October 31, 2019

Impact: High

In March this year, the aducanumab phase 3 Alzheimer’s disease trials were stopped based on futility, meaning that it was statistically almost impossible for the study to meet its endpoint. The operative word was apparently “almost.”

Full analysis of the phase 3 results now shows that the high dose arm of aducanumab, an anti-amyloid antibody, did indeed meet its primary and secondary endpoints, demonstrating significantly slower cognitive decline than the placebo group by CDR-sum of boxes (23% difference at 1.5 years, p=0.01 vs. placebo in the EMERGE trial). Aducanumab was also associated with reduction in brain amyloid. Safety was “consistent with earlier studies.”

Based on these results, Biogen and Eisai will file for aducanumab approval in early 2020, and are also restarting the extension studies of aducanumab. Aducanumab could be marketed as the first approved disease modifying Alzheimer’s disease drug by the end of 2020.

Biogen stock added approximately $20 billion in value as a result of this news.

Full data are expected at the CTAD meeting in December.

inThought Analysis

Biogen and Eisai released a significant amount of information about the primary and secondary endpoints as well as safety in their press release, but the full details of the EMERGE and ENGAGE trials will be watershed events at the CTAD meeting in San Diego in early December. Neurologists will be keen to understand if the benefits of aducanumab were seen disproportionately in earlier stage Alzheimer’s patients, in specific subgroups such as those with certain ApoE genotypes, and whether the efficacy correlates with declined amyloid burden and/or ARIA events.

Source: Biogen and Eisai Press Release