Wednesday July 18 2012
IVIG may attack 'toxic' Alzheimer's proteins and halt symptoms
Widespread media coverage tells us today of a new drug that ‘halts’ Alzheimer’s symptoms ‘for three years’. The news is based on a press release issued yesterday that highlighted positive early results of research into the use of intravenous immunoglobulin to treat Alzheimer’s disease.
Intravenous immunoglobulin (IVIG) is a medication made by harvesting antibodies from donated blood. It is currently used to treat severe forms of infection and a number of autoimmune conditions (where the immune system attacks healthy tissue).
The idea behind using IVIG to treat Alzheimer’s disease is that it could encourage the immune system to ‘attack’ abnormal clumps of protein (amyloid plaques) that can develop in the brains of people with Alzheimer’s disease.
Some of the media coverage of the press release was inaccurate. The Daily Express tells us there is a 'pill to beat Alzheimer’s', when IVIG is actually given by injection into a blood vessel. The Daily Mail describes it as a 'new vaccine', which is technically incorrect as it implies only one injection needs to be given when in fact IVIG was injected every two weeks.
Once past the somewhat misleading headlines, most coverage does then mention that it may be 10 years before this drug might actually be available, if it passes further scrutiny. IVIG can also be very expensive to manufacture so this may limit its availability on the NHS.
Limited conclusions can be drawn from this research as it is early stage, was conducted on a small number of people, and was not peer-reviewed. Larger studies that compare IVIG to other existing treatments for Alzheimer’s disease are required to determine how safe and effective the drug is.
What did the research involve and what were its findings?
According to the press release, 24 people were treated with IVIG for six months and these were compared to a group of five people who were treated with a placebo. This part of the study was followed by an additional 12-month extension (where all participants including the placebo group received IVIG). Participants were then offered a further 18 months of IVIG treatment to assess the long-term effects of the drug. The press release reports the following preliminary findings:
- Participants treated with IVIG at a dose of 0.4g per kg of their bodyweight every two weeks for 36 months (four participants) had the best outcome with no decline on several standard measures of cognition, memory, daily functioning and mood at three years follow-up.
- Eleven participants who received IVIG for 36 months had favourable outcomes in terms of their thinking abilities, behaviour and daily function.
- Five participants initially treated with placebo who then switched to IVIG declined while on placebo, but experienced less rapid decline while receiving a uniform dose of IVIG.
How does this new drug seem to work?
According to the press release, IVIG is a blood product that is administered intravenously. Each dose contains pooled antibodies extracted from the plasma of more than 1,000 blood donors. IVIG can help immune-deficient patients reduce their risk of infections.
In discussing how the drug IVIG is thought to work, Dr Anne Corbett of the Alzheimer’s Society has said: “The treatment is thought to work by clearing toxic proteins called beta amyloid from the brain, allowing brain cells to function properly.”
How does the new drug compare to existing treatments?
As this research is in the early stages of development (phase II trial), the drug has not been compared to existing treatments.
During phase II trials of testing, a drug’s effectiveness in treating the targeted condition in humans is examined for the first time and more is learnt about appropriate dosage levels and safety. This stage usually involves 200-400 volunteers who have the condition that the drug is designed to treat. The drug’s effectiveness is then examined and more safety testing and monitoring of its side effects are carried out.
Phase III trials are the next stage a drug must go through before it can be licensed for general prescribing by doctors. These trials are designed to give the drug as unbiased a test as possible to ensure that the results accurately represent its benefits and risks. The large numbers of participants and the extended period of follow-up give a more reliable indication of whether the drug will work and allows rarer or longer-term side effects to be identified.
Read more about the treatment of Alzheimer’s disease.
The press claims this could be a 'wonder drug' for Alzheimer's - is this true?
There is no cure yet for Alzheimer’s disease, though medication is available that can improve symptoms in some people. Research efforts are concentrating on both preventing the deterioration of early symptoms and treating the established disease. This study appears to be investigating the first option, but larger studies of the immunoglobulin will be required before newspapers can truly call IVIG a ‘wonder drug’.
The research suggests that IVIG can slow down the progression of some of the symptoms of Alzheimer's but this certainly does not amount to a cure. It is unclear how long the beneficial effects of IVIG may last or whether everyone treated with IVIG would experience any benefits.
In discussing the research, study leader Dr Norman Relkin said: “It is crucial that we find effective, long-term treatments. This is the first study to report long-term stabilisation of Alzheimer’s symptoms with IVIG. While the small number of participants may limit the reliability of our findings, we are very enthusiastic about the results.”
When could we expect to see the new drug on the market?
Professor Clive Ballard, director of research at the Alzheimer’s Society, has said: “If the phase III trials are successful, and it can be made cost-effective, this drug could be on shelves within 10 years.” He added: “We know it is safe, but the real test will be whether these initial promising results can be replicated in larger groups.” This seems a reasonable ballpark timescale based on how long it usually takes to get a treatment through phase III trials. The big question is whether it will get through these further tests.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on twitter.