Discovery of pyrrolo[2,3-d]pyrimidine derivatives with inhibitory effect on liver cancer stem cell.

Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related mortality worldwide. The malignancy of HCC is closely linked to liver cancer stem cells (CSCs), making the application of anti-CSC drugs a promising therapeutic approach. In this study, we report the discovery of novel pyrrolo[2,3-d]pyrimidine derivatives as potent inhibitors of liver CSC. Structural optimization and anti-CSC screening led to the identification of improved compounds 6i, 6j, and 7e, which significantly inhibited Huh7 sphere formation while exhibiting low toxicity to standard 2D-cultured tumor cells. Notably, compound 6i sensitizes both parental and Lenvatinib-resistant HCC cells to Lenvatinib treatment, showing a synergistic interaction. Collectively, these findings establish the pyrrolo[2,3-d]pyrimidine as a promising scaffold for targeting liver CSC and provide a potential combination strategy to overcome Lenvatinib resistance in advanced HCC.