Vitamin D Mimic May Improve Prostate Cancer Therapy
Thursday August 28, 2003 (1543 PST)
ISLAMABAD, August 29 (Online): Treating prostate cancer cells with a vitamin D-like compound appears to make them more susceptible to the destructive effects of radiation, lab experiments show.
If this research holds up, pretreating prostate cancer patients with the vitamin D "analog" could offer two benefits. It might allow the radiation dose to be reduced, resulting in fewer side effects, or it could enhance the effectiveness of standard dose radiation.
However, "our findings first need to be verified in animal studies followed by testing in humans," Dr. Constantinos Koumenis, from Wake Forest University in Winston-Salem, North Carolina, told.
The analog, which is produced by Abbott Labs under the name Zemplar, is already approved by the FDA as treatment for an overactive parathyroid gland "which should expedite testing in prostate cancer patients," Dr. Koumenis noted.
Optimistically, "testing in humans could begin in a year," he added.
In the new study, the researchers irradiated human prostate cancer cells that were exposed to Zemplar, calcitriol (the active form of vitamin D), or were untreated. The results are published in the online issue of the British Journal of Cancer.
The killing effect of radiation was stronger when the cells were first exposed to Zemplar or calcitriol. In addition, the enhanced destruction was fairly selective, leaving normal prostate cells relatively unscathed.
"The reason for the synergy between Zemplar and radiation is unclear," Dr. Koumenis noted. However, vitamin D by itself has been shown to slow the growth of prostate cancer cells, he added.
Although calcitriol was effective in these experiments, it has one major drawback: it tends to cause high calcium levels in the blood, which can lead to a number of problems. Zemplar, by contrast, appears much less likely to produce this metabolic disturbance.
End.
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