Therapy of primary and metastatic liver cancer by human iPS cell-derived myeloid cells producing interferon-β.

BACKGROUND: iPS-ML are myeloid lineage cells with a proliferative capacity derived from induced pluripotent stem (iPS) cells. This study aimed to examine therapeutic effect of iPS-ML producing interferon-β (iPS-ML/IFN-β) towards primary and metastatic liver cancer and investigate the mechanism of that effect.

METHODS: We established a xenograft model of liver metastasis by injecting the spleen of SCID mice with MKN-45 human gastric cancer cells and also a primary liver cancer model by injecting SK-HEP-1 human hepatocellular carcinoma cells into the liver. After cancer lesions were established, iPS-ML/IFN-β was administered by intraperitoneal injection, and therapeutic effect was evaluated.

RESULTS: The i.p. injection of iPS-ML/IFN-β resulted in a significant retardation of cancer progression and prolonged mouse survival. The infiltration of i.p. administered iPS-ML into tumor lesions located below the liver capsule was observed, suggesting tumor-directed migration and penetration of the liver capsule by iPS-ML. The IFN-β concentration in the liver was maintained at levels sufficient to exert an anti-cancer effect for at least 3 days post-injection, accounting for the potent therapeutic effect obtained by injection two to three times per week.

CONCLUSIONS: This study demonstrates the therapeutic potential of the iPS-ML/IFN-β in patients with liver cancer.