Prostate news article, September 2004
| THE IMMUNE SYSTEM
CAN BE USED TO KILL PROSTATE CANCER USING PROSTATE SPECIFIC MEMBRANE AGENT AS A TARGET Dr Charlotte Foley MA BMBCh MRCS Prostate Cancer Research Centre, University College London, Institute of Urology |
Scientists talk of identifying prostate cancer 'markers' to target with 'magic bullet' therapies to destroy only 'marked' cells. PSMA (Prostate Specific Membrane Antigen), a protein found on the surface of prostate cells, some duodenum, brain, colon and kidney cells and blood vessels within tumours, appears to be such a marker. The more aggressive the prostate cancer, the more protein marker found on its surface.
First, a means of targeting the marker has to be found. The body's immune system can already recognise 'self' from 'non-self', and selectively kill foreign cells such as bacteria. The potential for turning the immune system's killing machinery against cancer cells is a major focus of research.
Writing in The Prostate (2004; 61:12-25), Dr Richard Junghans from Harvard has reported successes with 'designer T-cells' that target prostate cancer cells. His team has created T-cells that specifically bind PSMA on prostate cancer cells in the laboratory and kill them while PSMA-free cells are spared. Cancer cells injected under the skin of mice grow into visible tumours. However, when designer T-cells were simultaneously injected into the blood stream, tumours either grew much more slowly or, in 56% of mice, didn't grow at all.
The beauty of designer T-cells is that after injection into the blood stream, they circulate throughout the body to wherever cancer deposits are. Next a clinical study is planned, using low doses of patients' own modified T-cells to assess the risk of collateral damage to normal PSMA-bearing organs. We can expect further interesting instalments.