Prostate cancer resistant to conventional treatment could be all but wiped out by a therapy that boosts the immune system, claim researchers. Tests carried out in combination with chemotherapy drugs achieved almost complete remission in mice. The US scientists used low doses of the drug oxaliplatin, which has a unique ability to activate cancer-killing immune cells in small tumours but works less well in large, aggressive tumours. Tests of new drug oxaliplatin, carried out in combination with chemotherapy drugs, achieved almost complete remission in mice. Each year in the UK around 41,000 men are diagnosed with prostate cancer and 11,000 die from the disease . The problem is partly caused by immune system ‘B-cells’ that put a brake on the body’s defences in prostate and other cancers. In their study, the researchers found a way of blocking the development or function of these B-cells, or removed them entirely before using oxaliplatin. The prostate tumours were ‘almost completely destroyed’ by the mice’s own immune cells, the team said. Lead scientist Shabnam Shalapour, of the University of California at San Diego, said: ‘The presence of such B-cells in human prostate cancer calls for clinical testing of this novel therapeutic approach.’ Because of the effect of the immune system, advanced and aggressive prostate cancer does not typically respond to chemotherapy, researchers said. B-cells also undermine the effectiveness of promising new drugs called checkpoint inhibitors which ‘unmask’ cancer cells allowing them to be recognised by the immune system. Prostate cancer cells. There are currently few options for men with aggressive drug-resistant prostate cancer that has started to spread . But researchers also managed to get a checkpoint inhibitor – combined with chemotherapy – to work after wiping out the B-cells in one test. Each year in the UK around 41,000 men are diagnosed with prostate cancer and 11,000 die from the disease. While early treatment is often highly successful, there are few options for men with aggressive drug-resistant prostate cancer that has started to spread. B-cells play a number of vital immune system roles, including the production of antibodies. They can also tell the immune system to slow down when it is getting overheated, but this can be counter-productive in cancer treatment. Professor Michael Karin, study co-author and also from the University of California at San Diego, said there might be implications for the treatment of other types of cancer. The William Pereira designed Geisel Library at the University of California San Diego. Researchers there have made this new prostate cancer breakthrough . ‘Similar immunosuppressive B-cells can be detected in other human cancers,’ he added. ‘This indicates that B-cell-mediated immunosuppression might be the reason several other cancers are also unresponsive to checkpoint inhibitors, raising the hope that chemoimmunotherapy will have broader applications for many cancer types.’ Symptoms of prostate cancer include the need to urinate more frequently, especially at night, painful ejaculation and blood in the urine or semen. Men may also have pain or stiffness in the lower back, hips or thighs. However, not all men with the disease will have symptoms and often the cancer is spotted only in a routine check-up. Early diagnosis is crucial – up to 98 per cent of men who are diagnosed when the cancer is still contained within the gland will live for more than five years. That drops to just 30 per cent if the cancer has spread.
US scientists used drug oxaliplatin to fire up cancer-killing immune cells .
Drug blocks ‘B-cells’ that put a brake on body’s defences against cancer .
There are currently few options in cases of aggressive  prostate cancer .