Marking a milestone in its 15-year history, the Buck Institute for Research on Aging announced the start of its first human clinical trial of a drug that may provide treatment for an early indicator of Alzheimer’s disease, the deadly brain disorder that afflicts more than 5 million Americans.

The trial in Australia, involving 36 patients with amnestic mild cognitive impairment, or a MCI, is testing the safety and preliminary efficacy of a drug code-named F03.

“We are crossing our fingers and hoping” for favorable results, said Stelios Tzannis, the Buck Institute’s director of clinical sciences. “This is a big bet, of course.”

If the results, expected by the end of next summer, are successful, the next step would be a trial with more patients in Australia and the United States, he said. Ultimately, F03 could be approved by the Food and Drug Administration for use in treating aMCI and Alzheimer’s in the U.S. in eight to 10 years.

Scientists do not fully understand the cause of Alzheimer’s, nor is there a treatment for the sixth-leading cause of death in the nation, primarily among people age 65 and over.

Tzannis said it is “too early to talk about a cure,” but F03 has shown “the potential of reversing memory loss.”

The drug was identified as a potential Alzheimer’s therapy by research in the Buck laboratory headed by Dale Bredesen, a neurobiologist who was the Buck Institute’s founding president and CEO in 1998. F03 “addresses a key process in the brain that is distorted early on in the development of Alzheimer’s disease,” the institute said in a press release.

An international scientific scramble is on to stem Alzheimer’s, which costs more than $200 billion and claims 83,500 lives a year in the United States, including nearly 250 in Sonoma County. The death rate for Alzheimer’s disease in Sonoma County is 51 per 100,000 population, compared with the statewide rate of 29 per 100,000 population, according to the California Department of Public Health.

Tzannis said that F03, which has been used in Australia and 48 other countries for a different reason, is a “pretty safe compound.” He declined to give any details about the drug because its identity is a secret.

“This is a drug we know a lot about,” he said.

In lab tests on mice with significant memory loss, F03 doses enabled “full recovery of their memory,” Tzannis said.

Those results are encouraging, he said, but he noted that test outcomes on mice are not always replicated in human trials.

The Buck Institute, known for its landmark white marble-clad building on a hillside west of Highway 101 in Novato, is an independent nonprofit organization dedicated to extending the human lifespan. It will continue to focus on research, Tzannis said, while the F03 trial marks a crossover into pharmaceutical development.

Buck hopes to make money from drugs such as F03, he said, citing the need for financial support of research.

The institute would likely partner with a large pharmaceutical firm to cover the cost of future clinical trials and drug development.