Cancer drug success as 'killer cells' attack disease
A RADICAL new form of cancer treatment that relies on the body's natural "killer cells" to attack tumours has proved a success in the first clinical trials on patients suffering from advanced skin cancer, scientists have said.
The immune-therapy is based on a biologically designed drug that binds tumour cells to the killer T-cells of the immune system, causing the cancer cells to self-destruct. Scientists hope that the approach can be adapted for a wide range of other tumours, such as prostate, lung and ovarian cancers.
Results of the phase-1 clinical trial designed to test the drug's safety on 31 patients with advanced melanoma - the most dangerous form of skin cancer - showed there were few serious, long-lasting side effects and that in some cases the tumours started to shrink.
The findings, released at the American Association for Cancer Research in San Diego, California, were better than expected and have already led to a phase-2 clinical trial to test the drug's efficacy on skin cancer patients in both the UK and the United States, scientists said.
"I think this is at the high end [of expectations]. A number of phase-1 trials go nowhere but what we see here is a drug that works as predicted and has significant clinical activity. It is very, very exciting," said Mark Middleton, professor of experimental cancer medicine at Oxford University, who presented the results.
Of the 16 patients in the group who received clinically useful doses of the drug, four responded to treatment and two of these met the strict clinical criteria that are used to define whether or not a patient with solid tumours responds to an experimental treatment.
Two of the patients in the advanced stages of the disease have continued with the immune-therapy treatment on compassionate grounds and still show signs of benefiting from the drug, known as IMCgp100, nearly a year after the trial began.
Many of the patients experienced tumour inflammation and rashes, which indicates that their immune systems had been stimulated to start attacking the cancer cells within the skin, said Professor Middleton.
"The one aspect that did surprise us is the extent of tumour inflammation that is possible to achieve from just a single dose of the drug, because we thought it might take several weeks to get going," Professor Middleton said.
IMCgp100 is a small, man-made antibody designed specifically to bind tightly to the unique protein antigens sticking out from the surface of the cancer cell.
At the other end of the synthetic antibody is another binding site that attaches to passing killer T-cells in the blood, bringing them close enough to destroy the cancer cells while hopefully leaving ordinary healthy cells unharmed.
The intellectual property behind the technology is owned by a small spin-off company based near Oxford University called Immunocore which over the past year or so has signed major deals potentially worth hundreds of millions of pounds in future investment with three multi-national pharmaceuticals companies.
Bent Jakobsen, the chief scientific officer of Immunocore, who began working on the technology more than 20 years ago, said he was surprised just how well some of the patients responded, with one individual showing an 80 per cent reduction in tumour size.
"Some tumour shrinkage was over 30 per cent, others were less than 30 per cent, but the drug was not designed to work after a single dose so in some respects this was a surprise to us," Dr Jakoben said.
"Right now I find it very, very encouraging to get these results."