Arsenic Trioxide Enhances Radiation Therapy Effectiveness

Researchers at the University of Minnesota investigated the impact of arsenic trioxide on primary cultures of endothelial cells and tumor tissue under varying pH and pO[subscript]2 environments. The study aimed to determine whether combined arsenic trioxide and radiation therapy could synergistically increase the effectiveness of cancer treatment. The results showed that arsenic trioxide (Trisenox, TNX) preferentially damaged endothelial cells in low-oxygen environments, leading to tumor cell death and enhanced sensitivity to radiotherapy.

Key Takeaways:

• Arsenic trioxide (Trisenox, TNX) reduces blood perfusion in FSaII tumors by 53% within 2 hours after injection, as demonstrated in a study using female C3H mice.
• Carbogen breathing alone reduces tumor perfusion by 33% within 2 hours, but when combined with TNX, it eliminates further reduction in blood perfusion.
• In vitro, TNX exposure increases JNK MAP kinase activity preferentially in endothelial cells cultured in acidic or hypoxic environments.
• In vivo, TNX injection significantly elevates tumor oxygenation, with median oxygenation increased by 3 or 5 days after injection.
• Subsequent irradiation demonstrates synergistic enhancement of tumor-growth delay when radiation and TNX injection are fractionated at 3-day or 5-day intervals.

Statistics:

• 53% reduction in blood perfusion in FSaII tumors within 2 hours after a single intraperitoneal injection of 8 mg/kg TNX.
• 33% reduction in tumor perfusion within 2 hours after carbogen breathing alone.
• 3 or 5 days after TNX injection, median oxygenation in FSaII tumors is significantly elevated.

Sources:

• Griffin, R. J., et al. "Preferential action of arsenic trioxide in solid-tumor microenvironment enhances radiation therapy." International Journal of Radiation Oncology Biology Physics, vol. 61, no. 5, 2005, pp. 1516-1522.
• University of Minnesota School of Medicine, Department of Therapeutic Radiology.