Lars Lannfelt, MD, Uppsala University Hospital, Uppsala, Sweden; Craig Ritchie, MD, Imperial College, London, United Kingdom; and colleagues did a randomised trial to test the safety and efficacy of PBT2 and its effect on the biomarkers of Alzheimer's disease.

The trial included 78 patients aged 55 years or older who were randomised to receive PBT2 50 mg (n = 20 patients), PBT2 250 mg (n = 29), or placebo (n = 29). All patients had early Alzheimer's disease.

Cognition testing included several standard tests for Alzheimer's patients. Patients taking PTB2 250 mg showed improvement in 2 of the executive function tests compared with placebo.

In the first test -- Trail Marking Part B -- patients on PBT2 250 mg were able to complete the task by an average of 48 seconds faster than they had at the beginning of the trial. The placebo group was an average of 5 seconds slower.

In the Category Fluency Test, which looks at a person's ability to come up with as many relevant words as possible in relation to a specified category, those in the 250-mg group were able to produce an average of 2.8 more words than at the beginning of the trial compared with a decrease of 0.3 words in the placebo group.

Levels of amyloid-beta in the spinal fluid of the group on PBT2 250 mg were reduced by 13% compared with placebo at the end of the 12-week trial.

There were no significant differences in tests assessing memory between PBT2 and placebo patients. However, the researchers say that this could be because memory functions deteriorate more slowly than executive ones during early-stage Alzheimer's disease, making changes harder to detect in such a short study.

In terms of safety, no serious adverse events were reported by patients on PBT2, and proportions of patients reporting other adverse events were similar in the 3 groups.

"The safety profile is favourable for ongoing development of PBT2," the authors wrote. "Future trials that are larger and longer will establish if the effects of PBT2 on biomarkers and cognition that are reported here translate into clinical effectiveness."

In an accompanying comment, Norman R. Relkin, MD, Memory Disorders Program, Weill Cornell Medical College, New York, New York, said, "To go forward as an Alzheimer's disease treatment, PBT2 must still surmount the high hurdle of additional safety and efficacy testing in large-scale clinical trials."

SOURCE: The Lancet Neurology

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