CD133 inhibition in cancer stem cells and the cytotoxicity of specific 3-phenylthiazolo[3,2-a]benzimidazoles including their design, direct synthesis, and in vitro biology were investigated.103 Compound 219 decreased the surface expression of CD133 on cells by 50% and showed strong anticancer activity against both cancer cell lines with IC50 values of 9 and 12 μM, respectively. Here, PROM1 is linked to cancer.