Two patients taking part in trials of an experimental antibody drug developed to treat prostate cancer have seen their advanced and inoperable conditions almost disappear.
The men, whose aggressive tumours had grown well beyond the prostate gland into abdominal areas, were treated at the Mayo Clinic in Rochester, Minnesota, US, with the drug ipilimumab.
The men received traditional hormone therapy - to remove testosterone which fuels prostate cancer - along with single doses of ipilimumab, which boosts the immune system’s response to the cancer.
Tests looking at their prostate specific antigen (PSA) levels showed it had dropped in both men enough for them to undertake surgery, but when doctors operated they found the tumours had shrunk ‘dramatically’.
Trial leader Dr Eugene Kwon said: ‘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.’
Further research is planned to understand more about the mechanisms of the antibody and how best to use it on patients.
Mayo clinic urologist Dr Michael Blute said: ‘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.’