A group of Alzheimer’s patients treated for 3 years with an immunotherapy drug showed no symptom decline over the treatment period. The patients were taking part in a small placebo-controlled phase 2 trial testing Baxter’s intravenous immunoglobulin (IVIG) as an immunotherapy for Alzheimer’s.

IVIG is a blood product that is mainly used to treat patients with immune deficiencies, autoimmune diseases and acute infections. Each dose, which is given intravenously, contains antibodies extracted from the plasma of over 1,000 blood donors.

The first report of the 3-year trial was presented on Tuesday at the Alzheimer’s Association International Conference in Vancouver, Canada.

Study leader Norman Relkin, of Weill Cornell Medical College, New York City, told the press:

“This is the first study to report long term stabilization 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.”

The 3-year trial was an extension of one that earlier reported positive results with a shorter period of treatment (18 months). In that shorter trial, some of the 24 patients were given placebo and the rest were given various doses of IVIG for the first 6 months, then for the remaining 12 months, they all received various doses of IVIG.

In the extended trial, 16 of the 24 participants went on to receive treatment for another 18 months, for a total of 36 months. All received a single standardized dose of 0.4 mg/kg every 2 weeks, including 5 who had originally been on placebo, while the others had been on various doses of IVIG.

The participants were assessed at the start and various endpoints using several standard measures of cognition, memory, ability to function and carry out daily tasks, and mood.

The researchers found the group that was on 0.4 mg/kg of IVIG every 2 weeks for the whole 36 months showed the best results: no decline in symptoms of Alzheimer’s at the end of three years.

The group of 5 that was on placebo for the first 6 months and then switched to IVIG, showed symptom decline while on placebo, but then the decline was less rapid while they were on a constant dose of IVIG.

Compared to that group of 5, the remaining 11 patients who had IVIG for the full 36 months (with varied doses up to month 18), showed better outcomes in terms of thinking abilities, behavior and daily function.

Relkin said a phase 3 trial was already under way and, “in less than one year, we’ll have more definitive data on the efficacy of 18 months of IVIG treatment.”

Alzheimer’s disease progresses over many years. It is crucial that we find effective, long-term treatments,” he added.

Professor Clive Ballard, Director of Research at the UK’s Alzheimer’s Society, said in a statement that 1 in 3 people over the age of 65 will develop dementia, and while finding a cure the priority, it is also important to fund studies like this, so we can develop treatments that help people live well with the condition.

“This is probably the most exciting drug we know about that is currently in the late stages of research. We now know it is safe but the real test will be whether these initial promising results can be replicated in larger groups,” said Ballard.

He suggests if the phase 3 trial is successful, and the drug can be made cost-effective, then we could see the drug on the shelves in the next 10 years.

The reason IVIG appears to have an effect against Alzheimer’s is not clear: but many scientists believe it could be that the antibodies bind to beta amyloid, clear it from the brain, and block its toxic effects on brain cells. Beta amyloid is the main component of amyloid plaques, the deposits found in the brains of patients with Alzheimer’s disease.

Written by Catharine Paddock PhD