MUC1-C inhibitor GO-203 is cytotoxic in CTCL cells. (A-E) Hut78, Myla, and H9 cells were treated with varying concentrations of GO-203 and the inactive analog CP-2 (1-10 μM) each day for 3 days. Cell Titer Glo was added and viability was measured at 72 hours. The results are expressed as relative percentage viability (mean ± SD of 3 determinations) compared with the control treated with phosphate-buffered saline (PBS; A-C). Cells were incubated with PI and annexin V and analyzed by flow cytometry at 72 hours. The results are expressed as relative percentage of cells with late apoptosis and necrosis (mean ± SD of 3 determinations) compared with the control treated with PBS (D-F). Asterisk indicates a statistically significant P value of <.05.