Dr. Eric M. Reiman, psychiatry professor at the University of Arizona College of Medicine in Phoenix

A University of Arizona physician is helping to lead a clinical trial to test drugs that could delay or prevent Alzheimer’s disease in certain people.

The multimillion-dollar medical trial is part of a partnership between the Phoenix-based Banner Alzheimer’s Institute and the Swiss drug company Novartis.

The trial will test whether two drugs can prevent or delay the emergence of Alzheimer’s in people who are at a particularly high risk for developing the disease at older ages.

“We think it’s a major step in the effort to try to find treatment to prevent the clinical onset of Alzheimer’s disease,” said Dr. Eric M. Reiman, executive director of the Banner Alzheimer’s Institute, a professor of psychiatry at the UA College of Medicine in Phoenix and director of the Arizona Alzheimer’s Consortium.

Many researchers have suggested amyloid protein plays a critical role in the development of Alzheimer’s, and the two drug therapies attack amyloid in different ways.

“We’re not sure which forms of amyloid are the critical ones in the development of Alzheimer’s. It provides a diversified approach,” said Reiman, who is a study director for the Banner Alzheimer’s Institute.

The study will target cognitively healthy older adults who inherited two copies of the apolipoprotein E (APOE4) gene — one from each parent. APOE4 is the major genetic risk factor for developing Alzheimer’s at older ages. Individuals with two copies have a particularly high risk.

About 2 percent of the world’s population carries two copies of the gene. A far larger number — one in four — carry one copy of the APOE4 gene, Reiman said.

At least one copy of the APOE4 gene is found in more than half of the people with Alzheimer’s dementia in older age, he noted.

Participants will receive either active immunotherapy or an oral BACE inhibitor medication or a placebo.

The active immunotherapy is aimed at triggering the body’s immune system to produce antibodies that attack different forms of the amyloid protein.

The BACE inhibitor is a molecule that inhibits the activity of an enzyme called BACE. By inhibiting BACE, the production of many forms of amyloid are also inhibited, Reiman explained.

The trial is subject to regulatory authority approval and will begin in 2015 at approximately 60 sites in Europe and North America.

The study received a $33.2 million grant commitment from the National Institutes of Health, part of the U.S. Department of Health and Human Services, awarded in 2013. Novartis is providing an undisclosed amount of financial support.

“This approach shifts the research paradigm from trying to reverse disease damage to attacking and preventing its cause, years before symptoms could surface,” said another Banner Alzheimer’s Institute study director, Dr. Pierre N. Tariot, in a prepared statement.

Participants will be recruited via multiple venues, including the Alzheimer’s Prevention Registry website created by Banner Alzheimer’s Institute in 2012. The registry (endALZnow.org) has more than 37,000 potential volunteers and is aiming to recruit more than 250,000.

Volunteers who are selected will receive genetic counseling, as will others who are not chosen but who seek more information on their vulnerability.

Without the discovery of successful prevention therapies, the number of U.S. Alzheimer’s cases is projected to nearly triple by 2050, Banner officials say.

Contact reporter Stephanie Innes at sinnes@tucson.com or 573-4134.