Source: Press Association

Two men with advanced and inoperable prostate cancer have staged dramatic recoveries after being treated with an experimental antibody drug.

Both are now cancer-free and have returned to normal life after they took part in a trial of a drug called ipilimumab that boosts the immune system.

Before treatment at the Mayo Clinic in Rochester, Minnesota, US, each of them had aggressive tumours that had grown well beyond the prostate gland into abdominal areas.

Trial leader Dr Eugene Kwon said: "The goal of the study was to see if we could modestly improve upon current treatments for advanced prostate cancer.

"The candidates for this study were people who didn't have a lot of other options. However, we were startled to see responses that far exceeded any of our expectations."

First, the patients received traditional hormone therapy to remove testosterone, which fuels prostate cancer. Researchers then introduced a single dose of ipilimumab. The drug is an antibody which builds on the hormone therapy and boosts the immune system's response to the cancer.

Both patients saw their prostate specific antigen (PSA) levels drop to the point where they became eligible for surgery. PSA is a protein in the blood that allows doctors to monitor prostate cancer.

When the surgeons made their incisions, they had a surprise.

Mayo clinic urologist Dr Michael Blute said: "The tumours had shrunk dramatically. I had never seen anything like this before. I had a hard time finding the cancer. At one point the pathologist asked if we were sending him samples from the same patient."

Further research is now planned to understand more about the mechanisms of the antibody and how best to use it on patients, but Dr Kwon added: "This is one of the holy grails of prostate cancer research. We've been looking for this for years."

Copyright © 2009 The Press Association.

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