MUC1-C inhibitor GO-203 is cytotoxic in CTCL primary cells at 48 and 72 hours. (A-D) MUC1 and TCR Vβ rearranged double-positive malignant population of our interest was FACS sorted from 2 of the patients with L-CTCL (Figure 2D) and treated with varying concentrations (3.5, 5, and 7.5 μM) of GO-203 and CP-2 daily. Cell viability assessed at 48 (A and B) and 72 hours (C and D) demonstrated increased sensitivity to GO-203 in comparison with CP-2 and untreated cells that were statistically significant. Experiment was performed in triplicate. Asterisk indicates a statistically significant P value of <.05.