Biogen and Eisai on Thursday said an independent data monitoring committee determined that the experimental anti-amyloid beta protofibril antibody BAN2401 "did not meet the criteria for success" based on an analysis at 12 months as the primary endpoint in a mid-stage trial. "By using Bayesian statistics in this uniquely-designed trial we had hoped that it would enable us to demonstrate clinical success faster than more traditional study designs," commented Lynn Kramer, chief clinical and medical officer for Eisai's neurology business.
The companies "now await the final study analysis which will be conducted after 18 months of treatment, which represents an amount of treatment time that is considered as appropriate for assessing efficacy in disease modifying agents for Alzheimer's disease," she added. Results from the final analysis are expected in the second half of 2018.
Study 201 involves 856 patients with prodromal or mild Alzheimer's disease, and positive biomarkers for brain amyloid pathology. Patients were randomised to placebo or one of five treatment arms, consisting of three dose levels of BAN2401 administered bi-weekly and two dose levels given on a monthly basis. According to the companies, the trial "allows for automatic changes to the design during the study, including adaptively changing the subject allocation ratio to treatment arms with higher probabilities based on the results of interim analyses in order to more efficiently identify the effectiveness and optimal dose regimen of BAN2401."
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Biogen and Eisai noted that none of the 16 interim analyses already conducted had found potential for futility or the need to stop for safety reasons. The drugmakers explained that efficacy of the five BAN2401 dose groups was evaluated using Eisai's in-house developed Alzheimer's disease Composite Score (ADCOMS). The Bayesian analysis at 12 months indicated that "success was judged as an 80-percent or higher probability of achieving" at least a 25-percent reduction in the rate of decline of ADCOMS versus placebo, the companies noted.
Eisai licenced exclusive global rights to BAN2401 from BioArctic in 2007, and has been jointly developing the drug with Biogen under the terms of a 2014 agreement focused on treatments for Alzheimer's disease. Earlier this year, Eisai exercised its option to jointly develop and promote Biogen's investigational anti-amyloid beta antibody aducanumab. Mizuho analyst Salim Syed suggested the Study 201 update, which sent Biogen's shares down as much as 4.3 percent, should be viewed separately from upcoming Phase III data for aducanumab, saying "BAN2401 and aducanumab are not the same antibody."
Meanwhile, Evercore ISI analyst Umer Raffat indicated that Study 201 could still succeed at 18 months, adding that if efficacy scores are 25 percent or more than those of a placebo, and the drug shows very limited abnormal neuroimaging differences in patients, BAN2401 will likely advance to Phase III testing. However, analysts at Barclays said the interim results for BAN2401 could renew debate about whether amyloid is a major factor in Alzheimer's disease.
For related analysis, see ViewPoints: Biogen, Eisai double down on aducanumab.
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