An immunoglobulin-based therapy in development at Baxter as a treatment for Alzheimer’s disease has failed to show any benefit in a phase III trial.
The immunoglobulin product – already sold as Gammagard/Kiovig for the treatment of primary immunodeficiency disorders – was no better than placebo at improving cognitive and functional measures in the Gammaglobulin Alzheimer’s Partnership (GAP) study.
Baxter said it would discontinue its current studies of Gammagard in Alzheimer’s but was not writing off the approach entirely, as a subgroup analysis in the 390-patient trial showed that at the highest dose tested (400mg/kg) the immunoglobulin showed a trend towards improvement in some patients.
Specifically, the drug seemed to be having an impact on symptoms in patients with moderate disease who were also carriers of a genetic marker – called ApoE4 – that increases the risk of Alzheimer’s. Previous studies have suggested ApoE4 is involved in a cascade of events that disrupt the brain’s vascular system.
The announcement is reminiscent of Lilly’s decision to stick with its anti-amyloid therapy solanezumab, despite failed late-stage studies, and test it in a slightly different patient population. The stories diverge, however, in that while Lilly is now testing its drug in very early-stage patients, Gammagard seemed to have an impact only in more advanced disease.
Immunoglobulin therapy has been proposed as a possible way to tackle both amyloid plaques and tau tangles – two of the hallmark pathologies seen in the Alzheimer’s-affected brain – so if nothing else the data from the trial could help boost understanding of the mechanisms underlying the disease.
“We’ll re-evaluate our clinical approach once we’ve analysed the full data set,” said Baxter chief executive Robert Parkinson on a conference call to discuss the GAP results and other matters yesterday.
“There were some interesting findings that we are in the process of evaluating, and we hope to continue to focus on development in this area,” he added.