A protoxin that kills prostate cancer

Scientists have found a way of using a protein made by prostate cancer to target and kill the cancer cells themselves. In preliminary studies the new therapy affected only the prostate, without causing damage to other healthy tissues, and now it is being tested in a phase I clinical trial.

Sam Denmeade, associate professor of oncology at John Hopkins University, USA, reported to the EORTC-NCI-AACR2 Symposium on Molecular Targets and Cancer Therapeutics in Prague that he and his team3 had developed a protoxin, named PRX302, by modifying an inactive molecule, proaerolysin (PA). They engineered PRX302 to be activated by prostate-specific antigen (PSA) – a protein made in higher than normal levels by prostate cancer. Once activated, they hoped that it would target and kill prostate cancer cells specifically.

He explained: “This represents a different kind of ‘targeted’ therapy, in that it seeks to use a protein made by the cancer to destroy itself.”