24 Jun 2013

Are we moving closer to treating variant CJD?

A blood test for variant CJD – once known as mad cow disease – has moved a step closer after trials on 5,000 blood samples provided by the American Red Cross proved it does not falsely say the disease is present.

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The test, devised by scientists at the Medical Research Council’s prion unit and the NHS National Prion Clinic, based in Queen’s Square, central London, only detects seven in 10 cases of vCJD.

But the team say that the fact there are no false positives means it should now be suitable for the anonymous screening of a large sample of UK donors to see whether the test is able to detect silent infection – and it could be developed to screen national blood supplies.

Last year, Channel 4 News exclusively revealed that the test was already being offered to patients from around the UK and some from abroad who are suspected of having vCJD. Until now the only way of confirming diagnosis has been through tonsil biopsies, while the patient is alive, or from the brain after they have died.

It now needs a further UK trial of between 20,000 and 30,000 blood samples and the team is looking at speeding up their current test in order to be able to deal with such a large volume.

Studies of tonsil samples indicated that one in 4,000 people in the UK (15,000 in all) could be infected with vCJD. But last summer it was (quietly) announced by the Health Protection Agency that a further study on appendixes showed it may be double that number – one in 2,000. Indeed in the older age group tested, nearly one in 1,000 appendix samples tested positive.

The news was announced to 100 families of patients with all forms of CJD, including genetic and sporadic as well as vCJD, who were attending an open day of the MRC prion unit held to mark 100 years of the Medical Research Council.

At the same time, Professor John Collinge, who is part of the team developing the blood test, also announced that they have developed a human version of an antibody that can block Prion infection in mice. The antibody is being tested further prior to seeking regulatory approval for clinical trials in patients with CJD.

Professor Collinge told Channel 4 News that while the antibodies have been in development for 10 years, they have now been manufactured and they were now “very close” to becoming a treatment.

He said they were now conducting safety testing and other work needed before seeking regulatory approval for human clinical trials which he hoped would begin within the next 12 months.

If successful, this could lead to the first effective treatment for dementia.

Furthermore, the unit has shown that this antibody is able to block some of the damaging effects on brain tissue by a toxic substance called amyloid beta which is involved in Alzheimer’s disease suggesting the treatment may have a wider role in treating dementia.

Colin Beatty, whose wife Annie died aged 70 from sporadic CJD, welcomed the news. Mr Beatty said that when they were first given the news it was a bombshell, not least because they knew it was a death sentence.

Mrs Beatty survived far longer than most patients with sporadic CJD. Many die three to six months after diagnosis but she lived for more than four years and the number of blood tests and MRI scans she had were used in the research on how the disease progresses.

“We knew that even if they come up with a cure it would be too late for Annie,” Mr Beatty said. “But we said let’s do it for the sake of research.”

Now, he said, he is beginning to feel optimistic that a treatment is in sight.

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