Biogen's Alzheimer's drug impresses in early study with Phase III on the way

Biogen Idec's ($BIIB) heavily scrutinized Alzheimer's disease program came through with some positive early results, improving cognition and blasting away brain plaques in a small study many see as a validation of the company's ambitions in the field.

The treatment, BIIB037, is an antibody targeting beta amyloid proteins, buildups in the brain widely believed to contribute to Alzheimer's neurodegenerative effects. In a Phase Ib study involving 166 patients with mild forms of the disease, three out of four dosage levels of BIIB037 led to statistically significant reductions in beta amyloid compared to placebo after 26 weeks, and, for the two doses with enough data to measure, that effect was even greater at week 54.

On the cognitive side, patients taking placebo experienced an average 3.14 decline as measured by the Mini Mental State Examination, a standardized test of impairment, while those on the highest dose of BIIB037 declined by 0.58--a statistically significant difference. And on the Clinical Dementia Rating scale, patients getting the high dose of Biogen's antibody worsened by 0.59 points compared to 2.04 on placebo, also statistically significant.

But safety issues could restrict that level of dosing for some patients, Biogen noted. The most common side effect of BIIB037 was ARIA, or amyloid-related imaging abnormalities, which results in dangerous brain swelling. Incidences of ARIA were dose-dependent, the company said, and they were more common in patients who carry the ApoE4 gene, which is believed to predispose patients to Alzheimer's risks. Patients in that population were more likely to discontinue treatment due to ARIA, Biogen said.

Looking at the totality of the Phase Ib for its antibody, now rechristened aducanumab, Biogen is calling it a victory, and the company is already at work designing a Phase III study with plans to kick off enrollment this year.

Biogen Idec CMO Dr. Alfred Sandrock

"This is the first time an investigational drug for Alzheimer's disease has demonstrated a statistically significant reduction on amyloid plaque as well as a statistically significant slowing of clinical impairment in patients with prodromal or mild disease," Chief Medical Officer Dr. Alfred Sandrock said in a statement.

The Big Biotech's shares rose about 5% on the data Friday morning, reaching an all-time high.

Biogen hopes its antibody can succeed where so many once-promising programs have failed. Many Alzheimer's treatments--including Eli Lilly's ($LLY) solanezumab and Pfizer ($PFE) and Johnson & Johnson's ($JNJ) bapineuzumab--have demonstrated great potential in early trials only to fail miserably in Phase III, contributing to a daunting 99.6% clinical trial failure rate for such drugs, according to Cleveland Clinic's Dr. Jeffrey Cummings.

Scientists and investors who believe things will be different this time are buying into two major hypotheses: that Biogen's antibody is simply better than those that came before, and that the company's strategy of targeting mild Alzheimer's patients is the key to maintaining an efficacy signal through late-stage trials. Whether either is correct will remain unknown until Phase III data is ready in a few years.

Aducanumab is one facet of Biogen's all-hands approach to Alzheimer's. Alongside partner Eisai, the company is working on a treatment that targets beta secretase, which is key to the production of amyloid, and one that homes in on the tau protein, also found in Alzheimer's sufferers. Per a deal signed in March, Eisai has the option of jointly developing BIIB037 under undisclosed terms.

- read the results

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