LONDON, ENGLAND (Reuters) - British scientists said on Monday they had developed potential new antibody treatments that could "super charge" the body's immune system to help it fight some types of cancer.

The scientists said the treatment had shown significantly increased survival from neuroblastoma - a type of childhood cancer - in laboratory tests, and they hoped it could one day be used to treat children with the disease.

The researchers developed two monoclonal antibodies (mAbs) called anti-41BB and anti-CD40, and investigated a third called anti-CTLA4, all of which bind to molecules in the immune system.

They found that 40 to 60 percent of tumours treated with the antibodies were destroyed in laboratory tests.

With more aggressive tumours, the antibodies appeared not to work so well, but when the researchers paired one of the mAbs with a particular peptide, or protein fragment, they destroyed about 40 to 60 percent of these too.

The scientists said these antibodies were designed to recognise the response the immune system produces and stimulate it, making it more effective in attacking cancer cells.

"It is hoped that these antibodies can be used to boost or 'super charge' the body's immune system to help it fight cancer," the researchers wrote in a report on their study.

Juliet Gray, a clinical lecturer in oncology at the University of Southampton who led the study, stressed the work was at a very early stage and more research was needed.

"Although this work is still at a pre-clinical stage, we hope it has enabled us to identify a way that we can provide effective immunotherapy treatment against neuroblastoma," she said in a statement about her findings, which were scheduled to be presented at the National Cancer Research Institute (NCRI) conference in Birmingham on Monday.

Neuroblastoma is a cancer that affects developing nerve tissue and accounts for 15 percent of cancer deaths in children.

Some 60 percent of children with neuroblastoma can be successfully treated with chemotherapy, Gray said. "But for those children who don't respond well to this treatment, immunotherapy could become a vital new treatment option."

Immunotherapy is a relatively new form of treatment, but several monoclonal antibodies - tailor-made proteins that can detect proteins attached to cancer cells and be used to block their growth - are already licensed to treat adult cancers.

The scientists pointed to rituximab - sold as Rituxan or MabThera from Genentech and Biogen Idec through Roche - and alemtuzumab - sold as Campath from Bayer AG and Genzyme Corp - as examples of drugs using mAbs in a similar way.

Martin Glennie of Southampton University, who also worked on the study, said the next stage of research would be "to see if the treatment is a safe and effective treatment for children" and to investigate how these antibodies can be used in combination with other treatments to maximise their effect.