* Currently no approved medicines to slow Alzheimer's
* Crenezumab fails to meet main goals in mid-stage study
* Signs of benefit at higher dose in milder patients
By Caroline Copley
ZURICH, July 16 Roche said its experimental Alzheimer's drug failed to meet its main goals in a mid-stage study, a result likely to bolster the belief that drugs need to be given in earlier stages of the disease to slow patients' decline.
The Swiss drugmaker's treatment known as crenezumab was tested in patients with mild-to-moderate forms of Alzheimer's, a fatal, brain-wasting disease that gradually robs patients of their ability to think and care for themselves.
Results of a Phase II study involving 431 patients found crenezumab failed to significantly slow cognitive and functional decline compared to placebo, missing two main goals, Roche said in a statement on Wednesday.
But an exploratory analysis of patients with a milder form of the disease who received a higher dose of crenezumab via an intravenous infusion showed a statistically significant reduction in cognitive decline, Roche said.
Carole Ho, director of Early Clinical Development at Roche's biotech unit Genentech told Reuters in an interview said she was encouraged by the data, even though it missed its main goals, since it demonstrated that treating the disease earlier could increase the benefit.
Ho said Roche would decide on any future plans for additional clinical studies following an analysis of the data in conjunction with health authorities.
Analysts had expected crenezumab to fail its main goals, after a similar treatment from Pfizer Inc and Johnson & Johnson called bapineuzumab and solanezumab, a drug from Eli Lilly and Co failed in late-stage trials.
Lilly has since started a new clinical trial focusing only on patients with mild signs of the disease.
Some trials are already underway testing people who have not yet shown any symptoms of Alzheimer's to try and gauge whether early intervention can prevent or slow the disease.
Crenezumab, which was licensed from Swiss biotech company AC Immune in 2006, works by blocking the toxic protein beta-amyloid that forms plaques in the brain believed to signal the onset of the disease.
Roche said a smaller Phase II biomarker study also showed an effect of slowing cognitive decline in milder patients. Details of this study will be presented at the Clinical Trials in Alzheimer's Disease meeting in November.
Jeffrey Cummings, director of the Cleveland Clinic Lou Ruvo Center for Brain Health who presented the crenezumab data at the Alzheimer's Association International Conference in Copenhagen, said he was encouraged by the consistent benefit seen in the most mild patients.
"It has been very difficult to have any convincing evidence of a treatment effect in Alzheimer's Disease," Cummings said. "When you see this kind of consistency across two trials then you would definitely want to advance a drug in a trial that focuses specifically on very mildly affected patients."
The drug was well tolerated with only one case of vasogenic edema, a brain swelling side effect seen in similar drugs, allowing crenezumab to be administered at higher doses, Roche said, though patients taking the medicine did have a higher incidence of pneumonia than those on placebo.
At lower doses when crenezumab was administered through an injection beneath the skin no significant benefit was seen even in milder patients, the results revealed.
Alzheimer's - the most common form of dementia - already afflicts 44 million people worldwide and this figure is set to triple by 2050, according to campaign group Alzheimer's Disease International.
Unlike heart disease and cancer, which have seen major strides in drug development, no new therapies have been approved to treat Alzheimer's in a decade, according to a recent study from researchers at the Cleveland Clinic. Current drugs only treat symptoms despite years of research.
A startling 99.6 percent of clinical trials in Alzheimer's failed between 2002 and 2012, the Cleveland Clinic study found.
Crenezumab has been picked for a U.S. government-backed trial in a group of Colombians with a genetic mutation that causes them to develop Alzheimer's early. Results of that trial are due in 2020.
A second Alzheimer's drug from Roche, known as gantenerumab, is also being investigated in a late-stage trial with patients who are yet to develop any signs of the disease. (Reporting by Caroline Copley; Editing by Elaine Hardcastle)