Aptamer:toxin conjugates that specifically target prostate tumor cells.

We have used RNA aptamer:gelonin conjugates to target and specifically destroy cells overexpressing the known cancer biomarker prostate-specific membrane antigen (PSMA). Aptamer:toxin conjugates have an IC50 of 27 nmol/L and display an increased potency of at least 600-fold relative to cells that do not express PSMA. The aptamer not only promotes uptake into target cells but also decreases the toxicity of gelonin in non-target cells. These results validate the notion that "escort aptamers" may be useful for the treatment of specific tumors expressing unique antigen targets.