According to a new study, researchers have identified the cause of chloroquine's anti-cancer effect.
Experimental animal models have previously shown that chloroquine, a commonly used antimalarial agent, has an anti-cancer effect when combined with conventional chemotherapy, but researchers have only assumed that the effect was due to an increased sensitivity of cancer cells to chemotherapy due to a direct effect on the tumor cells by chloroquine.
The study showed that chloroquine normalizes the abnormal blood vessels within the cancer, resulting in an increased barrier function and tumor perfusion. The enhanced barrier blocks cancer cell proliferation and metastasis while the improved tumor perfusion boosts the effect of chemotherapy.
Chloroquine has been used for over 5 decades for the prevention and treatment of malaria as well as for the treatment of rheumatoid arthritis and lupus erythematosus.
Recently, chloroquine has also been used as a sensitizing agent in conjunction with radiation and chemotherapy to improve their anti-cancer effects. Chloroquine blocks autophagy, a process used by cancer cells to survive chemotherapy and radiation, thereby decreasing the resistance of the cancer cells to treatment. Chloroquine has various common adverse effects, but most serious side effects only occur with long-term use.
The anti-cancer effect of the antimalarial agent chloroquine when combined with conventional chemotherapy has been well-documented in experimental animal models. To date, it was assumed that chloroquine increases the sensitivity of cancer cells to chemotherapy by means of a direct effect on the cancer cells.
However, a recent study by investigators at VIB and KU Leuven has demonstrated that chloroquine also normalizes the abnormal blood vessels in tumors.