Despite the failure to meet half its goals in the trial, Voyager's Christopher Gregory, vice president of the company based in Raleigh, N.C., said researchers would continue to pursue a pivotal set of twin phase 3 studies in hopes of improving results so that the drug can win Food and Drug Administration approval.
The study that pooled data from two trials was reported at the 10th International conference on Alzheimer's Disease and Related Disorders in Madrid, Spain. Gregory explained that the trial was designed to show that leuprolide acetate - in Voyager's proprietary formulation - would both halt the decline in cognition among patients with Alzheimer's disease and that the patients' doctors would be able to see clear cut differences between the patients taking leuprolide and those that were not on the drug.
In fact, on the Alzheimer's Disease Cooperative Study-Global Impression of Change, doctors did seen significant differences. "Doctors rated 50.9 percent of the patients on leuprolide as unchanged or improved," Gregory told United Press International, "whereas only 34.5 percent of the patients not taking leuprolide showed no change or improvement."
That difference reached statistical significance, he said. But the other side of the coin, a second primary goal of the study was not met.
In the Alzheimer's Disease Assessment Scale - cognitive subscale, patients on leuprolide slipped about 2 points iover the year long study compared with a 3 to 5-point fall among those not taking the drug. That difference was not considered significant.
In Alzheimer's disease patients slowly decline, losing memory, then ability to care for themselves and eventually requiring institutionalization and then death in a period that can range from 3 to 15 years after diagnosis.
Pharmaceuticals in the past decade have been able to slow that rate of descent into the loss of personal humanity, but researchers continue to hunt for new treatments.
Gregory told UPI that leuprolide - a treatment widely used for patients with advanced, metastatic prostate cancer - came to their attention almost by accident. A woman told her doctor that her husband, who was on leuprolide, appeared to no longer be affected by his Alzheimer's.
Leuprolide attacks certain hormones in its attempt to prevent prostate cancer from spreading, and similar hormones have been found to be a key driving mechanism of Alzheimer's. By giving patients leuprolide, the hormones in the brain are destroyed - hopefully, Gregory and his team think, slowing Alzheimer's.
"I find this phase 2 data to be very promising," said Howard Fillit, the founding executive director of the Institute for the Study of Aging, who acted as moderator at a press briefing at which Gregory's study was discussed. "The fact that the clinical impression of doctors that the patients had improved is impressive and meaningful," Fillit told UPI.
Fillit noted that leuprolide works differently that other drugs used to treat Alzheimer's disease - namely so-called cholinesterase inhibitors. In the Voyager study all the patients were taking cholinesterase inhibitors. Leuprolide was added to the drug regime of half the 227 patients in the studies, while the other half of the patients received sham medication known as placebo.