A toxin derived from a reclusive sea creature resembling a translucent doughnut has inspired UT Southwestern Medical Center researchers to develop a related compound that shows promise as a cancer treatment. In a study appearing online this week in the Proceedings of the National Academy of Sciences, the UT Southwestern scientists detail how the toxin blocks uninhibited reproduction of cultured human cancer cells while leaving healthy cells unaffected. An accompanying study in PNAS shows that, in pre-clinical trials, a synthetic form of the toxin reduced human tumors implanted in mice without the harmful side effectsterm seen using other cancer drugs.