Prostate cancer vaccine treatment trial started

A trial is just starting into the benefits of a vaccine which has the potential to harness the body's own immune system to better fight prostate cancer.

Throughout 1999, about 60 volunteer patients at St George's Hospital, London will receive a monthly injection of the vaccine.  The patients concerned all have somewhat advanced disease, with PSA levels over 30 which are no longer being held in check by androgen hormone therapy.

How the vaccine works

The vaccine is derived from human prostate cancer cells.  These have, first, been 'immortalised' so that they can multiply indefinitely outside the body.  Those to be used for the vaccine are then 'inactivated' by radiation, so that they are no longer able to divide and, hence, grow in number.  They are then injected into the patient whose body will very likely recognise the cells as foreign.  The patient's own immune system will then try to reject the foreign cells and kill them.  The behaviour is much the same as when a transplanted organ is rejected.  Once the body's immune system is stimulated by the vaccine in this way, it should also set about destroying the live cancer cells which are already within the patient's body.

First time in humans

Such a procedure has been tested in rats but with a vaccine derived from prostate cancer in rats.  This trial will be the first time the actual vaccine has been used with human patients.  Its effectiveness will be measured through the indirect marker of changes in the PSA level and through scans of the patients.  The trial will also assess the impact of side effects such as inflammation of the injection site and feverish flu type symptoms.