Shares in Baxter took a downturn yesterday after it emerged its immunodeficiency drug Gammagard failed to offer any benefit to patients with Alzheimer's disease (AD), despite having shown great promise in earlier trials.

A Phase III study involving 390 patients with mild-to-moderate forms of AD failed to hit co-primary endpoints of reducing cognitive decline and preserving functional abilities.

Top-line analysis of data from the trial indicate that, after 18 months of treatment, patients taking Gammagard (immunoglobulin [human]) did not show a statistically significant difference in the rate of cognitive decline compared to placebo, nor was there a statistically significant change in functional ability.

There may, however, be a small glimmer of hope for the drug in AD, as there was a numerical difference in cognition seen in both patients with moderate disease and those carrying the genetic marker ApoE4 in the high dose group versus placebo, although further assessment will be necessary to determine this potential benefit.

"The study missed its primary endpoints, however we remain interested by the pre-specified sub-group analyses", said Ludwig Hantson, president of Baxter's BioScience business.

However, based on the results, Baxter said it will reconsider its current approach for Alzheimer's, and all studies of immunoglobulin in mild-to-moderate AD will be discontinued. 

The news will be particularly disappointing given that the drug's performance in mid-stage trials had been very encouraging.

In 2010, Baxter reported results from a Phase II trial showing that, after 18 months of treatment, patients receiving Gammagard exhibited less cognitive decline than those given a placebo, dropping only six points on the AD Assessment Scale-Cognitive Subscale score compared to 15, respectively.

Hopes dashed

In fact, Baxter said at the time that the study was the first in AD in which all three measures - cognitive, functional and neuroimaging - had positive data and were statistically significant.

But unfortunately, the observations seen in earlier studies did not translate into a positive outcome in Phase III trial, said Norman Relkin, a neurologist from the Weill Cornell Medical College and GAP Study Leader.

The news will also come as blow to AD patients, as it follows a spate of high-profile late-stage failures including Johnson & Johnson and Pfizer's intravenous bapineuzumab and Eli Lilly's solanezumab.

Additional analyses from the study will be presented at the Alzheimer's Association International Conference later this year, the firm said.