Baxter International’s Phase 3 clinical trial of immunoglobulin (IG) did not meet its co-primary endpoints of reducing cognitive decline and preserving functional abilities in patients with mild to moderate Alzheimer’s disease.

The Gammaglobulin Alzheimer’s Partnership (GAP) study was a randomized, double-blind, placebo-controlled, multi-center trial conducted to study the safety and effectiveness of Baxter’s IG for the treatment of signs and symptoms associated with Alzheimer’s disease. 

Patients with mild-moderate Alzheimer’s disease (N=390) were randomized to receive Baxter’s IG treatment at either the 200mg/kg or 400mg/kg dose every two weeks for 18 months, or placebo. All patients were required to continue taking their approved treatment medications to manage Alzheimer’s disease symptoms.

After 18 months of treatment, patients taking either the 200mg/kg or 400mg/kg dose did not demonstrate a statistically significant difference in the rate of cognitive decline compared to placebo (mean 7.4 in the 400 mg/kg group, 8.9 in the 200 mg/kg group, and 8.4 in the placebo group). The results also did not show a statistically significant change in functional ability compared to placebo (mean -11.4 in the 400 mg/kg group, -12.4 in the 200 mg/kg group, and -11.4 in the placebo group).

The study was not powered to demonstrate statistical significance among sub-groups. In the pre-specified sub-group analysis, the 400mg/kg treatment arm showed a positive, numerical difference in change from baseline vs. placebo in cognition. In moderate patients and carriers of the ApoE4 genetic marker, differences ranged between 16% and 29%.

Baxter has suspended current studies of IG in mild-moderate Alzheimer’s disease.

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