Kaplan-Meier plots and statistical analysis depict the significantly poorer survival of patients with an active PBX1 signature. (B) Cytotoxicity profiles (n = 3) of MM cells (MM.1S, OPM2, U266, NCU.MM1) and breast (MCF-7, LTED), ovarian (OVCAR-3, A2780), lung (A549, H69AR), and brain (SNB-75) cancer cell lines 48 hours after treatment with the small molecule PBX1 inhibitor T417. Three independent experiments were performed per cell line, and 50% inhibitory concentration (IC₅₀) values were calculated using a nonlinear fitting model (fitting line represented here). (C) Cell cycle profiling of 11 cancer cell lines 48 hours after treatment with 1% DMSO (control) or T417 (20 μM). Three independent experiments were performed per cell line. Statistical comparisons were performed using a 2-way nonparametric analysis of variance (ANOVA) with a post hoc multiple-comparisons test. (D) Assessment of PBX1, FOXM1, NEK2, and E2F2 mRNA levels in 11 cancer cell lines 16 to 20 hours after treatment with 1% DMSO (control) or T417 (20 μM). Bar graphs illustrate transcriptional levels normalized to corresponding control samples (n = 3 replicates). Analysis was performed using a paired Student t test. (E) Tumor volumes of MM.1S xenografts measured in vehicle-treated (control) and T417-treated (10 mg/kg per injection) mice across experimental time points. Statistical analysis was performed using a 2-way ANOVA with a post hoc multiple-comparisons test. (F) Tumors explanted from control- and T417-treated mice at the termination of the study (day 23). (G) Heat map representation of PBX1, FOXM1, NEK2, and E2F2 mRNA levels assessed by RT-qPCR. For the in vivo experiment in tumor explanted cells, values represent pairwise comparisons of the T417 group (D1-D5) against the vehicle-treated group (C1-C5). For in vitro primary myeloma PC samples, values represent T417-treated (20 μM) vs control-treated (1% DMSO) cells. Gray boxes correspond to nonapplicable comparisons resulting from undetectable levels of mRNA in control-treated cells. (H) Cell viability of primary chr1q-amp MM (X1, X2, X3; green), nonamplified MM (X4, X5; orange), and normal donor PBBCs (orange) at 48 hours after treatment with 1% DMSO (control) or T417 (20 μM). Nonlinear data fitting and IC₅₀ calculations were performed as described in (B). *P < .05; **P < .01; ***P < .001; ****P < .0001. HR, hazard ratio; n/a, not applicable (noncalculable); Rel., relative; Undet., undetermined.